Illingworth's The Development of the Infant and Young Child: Normal and Abnormal PDF

 Illingworth’s The Development of the Infant and Young Child Normal and Abnormal Prelims.indd i 09/08/12 3:56 PM “This page intentionally left blank"  Illingworth’s The Development of the I...

 Illingworth’s The Development of the Infant and Young Child Normal and Abnormal Prelims.indd i 09/08/12 3:56 PM “This page intentionally left blank"  Illingworth’s The Development of the Infant and Young Child Normal and Abnormal Tenth Edition Author Ronald S Illingworth MD FRCP DPH DCH Hon MD Sheffield, Hon DSc Baghdad, Hon DSc Leeds Emeritus Professor of Child Health, The University of Sheffield; Formerly Paediatrician, The Children’s Hospital, Sheffield and the Jessop Hospital for Women, Sheffield, South Yorkshire, UK Editors MKC Nair MD PhD M Med Science (Newcastle) Professor of Paediatrics Child Development Centre, Thiruvananthapuram, Kerala, India Paul Swamidhas Sudhakar Russell MD Professor of Psychiatry Christian Medical College, Vellore, Tamil Nadu, India ELSEVIER A division of Reed Elsevier India Private Limited Prelims.indd iii 09/08/12 3:56 PM  Illingworth’s The Development of the Infant and Young Child: Normal and Abnormal, 10/e Nair and Russell ELSEVIER A division of Reed Elsevier India Private Limited Mosby, Saunders, Churchill Livingstone, Butterworth-Heinemann and Hanley & Belfus are the Health Science imprints of Elsevier. © 2012 Elsevier Ninth Edition 1987 Tenth Edition 2012 All rights are reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise without the prior permission of the publisher. This edition of The Development of the Infant and Young Child: Normal and Abnormal, by Ronald S Illingworth MD FRCP DPH DCH, MKC Nair MD PhD M Med Science (Newcastle) and Paul Swamidhas Sudhakar Russell MD is published by an arrangement with Illingworth Estate. Original ISBN: 0-443-03840-6 ISBN: 978-81-312-3020-6 Medical knowledge is constantly changing. As new information becomes available, changes in treatment, procedures, equipment and the use of drugs become necessary. The author, editors, contributors and the publisher have, as far as it is possible, taken care to ensure that the information given in this text is accurate and up-to-date. However, readers are strongly advised to confirm that the information, especially with regard to drug dose/usage, complies with current legislation and standards of practice. Please consult full prescribing information before issuing prescriptions for any product mentioned in this publication. Although all advertising material is expected to conform to ethical (medical) standards, inclu- sion in this publication does not constitute a guarantee or endorsement of the quality or value of such product or of the claims made of it by its manufacturer. Published by Elsevier, a division of Reed Elsevier India Private Limited. Registered Office: 305, Rohit House, 3 Tolstoy Marg, New Delhi-110 001. Corporate Office: 14th Floor, Building No. 10B, DLF Cyber City, Phase II, Gurgaon–122 002, Haryana, India. Sr. Commissioning Editor: Shukti Mukherjee Bhattacharya Managing Editor (Development): Shabina Nasim Development Editor: Shravan Kumar Copy Editors: Shrayosee Dutta, Richa Srivastava Manager Publishing Operations: Sunil Kumar Manager Production: NC Pant Production Executive: Ravinder Sharma Typeset by Chitra Computers, Delhi Printed and bound at EIH Unit Ltd. Press, Manesar. Prelims.indd iv 09/08/12 3:56 PM  Biography Ronald Stanley Illingworth was born on 7 October 1909 in Harrogate, North Yorkshire, England. He was educated at schools in Harrogate and Bradford and went with a scholarship in classics to read medicine at Leeds University. After graduating MB ChB in 1934 he held posts in hospital medicine and general practice and obtained the MD and MRCP in 1937, and the DPH and DCH in 1938. He worked at the Hospital for Sick Children at Great Ormond Street in London, and then as a Nuffield research student in Oxford. Illingworth joined the Royal Army Medical Corps in 1941, and by the end of World War II he was a lieutenant-colonel and in charge of a medical division in the Middle East. In 1946 he went to the USA on a Rockefeller research fellowship and worked at Yale with Arnold Gesell and Catherine Amatruda, who inspired his interest in child development. In 1947 he was appointed to the foundation chair of child health in the University of Sheffield. Over the next twenty-eight years he made Sheffield Children’s Hospital and his department of child health a port of call for aspirant academics and future consultants from home and abroad. Illingworth was an astute clinician and a meticulous clinical researcher. He became the foremost clinical expert on developmental paediatrics. His prodigious output of papers and books included over 650 publications. He was undoubtedly the most widely read paediatrician of his time. His best known books are The Normal Child (1953, ten editions), The Development of the Infant and Young Child (1960, nine editions), and Common Symptoms of Disease in Children (1967, nine editions). All three were translated into many languages. Illingworth had an eminently readable style of writing, being economical with words and precise in their use. His writings were a model of clarity and very popular with students and postgraduate scholars. His passion for photography is evident from his photographs, for which he received over seventy prizes. He was a Fellow of the Royal Photographic Society. His superb use of illustrated material, combined with his effortless and lucid style of delivery, made him a much sought-after lecturer throughout the world. He served on major committees of the Medical Research Council and Department of Health, and was the paediatric adviser to the Parliamentary Prelims.indd v 09/08/12 3:56 PM  vi Biography Commissioner (Ombudsman). He had a special interest in medico-legal matters and was on the Council of the Medical Defence Union for 26 years. After he retired as Professor of Child Health in 1975 he started anew as a clinical medical officer running a well baby clinic, and he published a further two hundred medical papers and new or revised editions of several books. In 1947 he married Cynthia Redhead, a paediatrician. Together they wrote two books: Babies and Young Children (seven editions) and Lessons from Childhood. They had one son and two daughters, who all became doctors and married doctors, and six grandchildren. Illingworth died on 4 June 1990 while on holiday in Norway, amongst the mountains and lakes where he was so fond of walking and taking photographs. —This is based on the biography written by Prof. Frank Harris (who worked with Prof. Ronald Illingworth for several years) published in Nicholls CS, ed., The Dictionary of National Biography: 1986–1990. Oxford University Press; 1996:220–1. Books by Professor Ronald S Illingworth: The Normal Child—Ten editions. Translated into Spanish, Greek, Japanese, Italian, Farsi, French and German. The Development of the Infant and Young Child: Normal and Abnormal—Nine editions (before this editon). Translated into Japanese, French, Spanish, Italian and Polish. Common Symptoms of Disease in Childhood—Nine editions. Translated into Greek, Italian, Spanish, German, Indonesian and Portuguese. Indian edition 1989. Babies and Young Children: Feeding, Management and Care (with Dr Cynthia Mary Illingworth)—Seven editions. Translated into Polish. Lessons from Childhood: Some Aspects of the Early Life of Unusual Men and Women (with Dr Cynthia Mary Illingworth)—1966. Translated into Japanese. An Introduction to Developmental Assessment in the First Year—1962 The Normal School Child—1964 Treatment of the Child at Home: A Guide for Family Doctors—1971. Translated into Greek. Basic Developmental Screening—Five editions. Translated into Greek, Japanese, Italian and Spanish. The Child at School: A Paediatrician’s Manual for Teachers—1974. Translated into Italian. Infections and Immunisations of Your Child—1981. Translated into Spanish. Your Child’s Development in the First Five Years—1981. Translated into Spanish and Indonesian. Prelims.indd vi 09/08/12 3:56 PM  Preface to the Tenth Edition When we were first asked to adapt and edit the Tenth Edition of Professor Illingworth’s The Development of the Infant and Young Child: Normal and Abnormal, we felt what almost seemed like a compulsion to see this well renowned book updated with current evidence on child development. After a year of finding and fixing new scientific support, while revising this classical book, we sure can say it was our privilege to have attempted it. It has been over two decades since the last edition of the book was published. The discipline of child development has changed and grown at a rapid pace during this period. Our understanding about the epidemiology, pathogenesis and treatment of many conditions associated with child development has resulted in better outcomes as has been documented with low-birth weight babies. Advances in medical technology has resulted in better diagnostic methods; progress in developmental and cognitive psychology has resulted in the delineation of the behavioural phenotypes of many disorders with intellectual disability as a component as well as clinical measures with better diagnostic accuracy and effective early interventions. The social changes occurring alongside have encouraged international adoption and adoption by same sex parents, altering the traditional family structure and processes. All these developments have been included in this edition of the book along with the use of politically appropriate terminologies. For those used to the previous editions, the layout of this book will look familiar. This edition of the book focuses on the same topics in a recognisable order of chapters as the audience continue to be paediatrician, psychologists, teacher, educated parent, or anyone else interested in better understanding the how’s and why’s of the variation in a child’s development that does not amount to disease. In this edition, we have included many new references to keep with the accumulating evidence to support or query the original observations and yet, we have endeavoured to retain the quotes of Professor Illingworth and therefore many of the observations are in first person singular. A great deal of original clinical case material is presented throughout the book as well. Moreover, we have continued to maintain this edition of the book too as a practical book on the method of developmental diagnosis and not a textbook on child development as Professor Illingworth had always wanted. Finally, no book is ever the product of just editors. Illingworth’s The Development of the Infant and Young Child: Normal and Abnormal is the result of the hard work put forth by several people and we gratefully acknowledge their work. We Prelims.indd vii 09/08/12 3:56 PM  viii Preface to the Tenth Edition appreciate the assistance provided by Leena Sumaraj, Preethi Menon, Raman Krishnan and Sushila Russell at different stages of readapting this book. To you audience—thank you for reading this book and welcome to the exciting, fascinating and ever-changing world of child development. Thiruvananthapuram MKC Nair Vellore Paul Swamidhas Sudhakar Russell 2012 Prelims.indd viii 09/08/12 3:56 PM  Preface to the Ninth Edition In preparing this new edition I have repeatedly read every word of the previous one. I have made a more rational arrangement of chapters. Many sections have been completely rewritten, including the value and importance of developmental assessment, the different approaches of psychologist and clinician to the method of assessment, the essential principles of developmental diagnosis, the range of normality, the fallacies in norms of development, prenatal factors, the prognosis of very low birth weight infants, the prediction of mental superiority, and the problems of learning disorders and brain damage. Summaries have been added to several chapters. Great care has been taken to make the index comprehensive. I have throughout tried to include useful and helpful references, deleting some old ones, and adding over 130 new ones, though trying to keep the number down to a minimum for reasons of space. Once more reviewers have criticised me for not including the pathology of disease, physical development, laboratory investigation and treatment of disease. But it was never my intention to include those: it would involve very considerable lengthening of the book, making it run into two or three volumes. The whole purpose of this book has always been to try to help in the understanding and basis of normal development, the reasons for variations, the methods of establishing developmental diagnosis, and the avoidance of pitfalls in diagnosis and prediction. This has been based on many years of experience since I was taught the rudiments by Arnold Gesell and Catherine Amatruda, who enabled me to continue to learn in subsequent decades. I have throughout tried to make this a practical book on the method of developmental diagnosis. Sheffield, 1987 R.S.I. Prelims.indd ix 09/08/12 3:56 PM “This page intentionally left blank"  Preface to the First Edition A thorough knowledge and understanding of the normal development of the infant and young child is just as fundamental to anyone concerned with the care of children, especially paediatrician, as is anatomy to the surgeon. Family doctors, paediatricians and others must know the normal, and the variations from the normal, before they attempt to diagnose the abnormal. I doubt whether a paediatrician will complete any out-patient clinic without having had to make at least one developmental assessment. Without such an assessment he is unable to make a proper diagnosis, to arrange proper treatment, and to help the parents or family doctor or school medical officer as much as he should. The doctor inevitably has to assess the development of every baby which he sees in a well baby clinic, for otherwise he is not doing his job properly; he could not hope to diagnose the abnormal, to detect the early signs of cerebral palsy or of mental subnormality, or a hearing or visual defect, of subluxation of the hip, or of hydrocephalus, unless he were first conversant with the normal and then looked for the variations from the normal. In the hospital ward one does not carry out a developmental examination on an ill child with bronchopneumonia, and in a private house one does not assess the development of every young child with asthma; but in both places there are innumerable circumstances in which a developmental examination is essential, and without it the examination is seriously incomplete. It is because I regard developmental assessment as an essential part of everyday practice that I wrote this book, in order to describe just what can be learnt about a child’s development with a minimum of equipment in an ordinary mixed clinic, and not in a special room, at a special time, or with special complicated equipment. Everyone dealing with children needs this knowledge. It is not just the province of an expert who does nothing else. Because I am convinced that the best assessment must be based on a full consideration of prenatal, perinatal and environmental factors which affect development, and on a careful developmental history, I have written separate chapters on these matters. I have placed particular emphasis on the normal variations which occur in all fields of development, and on the reasons for these variations. I have repeatedly emphasised the difficulties in developmental assessment, and the reasons why assessments in infancy can never have a high correlation with intelligence tests in older children, and still less with success in later life. I have discussed in detail the reasons for the limitations in developmental testing. Perhaps the most important chapter is the last one — on the pitfalls in developmental assessment. Prelims.indd xi 09/08/12 3:56 PM  xii Preface to the First Edition The limitations and fallacies must be known and understood. There is a rapidly increasing interest in the physiology and pathology of pregnancy in relation to the fetus, and attempts to correlate events in pregnancy with the development of the infant are liable to give entirely fallacious results unless the difficulties of developmental testing, its possibilities and its limitations, are fully understood. As in other kinds of research, one must avoid the mistake of making accurate analyses of inaccurate data. This book does not attempt to discuss the normal physical and emotional development of the child. I have confined the book to the study of the infant and preschool child. I wish to express my gratitude to Arnold Gesell and Catherine Amatruda, above all others, for giving me the privilege to work under them and for teaching me the fundamentals of child development, so that I could then continue to learn for the rest of my working life. R.S.I. Prelims.indd xii 09/08/12 3:56 PM  Contents Biography v Preface to the Tenth Edition vii Preface to the Ninth Edition ix Preface to the First Edition xi 1. Developmental Testing: An Overview 1 2. Prenatal and Perinatal Factors Relevant to Developmental Assessment and Diagnosis 19 3. Environmental Factors and Development 47 4. Abilities and Reflexes of the Newborn 69 5. Normal Development 92 6. Variations in the General Pattern of Development 138 7. Variations in Individual Fields of Development 156 8. The Developmental History 185 9. Head Circumference 193 10. Assessment of Maturity 208 11. The Neurological Examination of the Newborn Baby 234 12. The Examination of the Older Infant and Child 261 13. Interpretation 290 14. The Diagnosis of Intellectual Disability 313 15. The Association of Intellectual Disability with Physical Defects and Disease 322 16. The Diagnosis of Cerebral Palsy 344 17. Assessment of Suitability for Adoption 369 Summary and Conclusions 378 Index 381 Prelims.indd xiii 09/08/12 3:56 PM “This page intentionally left blank"  Developmental Testing: An Overview 1 Evolution of Developmental Testing Development is considered delayed when the impediment is more than two standard deviations below the mean in one or more of the developmental domains.1 An estimated 12–16% of children have a developmental disability.2 The current approach in primary-care paediatrics is to identify these children through developmental surveillance, a continuous process in which the clinician observes the infant, takes a developmental history and obtains the parental concerns. However, identification of children with developmental delays is ineffective when based solely on surveillance, and only less than 30% of children with disabilities are identified.3 A necessary step is developmental screening or, even better, a developmental testing—the process of systematically quantifying skills and thus identifying children with suspected delays. Developmental testing greatly improves the identification rate to 70–90%.4,5 As up to 95% of children from birth to 3 years of age report regularly to healthcare settings, which primarily involves pediatricians, it is important to recognise that primary care paediatricians are uniquely suited for the identification of infants and toddlers with developmental difficulties.6 Despite these knowledge, paediatricians do not frequently use developmental tests in the early identification of children with special needs.7 For an accurate developmental assessment, information from multiple sources (parents, teachers and other professionals) using different methods of determining progress (developmental history, current functioning by report and on specific tests) from a range of professionals (child psychiatrists, child or developmental psychologists, speech and occupational therapists) is required.8 I propose to give a brief outline of the development of intelligence testing. This chapter will give an overview of the role of a busy paediatrician in a primary-care clinic in assessing a child with suspected developmental need. For a more complete account, the reader should refer to textbooks of Developmental Psychology. Studies of Individual Children According to Goodenough, Tiedemann in Germany (1787) was the first to publish a detailed record of the development of one child, but it was not until  2 Illingworth’s The Development of the Infant and Young Child Charles Darwin9 in 1877 published a detailed account of the development of one of his own 10 children that interest was aroused. Charles Darwin wrote: 1 ‘My first child was born on December 27th, 1839, and I at once commenced CHAPTER to make notes on the first dawn of the various experiences which he exhibited, for I felt convinced, even at this early period, that the most complex and fine shades of expression must all have had a gradual and natural origin.’ He described the rooting reflex, hearing in the newborn period, the absence of tears in the first few weeks except when his coat sleeve accidentally caught his child’s eye, the first coordinated movements of the hands at 6 weeks, the cephalocaudal sequence of development, the reciprocal kick, hand regard at 4 months, the first sign of anger (at 10 weeks), of humour (at 3 months), of fear, imitation and of enjoyment of the sound of the piano (at 4 months). He described the first association of a person with her name (at 7 months), the first signs of jealousy, love, curiosity, association of ideas, deceit, moral sense, inhibitions, laughter, shyness, sympathy and handedness. He had already published his famous and fascinating book The Expression of the Emotions in Man and Animals,10 which incorporated some of these and many other observations on crying, sobbing, laughter and other emotions. In 1893, Shinn published one of the most complete records of a young baby’s development. In 1931, Shirley wrote an extremely full account of 25 children in their first 2 years. Developmental Tests—Historical Aspects According to Bayley,11 Binet’s original aim was to identify children who were unlikely to benefit from regular school instruction. Binet emphasised that test scores did not imply that all ‘intelligence’ is inherited, or that a low score merely indicates poor innate endowment, or that environmental factors were irrelevant. In 1912, Stern and Kuhlman suggested that a child’s relative status could be indicated by a ratio between his mental age and his chronological age—the intelligence quotient (IQ). The term developmental quotient (DQ) is used in case of toddlers and young children when the developmental age is measured in place of mental age. In the early part of this century, Arnold Gesell, while studying intellectually disabled children, began to think about the early signs of intellectual disability and so set about the study of the normal infant. In 1925, he established ‘norms’ on a small series of children, seen at monthly intervals: later he revised the norms on a large number of children. A large series of books followed, of which I consider the most valuable today are Developmental Diagnosis,12 and Biographies of Child Development. These established ‘norms’ of development, describing the development of infants and children from just after the newborn period to the age of 5 years. The philosophy of development, the technique of developmental testing and the interpretation of results are all discussed in detail in his books. Knobloch and Pasamanick12 and Knobloch and colleagues13 brought Gessell and Amatruda’s book up to date. In 1933, Bayley11 established ‘norms’ on a  Developmental Testing: An Overview 3 large number of children. In 1954, Ruth Griffiths14 tested 571 children aged 14 days to 24 months—up to 31 children in each monthly period. In 1967, the CHAPTER Denver study15,16 was published, based on a sample of over 1000 children, a sample, however, which was ‘selected’ and not representative of the country as a whole. A revised and abbreviated Denver screening test, taking 5–7 minutes, was later described.17 1 In Scandinavia, the Boel tests have proved popular and have been used in Denmark, Holland and Italy.18 The word ‘Boel’ is an acronym for the Swedish ‘blicken orienterar efter ljud’—‘look orients after sound’—and is a test for the visual, auditory and tactile sense, intended for infants aged 7–9 months. A red object is used to attract visual attention, and four bells attached to the tester’s fingers attract auditory attention. The Brazelton and Dubowitz tests for the screening of the newborn are discussed in Chapter 11. Importance of Knowledge of Normal Development A thorough knowledge of the normal should be just as much the basis of the study of children as is physiology and anatomy for medicine in general. It is an essential basis for the study of the abnormal and of disease. I believe that all concerned with the care and management of children should not only know the normal, but should also be thoroughly conversant with the very common normal variations, which do not amount to disease, and, just as important, should try to understand the reasons for those variations. In this book, I have tried to discuss these matters in detail. Value of Developmental Assessment Every parent wants to know whether his child is developing normally, especially if in a previous pregnancy there had been a miscarriage or stillbirth, or if the child had proved to be intellectually or physically disabled. If there was an infection, toxaemia or other illness in pregnancy, or difficulty delivery, it would be natural for parents to be anxious to know whether their new baby is developing normally. A family history of intellectual disability, cerebral palsy or other disability would heighten their anxiety. An elderly mother, with no other children, who has lost her husband or is separated from him, is likely to be unduly concerned about her child’s development. Developmental assessments of infants provide important information to the obstetrician with regard to the safety of special investigations, treatment and management in pregnancy or labour. The safety of in vitro fertilisation, chorionic villi sampling, amniocentesis and ultrasound, the safety of older drugs, such as anticoagulants and of newer drugs in pregnancy, the management of infections, illnesses, hypertension and toxaemia, the advisability of preterm induction of labour and the risks of postmaturity, the assessment of newer methods of foetal monitoring and of problems arising in labour, all depend largely on the effect on the foetus and his development after birth.  4 Illingworth’s The Development of the Infant and Young Child Developmental assessments provide vital information for the neonatologist, who has to face difficult ethical problems with regard to the resuscitation of 1 very low birth weight babies or of the infant thought to have suffered serious CHAPTER perinatal brain damage. He has to assess the risks of methods of management and treatment in the intensive care unit. A neonatologist must be more than a skilful technician: he must follow up and assess the product of his handiwork. The surgeon may need a developmental assessment when faced with the ethical problem of deciding whether he is justified in embarking on extensive or risky surgery for some major congenital anomaly when he suspects that a baby is seriously intellectually disabled. He may also need to obtain follow-up findings on intellectual development after specialised surgery for such conditions as craniostenosis, subdural effusion, or the use of hypothermia in surgery for congenital heart disease. The paediatrician needs to be able to assess a baby’s intellectual development when faced with sucking and swallowing problems in the newborn, backwardness in any field of development, or with a child of unusual appearance or behaviour. He may well be the first to recognise malnutrition, emotional deprivation, or child abuse—and later he will need to assess the results of such problems—so that he can determine how much of the damage is reversible (Chapter 3). By his full developmental examination he is able to make an early diagnosis of defects of vision or hearing, of subluxation of the hip or other disabilities that are treatable, and for which early diagnosis is important. In the older infant or preschool child, he should detect features such as clumsiness, or features of specific learning disorders, whose recognition is important for the school teacher. The paediatrician needs developmental assessment to observe the effect of treatment of metabolic disorders, exposure to toxic substances, convulsions, meningitis and many conditions that may cause brain damage (Chapter 2). By his developmental and physical examination, he makes an early diagnosis of disability not only for treatment but also for the purpose of counselling the parents. Later he will need his knowledge of development for the purpose of assessing educational needs and choice of school. In order to make a decision about suitability for adoption, developmental assessment is essential, but it must be made by an expert and not by a doctor inexperienced in the field. It is a tragic disaster if an infant is labelled as unsuitable for adoption, when he is normal (Chapter 17); and it is tragic for parents if an infant is said to be normal, when he is seriously disabled. Any diagnosis of intellectual disability should be made only by an expert. Though parents usually like to be informed as soon as possible if a child is disabled, it is a mistake even to air one’s suspicion to the parents unless one is sure, for it would cause untold anxiety. (But for telling adopting parents, see Chapter 17.) Not only do errors in developmental assessment cause great anxiety and unhappiness, but they may also lead to unnecessary investigation and treatment. However, when a disability is suspected, a proper counselling about the developmental assessment prior to and after the assessment by the clinician, in a culturally sensitive manner, often ameliorates anxiety and improves parental understanding as well as support.  Developmental Testing: An Overview 5 Developmental assessment is frequently of great importance for medicolegal purposes. Numerous claims are made against doctors or hospitals, on the CHAPTER grounds that a child’s intellectual or physical disability was caused by brain damage arising from negligence when he is found to be intellectually disabled or to have cerebral palsy; a plaintiff may blame the obstetrician for causing it during labour or delivery. The paediatrician needs to know the relevant 1 prenatal factors that tell a different story. A carefully written contemporaneous record of prenatal conditions, of proper management in pregnancy, of foetal monitoring in labour and of skilled management after birth may go a long way to the disposal of an unjustified claim. A plaintiff may ascribe a child’s handicap, epilepsy or other disability to vaccine damage, improper management of meningitis or hydrocephalus or other condition. Of even greater importance is the written evidence that before the vaccine or other assumed cause of the handicap, there were already firm indications of intellectual disability or other neurological deficit. For instance, a head circumference at birth, unusually small in relation to weight, or subsequent developmental lag or defective growth of head size, before the vaccine was given, would indicate a pre-existing intellectual compromise. Well-kept notes by the obstetrician, neonatologist, paediatrician, clinic doctor or health visitor may provide vital evidence in the law court. Screening or Specialist Assessment? I have no doubt that the developmental assessment by an expert is of great value; but the expert is likely only to see those children who are referred to him by another person because there is some doubt about a child’s normality. I believe that very rough developmental screening should be part of the examination of any infant and young child (except when he is ill, as, with an acute infection). Even in situation when the child is ill, if the developmental assessment can help make an informed decision on the treatment approaches, a parent-rated developmental assessment can be used. In Chapter 5, I have tried to summarise a few of the most important milestones and the ages at which they are usually passed; if they are not, the child should be referred for an expert opinion. Elsewhere I have summarised the minimal but essential items for screening.19 It is doubtful20 whether more detailed universal screening of all infants by purely objective tests is useful. I have repeatedly found that reasonably intelligent parents, when they have become anxious about some aspect of their child’s development, often have a good idea of how far the child has developed as compared with the average. Several papers reached the same conclusion.21,22 I am doubtful whether it is wise to give parents a questionnaire about their child’s development, to be filled in by them,23 because of the danger that they would misinterpret the development and experience unnecessary worry as a result. I have tried to avoid this danger by explaining for parents the essentials of development and the normal variations which are so common.24,25  6 Illingworth’s The Development of the Infant and Young Child Psychologist or Clinician? Different Attitudes 1 Psychologists and clinicians have a different approach to developmental diagnosis. CHAPTER The psychologist (and often the clinician) wants a unitary figure or score for his assessment. The psychologist seeks scientific accuracy, and therefore purely objective tests irrespective of the history (for example, of preterm delivery) and irrespective of the physical examination. He eschews diagnosis by clinical impression, which is so liable to be wrong. He can only use scorable items of behaviour. He pays little attention to the complexities of human development and the multitude of factors, other than innate intelligence, scoring them on a pass or fail basis. All items of development are likely to be rated as of equal importance. Ruth Griffiths, for instance, in her popular development testing scheme, scored each of five fields of development, added them, and divided by five, to obtain a final score, which is then compared with the age to give the intelligence quotient or developmental quotient. As Knobloch and Pasamanik wrote in their discussion,12 this IQ score is likely to be based largely on verbal and problem tests. They comment that it leads to the fallacy of regarding intelligence as a global entity, which does not differentiate the various types of intelligence, giftedness or disability. However, it should be mentioned that more recently the unitary concept of intelligence has given way to multiple intelligence model, and intelligence tests are being developed based on this construct. While it is prudent to consider compromised IQ or DQ as one of the many symptoms of certain syndromes during the clinical assessment, it is mandatory to quantify the intelligence or development for a formal diagnosis of Intellectual Disability using international standard diagnostic systems like the International Classification of Disease (ICD-10) or Diagnostic and Statistical Manual (DSM-IV-TR). Thus, a unitary figure or score becomes important in most legal contexts and situations requiring diagnostic confirmation. The clinician bases his diagnosis on the history, the physical and developmental examination, special investigations where relevant and on his interpretation of the result. He needs all this because there are numerous factors, prenatal, perinatal and postnatal, which profoundly affect development and are unrelated to the intellectual endowment with which he was born. Nevertheless, it is required of the clinician, in this era of evidence-based practice, to base the diagnosis of disability and the consequent impairment on definitive history, clinical findings and laboratory results to enable a tailored management plan. Despite the different approaches, it should be accepted that development is also a ‘moving target’ just as normal development is. Therefore, it is impossible to determine if there is a delay until that milestone fails to emerge or emerges only in a compromised manner. Caution should therefore be used in interpretation of clinical findings that are ambiguous. In order to try to understand development, one must know the innumerable factors that affect it. Hence in Chapter 2, I have outlined the many prenatal or perinatal factors that are highly relevant to a developmental diagnosis; and in Chapter 3, I have outlined the many environmental and other postnatal factors that are essential to understanding. For instance, one needs to know about  Developmental Testing: An Overview 7 various aspects of the home environment. If a mother keeps her baby off his feet (in the mistaken idea that if he bears weight on the legs, he may develop CHAPTER rickets, knock knee or bow legs), then on examination one would find that his weight bearing is unusually poor in relation to his age, but it does not reflect the baby’s intellectual potential. The clinician will try to assess, from the mother’s story, the rate of development— 1 because he wants to know if it is steady, slowing down or accelerating—and he wants to know various other aspects of development that she has observed, so that he can check his own objective findings against the mother’s observations. He needs to know about genetic factors, preterm delivery, illnesses in pregnancy or illnesses experienced by the child, drug-taking in pregnancy or drugs taken by the child, the amount of stimulation that she gives the child, the temperament and numerous other important factors. In Chapter 8, I have discussed the details of history taking. The clinician will conduct a full physical examination of the child in order to determine whether there are conditions, such as a visual or auditory defect, cerebral palsy or hypotonia, which will greatly affect development, but which is not directly related to his inborn intellectual endowment. The physical examination will include the measurement of the maximum head circumference in relation to his weight (Chapter 9). This is of vital importance in many developmental assessments. The clinician will perform a full detailed developmental examination in all fields. Chapter 4 discusses the normal features of the newborn, and Chapter 5 the normal features after the newborn period. Apart from his need for a detailed knowledge of normal development, he must understand the normal variations that are so common (Chapters 6 and 7). In Chapter 12, I have discussed the method of developmental testing in the older infant and child. In Chapter 13, I have discussed the interpretation of the results of all the above findings—the history, physical and developmental examination, and any tests which were done. The clinician will pay far more attention to some fields of development (e.g. responsiveness, alertness and concentration) than to others (especially gross motor development). He will then be in a position to determine how far the child has developed in relation to the average for his age, and so will arrive at the developmental quotient (DQ)—not necessarily in overall development, but often in separate fields of development. He knows, in arriving at such a score or scores, that the DQ is not static, but that it will be profoundly affected in the future by innumerable environmental factors, health, nutrition, the quality of the home, friends and school. Predictive Value Many psychologists insist that developmental assessment in infancy is of little or no value. Many studies have shown that there is only a slight correlation between tests in infancy and early childhood and later IQ scores. Yang,26 for instance,  8 Illingworth’s The Development of the Infant and Young Child reviewing the Gesell, Cattell, Bayley and Piaget tests, concluded that ‘they have proved to be systematically poor predictors of later performance’. It has been 1 suggested that the IQ of the parents is a better measure of a child’s potential CHAPTER than tests in infancy. This has been recently demonstrated with Griffiths’ mental development scales. It is said that this poor predictability could be because of the lack of development of skills in certain domains (verbal skills range possessed by toddlers compared to older children), which limits the comparability of the tasks in assessments at the two ages.27,28 I have indicated my view as to the reasons for these negative findings. Nearly all the studies were based on purely objective scorable tests which are of much less importance than other aspects of development which are difficult to score. Many of the items used have been inadequately defined (e.g. ‘walks well’): most of the studies have excluded all children who are the most likely to have an intellectual disability—the very ones in which developmental assessment is the easiest and in which there is likely to be a high correlation between scores in infancy and later IQ tests and the studies have ignored highly relevant factors, such as preterm delivery, environmental factors, cultural differences in child rearing, physical and sensory handicaps, head size in relation to weight and risk factors, such as the presence of other congenital anomalies. Clarke29 wrote that ‘the rather poor long-term predictions of normal development (except extreme, e.g. autism) are not inadequacies in our methods of assessment, but in development itself. But certain recent studies show that the poor predictive value could be attributed to methodological problem, like inadequate follow- up time.30 I believe that one of the reasons for the low correlation between test results in infancy and subsequent findings is exclusion of numerous categories of children in the establishment of norms.31 I have never understood the logic of establishing norms on a highly selected group of children—and in the process excluding the very children in whom prediction of future potential is so important, and in which prediction is so much easier than in the average child. In addition, intelligence develops with cognitive maturation and starts stabilising by 11 years of age, thus is an innate process as well (Chapter 6). Arnold Gesell’s norms were based only on Caucasian children from an apparently homogeneous group of parents of similar socioeconomic class. Children with a history of birth injury or other disease, or those who on follow- up were found to be abnormal, were excluded. The Denver Group16 excluded preterm or breech-born infants or children with a physical defect. Bayley11 chose for her norms a highly selected group of children from University parents: the mean IQ of the children at 9 years was 129. Beintema32 excluded all with low birth weight, preterm or otherwise, non-Caucasian children, all with physical abnormalities or serious neonatal disease. Brazelton33 was even more rigorous in exclusions. He did not include non-Caucasian children, preterm infants, those weighing 3175 g or less at birth, children born to mothers who had been given barbiturates, or had had possible intrauterine problems, children who needed special care in the newborn period or who had experienced some hypoxia. The  Developmental Testing: An Overview 9 Kansas Group34 excluded all with marked delay in one developmental area as compared with other areas. Others excluded twins. It follows that the norms CHAPTER were based on a specially selected group of children who were not representative of the population as a whole. It is not clear to me how those excluded could then be assessed. If one were to conduct a survey of haemoglobin levels in preschool children, it would seem irrational to exclude all children at risk of 1 anaemia—those born preterm, all non-Caucasian children, all with malnutrition and all from socioeconomically weaker groups. Other workers, especially those who have taken other relevant factors into account, have found that developmental tests in infancy are of value. Siegel, for instance,35 in a study of 80 preterm infants and 68 full-term infants found significant correlation between Bayley tests at 4, 8, 12 and 18 months with cognitive and language development at 2 years. He wrote that ‘infant tests, in conjunction with assessment of the child’s environment, appear to be useful in predicting developmental functioning and delay at 2 years’. I have summarised elsewhere the rationale of Arnold Gesell’s philosophy of development. I wrote, ‘It would seem reasonable to suppose that if careful detailed observation were made of the course of development of a sufficiently large number of babies, record being made of the age at which various skills were learned, it should be possible to establish some relationship between records so obtained and their subsequent progress through childhood. Though it is impossible to say what is ‘normal’, there is no difficulty in defining the ‘average’, and it should be easy to determine the sequence and rate of growth of the average child and to note the frequency with which deviations from the usual growth pattern occur as a result of known or unknown factors. Having determined the developmental pattern of average children, it should be possible to determine whether an individual child has developed as far as the average one of his age, taking into account all factors which might have affected his development. By making further examinations at intervals in order to assess his rate of development, and by taking into account all possible factors in the child and his environment which might affect the future course of his development, one ought to be able to make a reasonable prediction of his future progress provided that one knows the frequency of abnormal growth patterns. Arnold Gesell and his staff at the Yale Clinic of Child Development made much studies for 40 years or more, and they were convinced that such prediction is in fact possible.’ By 1930, Gesell estimated that he and his staff had examined more than 10,000 infants at numerous age periods. He wrote that ‘attained growth is an indicator of past growth processes and a foreteller of growth yet to be achieved’. He emphasised the ‘lawfulness of growth’ and said that ‘where there is lawfulness there is potential prediction’. He constantly called for caution in attempting to predict a child’s future development because of all the variables concerned. To use his words: ‘Diagnostic prudence is required at every turn’, and ‘so utterly unforeseen are the vicissitudes of life that common sense will deter one from attempting to forecast too precisely the development career of any child.’  10 Illingworth’s The Development of the Infant and Young Child I cannot agree that it is only the severe cases of intellectual disability which can be diagnosed in infancy. In a study at Sheffield we followed up 135 children who 1 were considered at any time in the first 2 years of life to be intellectually disabled, CHAPTER however slightly. Cases of Down’s syndrome, hypothyroidism, hydrocephalus and anencephaly were excluded. In 10 of the children, the intellectual disability was of postnatal origin, and in the others it was of prenatal or natal origin. Apart from these exclusions, the cases were in no way selected, in that we included all children thought by me or my staff to be retarded—even though one or two very shortly after the initial assessment were subsequently thought to have reverted to normal. The initial diagnosis was based on a clinical assessment in the out- patient department, using some of the Gesell tests, with full consideration of the developmental history and other data. All but two of the survivors were traced and re-examined, using for the most part Terman and Merrill tests at the age of 5 years or later. All but five of them were retarded. In 77 the initial diagnosis was made in the first year, and in 59 it was made in the second year. A total of 34 had died. In all 10 on whom autopsies were performed, gross anomalies of the brain were present. Of the 101 survivors who were traced, 59 on follow-up examination were seriously subnormal (IQ score below, 50), 25 had an IQ score of 50–75, 13 had an IQ score of 76–94 and four had an IQ score of 100 or more. I have referred to those in Chapters 6 and 7. Of 67 who were thought to be severely subnormal in infancy, 55 on follow-up examination were found to be seriously subnormal (ESN.S.) Of 20 who were regarded as only slightly retarded in infancy, only two on follow-up examination were found to be seriously subnormal. The figures indicate that intellectual disability can be confidently diagnosed in the first 2 years, apart from the obvious forms, such as Down’s syndrome. For practical purposes this is the most important function of developmental tests. It does not matter much whether a baby has a developmental quotient of 110 or 130, but it matters a great deal for purposes of adoption if his developmental quotient, being 70 or less, suggests that the child is going to be intellectually disabled in later years. At the Children’s Hospital, Sheffield, infants were examined every week for the purpose of assessment for suitability for adoption. They were seen by me personally in their first year, at the age of 6 weeks or 6 months. On the basis of tests described in this book they were graded as follows: Grade 1 Possibly above average Grade 2 Average Grade 3 Possibly below average Grade 4 Inferior When they reached school age they were examined by psychologists or School Medical Officers (who knew nothing of my grading), IQ test scores being made on the basis of Terman and Merrill and other methods. The following were the mean IQ scores at school for each of the grades allotted in infancy. The total number of children followed up and tested at school age was 230. Five additional babies could not be followed up because of emigration or  Developmental Testing: An Overview 11 Table 1.1: Grading in infancy in relation to IQ at school age Grading allotted in infancy Total Mean IQ at 5–8 years CHAPTER 1 69 111.5 2 92 108.0 3 54 94.9 1 4 15 76.0 Table 1.2: Grading in infancy in relation to IQ at school age Grade in łrst year 1 (total 69) 2 (total 92) 3–4 (total 69) IQ at school Below 80 1 (1.5%) 1 (1.1%) Over 120 1 (1.5%) because they could not be traced: otherwise the series was complete. Table 1.1 shows the grades allotted in infancy and the mean IQ at age 5–8 years. Table 1.2 shows the scores allotted in infancy to children who proved later to have a high or low IQ score. Only one child placed in Grade 1 and one in Grade 2 subsequently had an IQ below 80 (actually 79 and 69, respectively). One child in Grade 3 had an IQ of 132. The differences between Grades 2 and 3, and 3 and 4 were significant at the 0.1% level. It should be noted that in the earlier part of this investigation the assessment was rendered more difficult by the fact that the infants had been in an institution for the first 6 months of their life, and came direct from it, so that there was the factor of emotional deprivation which would have delayed their development. It was not possible to decide how much delay had been caused by this factor and how much of it would be reversible. The institution was subsequently closed, the infants being placed in foster homes at the age of 9 or 10 days. The figures support the contention that intellectual compromise can be diagnosed more easily than intellectual superiority. One is more likely to underestimate potential than to overestimate it. Others have made similar observations. A Johns Hopkins study36 indicated that a trained pediatrician can accurately diagnose developmental disabilities before the age of 12 months; there was a good correlation between the early diagnosis of cerebral palsy and intellectual disability in the first year with subsequent findings. There were very few false diagnoses. Others37 showed that CNS signs in the first year correlate with learning problems at school at 7 years of age. I have little statistical evidence from my own work that intellectual superiority can be diagnosed with reasonable confidence in infancy. Some of the workers quoted have adduced evidence to that effect. But the fact that intellectual disability can be diagnosed in infancy indicates that developmental tests, in this important practical matter at least, do have a definite predictive value. Knobloch rightly pointed out that the principal function of developmental tests in infancy is the detection of abnormal neurological conditions and of  12 Illingworth’s The Development of the Infant and Young Child compromised developmental potential. She added that these tests are not intended to detect intellectual superiority or precise IQ scores later. Although 1 a small percentage may be considered superior, the question of whether they CHAPTER remain so depends on their later experiences. She added that ‘As clinicians we would feel that an examination which would allow us to make the following statement is an eminently acceptable and useful tool. This infant has no neurologic impairment, and his potential is within the healthy range: depending on what his life experiences are between now and 6 years of age, he will at that time have a Stanford–Binet IQ above 90, unless qualitative changes in the central nervous system are caused by noxious agents, or gross changes in milieu alter major variables of function, and the studies that we have done indicate that when care is taken to eliminate bias and the infant examination is used as a clinical neurological tool by a physician adequately trained in its use, good correlations are obtained. These studies have not been challenged by the critics of infant evaluation, they have merely been ignored. In short, clinicians should select developmental measures based on the defined purpose of the measure, training and experience of the clinician, age range covered by the measure, administration and scoring time, developmental domains encompassed and comparability of the standardisation sample with the children being assessed. Finally, it is important that caution be exercised in using tests for predicting the risk of developmental problems in infants and toddlers unless the tests have acceptable levels of diagnostic accuracy and other psychometric properties.38 Developmental Assessment Measures Hundreds of assessment measures are available across the world for developmental assessment, and no governmental agencies or scholarly societies regulate the quality of these measures or prevent tests of poor quality from being advertised and sold. Therefore, clinicians must be familiar with measures to select the ones with appropriate levels of diagnostic accuracy. The measures available to assess the development of a child may be clinician rated or parent rated. Measures that draw on information that is reported by the parents may be more suitable for primary care paediatric settings than those that require direct observation or elicitation of developmental skills. Such tests can be self-administered in waiting or examination rooms, attached to an appointment later, administered online before an appointment, or delivered by interview in person or over the telephone. Such tests are usually less expensive, take only a few minutes of professional time to interpret, eliminate the challenge of directly eliciting skills from children who may not demonstrate the best effort on the day of testing. In addition, parent- rated tests provide a family-focused and collaborative approach to monitoring development and addressing developmental problems.39–41 Ages and Stages Questionnaires, Brigance Screens-II, Parents’ Evaluations of Developmental Status and Infant–Toddler Checklist for Language and Communications are some of the parent-rated measures with fairly good diagnostic accuracy. The clinician may rate based on the direct observation of the child and may acquire  Developmental Testing: An Overview 13 parental information to further support his observations. As this approach primarily relays on direct observation or elicitation of skill, it requires several CHAPTER attempts to optimise test conditions. Clinician-rated tests are used by clinicians who have a particular interest in developmental problems, to complement the results of parent-report measures, to explore an area of concern in greater depth, or to enhance their relationship with the family and child to make 1 appropriate decisions and referrals. Gessell’s Developmental Schedule, Bayley Infant Neurodevelopmental Screener, Denver Developmental Screening Test, Developmental Activities Screening Inventory, Battelle Developmental Inventory, Developmental Assessment of Young Children, Developmental Profile, Merrill- Palmer Revised Scales of Development, Griffiths Developmental Scales, Mullen Scales of Early Learing are some of the clinician-rated measures with normative data to support their results. For further information on reliable and easy to use measures, the readers are recommended to read the articles by Glascoe and Hamilton.42,43 Developmental Prediction: What We Can and Cannot Do Everyone who attempts to assess the development of babies should be fully conversant with the limitations of developmental prediction. Below I have summarised what we can hope to do and what we must not expect to be able to do. What we can do (but not necessarily in the earliest weeks) is as follows: 1. We can say how far a baby has developed in relation to his age, and we can therefore compare him with the average performance of others at that age, and we can say something about his rate of development. By so doing we can say something about his developmental potential. 2. We can diagnose moderate or severe intellectual disability. 3. We can diagnose moderate or severe cerebral palsy. 4. We can assess muscle tone. 5. We can diagnose moderate or severe deafness. 6. We can diagnose moderate or severe visual defects. 7. We can diagnose subluxation or dislocation of the hip. 8. We can diagnose neurological defects in infancy. 9. As a result of our developmental and neurological examination, we are in a better position to give genetic counselling. What we cannot do is as follows: 1. We cannot draw a dividing line between normal and abnormal in the early infancy. All that we can say is that the further away from the average the child is in anything, the more likely he is to be abnormal. 2. We cannot make accurate predictions of his future intelligence and achievements, because these will be profoundly affected by environmental and other factors in the future. There never will be a high correlation between developmental assessment in infancy and subsequent intellectual achievement.  14 Illingworth’s The Development of the Infant and Young Child 3. We cannot eliminate the possibility that he will undergo intellectual deterioration in future months or years. 1 4. If he has suffered severe emotional deprivation before we assess him, we CHAPTER cannot assess at one examination the extent of the damage which he has suffered, or its reversibility. 5. If he is retarded and has no microcephaly, we cannot be sure that he is not a slow starter (delayed maturation). 6. If he was a low birth weight baby and we do not know the duration of gestation, we cannot tell after the newborn period whether we should allow for prematurity or not—though the motor nerve conduction time will guide us in this. 7. We cannot make a sensible prediction for a full-term baby at birth or in the first 4 weeks unless there are grossly abnormal signs and still less can we made a valid assessment of a prematurely born baby until after due correction for prematurity he has reached at least 4–6 weeks of age. For instance, if he was born 8 weeks prematurely, it would be unwise to assess him until at least 12–14 weeks after delivery. 8. We cannot rely on diagnosing mild cerebral palsy or mild intellectual disability in the early weeks. 9. If we find abnormal neurological signs in the first few weeks we cannot be sure unless they are gross that they will not disappear and if they disappear, we cannot be sure that when he is older, at school age, the finer tests of coordination and spatial appreciation then available will not show that there are in fact some residual signs, such as clumsiness. The older the infant, the less likely it is that abnormal signs will disappear and after the first year it is unlikely that they will be anything but permanent. 10. We cannot eliminate in infancy the possibility that the child will subsequently display specific learning disorders, or difficulties of spatial appreciation. 11. We cannot translate into figures Gesell’s ‘insurance factors’—the baby’s alertness, interest in his surroundings, social responsiveness, determination and powers of concentration—features which are of much more predictive value than the readily scorable items, such as gross motor development or sphincter control. Without special equipment we cannot score the quality of his vocalisations—and they are important. However, many of the factors like ability to concentrate and motivation to take on the test are noted in most of the test by the psychologists as general observations. 12. We cannot say what he will do with his talents or with what we have termed his developmental potential (See Chapter 13). 13. We cannot prove, in any but exceptional cases, that a child’s cognitive or neurological deficits are due to birth injury rather than to prenatal causes. 14. We cannot normally predict intellectual superiority. Finally, it must be remembered that there are many aspects of ability; they include verbal, numerical, spatial, perceptual, memorising, reasoning, mechanical and imaginative qualities. It would hardly be likely that tests in infancy would detect these with a high degree of reliability.  Developmental Testing: An Overview 15 Dangers of Developmental Assessment CHAPTER I wrote elsewhere that many people are now assessing babies without knowing why they are doing it, how to do it, or what to do when they have done it. I would now add that many do not realise what harm they can do by developmental assessment. 1 One obvious danger is a wrong diagnosis—consisting either of passing a baby as normal when he is not, or incorrectly saying that he is abnormal. If a baby is passed as normal for adoption, so that he is adopted without the adopting couple knowing that he is handicapped, it is a tragedy for the adopting couple and it may be a tragedy for the child, for it may lead to rejection. It is major tragedy for a child who is prevented from being adopted on the grounds that he is abnormal, when in fact there is nothing wrong with him (Chapter 17). I have heard of health visitors in two cities ‘failing’ 40% of babies in the 6-month assessment and telling the mothers that the babies had failed. I have seen mothers upset when a nurse has said ‘Isn’t he sitting yet?’ ‘Her head is small.’ ‘Hasn’t he got a big head?’ I have heard of babies in an 8-month assessment being referred to a psychiatrist because of supposed backwardness! A 5-month-old baby who was brought to a paediatrician for assessment for adoption was said to have a spastic arm. As a result the foster mother began to imagine that the arm was spastic, postponed adoption and then decided not to adopt. The child was normal and had nothing wrong with him. It was not until he was 4 years old that after great difficulty adoption was arranged; in the meantime this bright normal child had suffered the psychological trauma of repeated changes of mother. I have seen many children wrongly said to be spastic, intellectually disabled or hydrocephalic, when there was nothing wrong with them: the wrong diagnosis had caused inestimable suffering. One mother was told by a doctor ‘Your child may be a spastic, but don’t worry.’ Fortunately I was immediately asked to see the intensely worried mother, and examining the baby on the next day found an intellectually superior normal baby with no trace of spasticity. Mothers want to know and have a right to know as soon as possible if their child is disabled, but there are many occasions when one is doubtful whether the young infant has an abnormality or not. Unless there is an available treatment (as for hypothyroidism, or subluxation of a hip) one should say nothing until certain. If treatment is available, and special investigation is required, then the mother must be told. A couple wishing to adopt a child must be told if there is doubt about the baby; they may have to delay adoption so that one can see the child again for reassessment before the adoption is clinched. Otherwise if there is no necessary treatment available, nothing should be said until a firm decision has been made. The doctor must use his ingenuity in arranging so and see the child again without causing distress. If it is thought that there are doubtful signs of cerebral palsy, then no harm will be done by waiting to re-examine the child before telling the parents, if it is so mild that one cannot be sure, no treatment will make any difference and no harm can be done by waiting. I have repeatedly seen  16 Illingworth’s The Development of the Infant and Young Child much distress by a doctor’s or nurse’s unwise expression of doubts about a baby. 1 The mere name of the ‘assessment clinic’ may alarm mothers. I believe that CHAPTER developmental assessment is just part of the routine examination of a baby anywhere—in a child health clinic, hospital or home, and that the only place for the so-called assessment clinic is for the overall assessment of a child with disability by all the relevant specialists. Summary For many reasons, developmental assessment is an essential part of paediatric practice. The basic essentials for it are a thorough knowledge of the normal, of the normal variations and the reasons for those variations. All clinical diagnoses should be based on the history, the examination and the interpretation of the history and findings on examination. The history must include all prenatal, perinatal and postnatal factors which profoundly affect development, most of which are not directly related to the child’s intellectual endowment. Of particular importance is preterm delivery, for it is essential to allow for prematurity when assessing development. The examination will include full physical examination, including the head circumference in relation to weight, the assessment of vision and hearing, and other physical factors which affect development. Purely objective tests, without attention to the history and full physical examination, inevitably omit factors of the greatest importance for assessment. All persons carrying out developmental assessment should understand its great value, its predictive importance and its limitations which are largely due to the many variables which alter the course of development. Unwise comments to parents about a child’s development will cause great anxiety. References 1. McDonald L, Rennie A, Tolmie J, Galloway P, McWilliam R. Investigation of global developmental delay. Arch Dis Child. 2006;91:701–5. 2. Glascoe FP. Early detection of developmental and behavioral problems. Pediatr Rev. 2000;21:272–9. 3. Smith RD. The use of developmental screening tests by primary care pediatricians. J Pediatr. 1978;93:524–7. 4. Squires J, Bricker D, Potter L. Revision of a parent-completed development screening tool: Ages and Stages Questionnaires. J Pediatr Psychol. 1997;22:313–28. 5. Rydz D, Shevell MI, Majnemer A, Oskoui M. Developmental screening. J Child Neurol. 2005;20(1):4–21. 6. Zuckerman B, Parker S. New models of pediatric care. In: Halfon N, Schuster M, eds. Child Rearing in America. New York, NY: Cambridge University Press; 2002. 7. King TM, Tandon SD, Macias MM, et al. Implementing developmental screening and referrals: lessons learned from a national project. Pediatrics. 2010;125(2):350–60.  Developmental Testing: An Overview 17 8. Bolton P. Developmental assessment. APT 2001;7:32–42. 9. Darwin C. A biographical sketch of an infant. Mind. 1971;2:285 (See Dev Med Child CHAPTER Neurol. 1944; Supplement 24). 10. Darwin C. The Expression of the Emotions in Man and Animals. London: Murray; 1872. 11. Bayley N. Mental growth during the first three years. Genet Psychol Monogr. 1933;14:1. 12. Knobloch H, Pasamanick B. Gesell and Amatruda’s Developmental Diagnosis. 3rd ed. Hagerstown, MD: Harper and Row; 1974. 1 13. Knobloch H, Stevens F, Malone A. Manual of Child Development. Hagerstown, MD: Harper and Row; 1980. 14. Griffiths R. The Abilities of Babies. London: University of London Press; 1954. 15. Frankenburg WK, Camp BW, van Natta PA, Demers-Seman JA, Voorhees SF. Validity of the Denver developmental screening test. Child Develop. 1971;42:475. 16. Frankenburg WK, Dodds JB. The Denver developmental screening test. J Pediatr. 1967;71:181. 17. Frankenburg WK, Fandal AW, Sciarillo W, Burgess D. The newly abbreviated and revised Denver developmental screening test. J Pediatr. 1981;99:995. 18. Junker KS, Barr B, Maliniemi S, Wasz-Hockert O. BOEL—a screening program to enlarge the concept of infant health. Paediatrician. 1982;11:85. 19. Illingworth RS. Basic Developmental Screening. 3rd ed. Oxford: Blackwell; 1982. 20. Carmichael A, Williams HE. Developmental screening in infancy—a critical appraisal of its value. Aust Paediatr J. 1981;17:20. 21. Coplan A. Parental estimate of child’s developmental level in a high risk population. Am J Dis Child. 1982;136:101. 22. Keshavan MS, Narayanan HS. Parental estimation of child’s developmental level. Am J Dis Child. 1983;137:87. 23. Frankenburg WK, Van Doorninck WJ, Liddell TN, Dick N. The Denver prescreening developmental questionnarie (PDQ). Pediatrics. 1976;57:744. 24. Illingworth RS. Your Child’s Development in the First Five Years. London: Churchill Livingstone; 1981. 25. Illingworth RS, Illingworth CM. Babies and Young Children. 7th ed. London: Churchill Livingstone; 1983. 26. Yang RK. Early infant assessment, an overview. In: Osofsky JD, ed. Handbook of Infant Development. New York: Wiley Interscience Publications; 1979. 27. Lung FW, Shu BC, Chiang TL, Chen PF, Lin LL. Predictive validity of Bayley scale in language development of children at 6-36 months. Pediatr Int. 2009;51(5):666–9. 28. Sutcliffe AG, Soo A, Barnes J. Predictive value of developmental testing in the second year for cognitive development at five years of age. Pediatr Rep. 2010;2(2):e15. 29. Clarke ADB. Predicting human development. Problems, evidence, implications. Bull Br Psychol Soc. 1978;31:249. 30. Valentini NC, Saccani R. Brazilian validation of the Alberta Infant Motor Scale. Phys Ther. 2012;92(3):440–7. 31. Illingworth RS. Norms for development. Dev Med Child Neurol. 1986;28:122. 32. Beintema DJ. A neurological study of newborn infants. Clinics in Developmental Medicine No. 28. London: Heinemann; 1968. 33. Brazelton TB. Neonatal behavioral assessment scale. Clinics in Developmental Medicine No. 50. London: Heinemann; 1964. 34. Holmes GE, Hassanein RS. The kid’s chart. Am J Dis Child. 1982;136:997. 35. Siegel LS. Infant tests as predictors of cognitive and language development at two years. Child Dev. 1981;52:545. 36. Farber JM, Shapiro BK, Palmer FB, Capute AJ. The diagnostic value of the neurodevelopmental examination. Clin Pediatr (Phila). 1985;24:367.  18 Illingworth’s The Development of the Infant and Young Child 37. Denhoff E, Hainsworth P, Hainsworth M. The child at risk for learning disorder. Clin Pediatr (Phila). 1972;11:164. 1 38. Lee LL, Harris SR. Psychometric properties and standardization samples of four screening CHAPTER tests for infants and young children: a review. Pediatr Phys Ther. 2005;17(2):140–7. 39. Glascoe FP, Foster EM, Wolraich ML. An economic analysis of developmental detection methods. Pediatrics. 1997;99:830. 40. Glascoe FP. Screening for developmental and behavioral problems. Ment Retard Dev Disabil Res Rev. 2005;11:173. 41. Dworkin PH. Detection of behavioral, developmental, and psychosocial problems in pediatric primary care practice. Curr Opin Pediatr. 1993;5:531. 42. Glascoe FP. Screening for developmental and behavioral problems. Ment Retard Dev Disabil Res Rev. 2005;11(3):173–9. 43. Hamilton S. Screening for developmental delay: reliable, easy-to-use tools. J Fam Pract. 2006;55(5):415–22. Prenatal and Perinatal Factors Relevant to Developmental 2 Assessment and Diagnosis A child’s developmental level is the end result of wide variety of factors: prenatal, perinatal and postnatal. In establishing a developmental diagnosis, one must be thoroughly conversant with these factors. In this chapter, I shall attempt to summarise those prenatal and perinatal factors that I think are particularly relevant in the interplay of nature versus nurture. Preconception: Genetics Prenatal factors operating before conception include the intelligence, personality, education and attitudes of the parents, and the way in which they were brought up. As for intelligence, it has even been suggested that because it was found that the coefficient of correlation of intelligence tests of husbands and wives was as high as that of brothers and sisters, the intelligence quotient (IQ) of parents may be a good guide to an infant’s intelligence. In case the IQ of an infant needs to be quantified, measures like the Fagan’s Intelligence Test for Infants1 can be used by trained psychologists. Sir Francis Galton in 1869 was one of the first to study the genetics of intelligence. He made the observation that 977 eminent men had 535 eminent relatives, as against a total of four eminent relatives amongst 977 ordinary men. Terman and Oden followed up 1528 children with an IQ of 140 or more. Three hundred and forty-eight of their children had a mean IQ of 127.7. The number with an IQ of 150 or more was 28 times that of unselected persons. The most studied aspect of intelligence is the heritability of intelligence, and about 50% of a child’s intelligence is considered inherited.2 The heritable factor of intelligence—‘intelligence A’, as distinct from ‘intelligence B’, which is intelligence A modified by environmental factors—has been studied by comparing the intelligence of children placed in foster homes with that of their real and adopting parents. In these adoption studies, there was no correlation between the child’s IQ and that of the biological mother at first, but there was  20 Illingworth’s The Development of the Infant and Young Child increasing correlation with advancing age, presumably because of genetic factors. More recently, it is documented that heritability of intelligence is estimated to increase with age with 20% in infancy, 40% in childhood and 60% or greater in later life.3 It has been said that the correlation of IQ between biological children and their parents was twice as high as it was between adopted children and adopting parents, whether or not the biological parents raised them.4 The genetic aspect of intelligence has also been investigated by the method of studying identical twins reared apart, though an obvious fallacy of such studies lies in the possibility that similar foster parents might be chosen for identical twins. 2 The IQ of identical twins reared apart is more correlated than that of fraternal CHAPTER twins reared in the same home; but the environmental factor determines the extent to which the genetic potential is realised. It is strange that retinoblastoma, myopia, asthma and high serum uric acid levels are associated with a high IQ. In the case of myopia, it is said that children show a higher than average IQ before the myopia develops.5 A Swiss paper6 studied 23 patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency, comparing them with 27 unaffected siblings and 48 parents. The patients and siblings had a significantly higher IQ score than average, but the parents did not. Overall, it is understood that same genes may be responsible for diverse cognitive and physical phenotypes in children.7 Before one can give genetic advice in a case of intellectual disability, full investigation is essential in order that one can detect metabolic and other forms of intellectual disability with a known genetic pattern. For instance, if a child is found to have one of the recessive forms of intellectual disability, such as phenylketonuria or Tay-Sach’s disease, the risk of another child being affected is 1 in 4; while for non-specific forms of intellectual disability, the risk is of the order of 1 in 30. Chromosomal studies are necessary before one can give genetic advice in the case of Down’s syndrome. The overall risk of a child with Down’s syndrome being born is 0.15%, rising to 4% (1 in 25) for a mother of 45 years; but if a mother under 25 had a chromosomal translocation, there is a 7–10% chance that her child will have Down’s syndrome or carry the translocation.8,9 In the unlikely case of a woman with Down’s syndrome becoming pregnant, there is approximately one in two chances that the child will be normal. It was our practice at the Children’s Hospital, Sheffield, to perform a 48-hour ‘work up’ on all intellectually compromised infants, largely in order that genetic advice could be given, and partly to institute appropriate treatment, if possible. The investigation included plasma and urine amino acids, fasting blood glucose, blood calcium, phosphorus, sodium, potassium, bicarbonate, urea, phenylalanine, Wassermann’s reaction, motor nerve conduction time, karyo type, and where relevant blood lead, urine homovanillic acid and tests for thyroid function. The outlook for a child of a parent with intellectual disability is not as gloomy as was once thought. Skodak10 studied 16 children whose mothers were feeble minded, with a mean IQ of 66.4, and found that the mean IQ of the children was 116.4. In my own study of babies seen for adoption purposes, 22 children of certified intellectually compromised mothers had a mean IQ of 100.1. This is less than the average IQ for adopted children (Chapter 3).  Prenatal and Perinatal Factors 21 Hereditary conditions related to development include gross anomalies of the central nervous system. The risk of a child being born with a gross anomaly of the central nervous system when the parents are normal is 3%. When the parents are normal, the risk of having a child with hydrocephalus alone is 1 in 2000, and of having a child with hydrocephalus and spina bifida is 1 in 3000. It has been found that the risk of a subsequent child being affected with hydrocephalus, spina bifida or anencephaly is about 2–4%. If two affected infants are born, the risk is even greater. In the case of epilepsy, the risk of a normal parent having an epileptic child is 1%11; if one is affected, the risk of another CHAPTER being abnormal is 2–5%.12 The risk of an affected parent having an affected child is 2.4–4.6%.11 If the affected parent is mother, the risk to the offspring developing epilepsy is 2.8–8.7%; if the affected parent is father, then the risk is 2.4%. About 3.2% of parents, siblings or children of epileptic patients have fits.13 There is a genetic factor for cerebral palsy, apart from that in kernicterus due to 2 blood group incompatibility. In my series of 760 children with cerebral palsy, excluding kernicterus, 4% had an affected sibling. (Kernicterus is also caused by hyperbilirubinaemia resulting from neonatal septicaemia: kernicterus due to prematurity is now rarely seen because of improved care.) It is now believed that up to 10% of cerebral palsy is the consequence of chromosomal anomalies and continuous gene syndromes. Acquired chromosomal abnormalities develop postnatally, affect only one clone of cells, resulting in cerebral palsy. On the other hand, in continuous gene syndromes constitutional abnormalities develop during gametogenesis or early embryogenesis and affect a significant portion of the child’s cells resulting in cerebral palsy.14 Routine cytogenetic testing although is expensive in most settings, some authors believe, is indicated in the evaluation of the child with developmental delay even in the absence of dysmorphic features or clinical features suggestive of any specific syndrome.15 Metabolic Diseases Hereditary metabolic defects include in particular diabetes mellitus, hypothyroidism, phenylketonuria and Lesch–Nyhan’s syndrome. Maternal diabetes is associated with an increased risk of foetal anomalies, including sacral agenesis. Currently, it is understood that the risk of major malformations increases in infants of diabetic mothers, ranging from 4% to 10%, which is 2–3- fold higher than in the general population. The risk for specific malformations like neural tube defects is even higher amongst this population.16 Amongst children of mothers with pre-existing diabetes, the incidence of cardiovascular abnormalities ranges from 2 to 34 per 1000 births, central nervous system abnormalities from 1 to 5 per 1000 births, musculoskeletal abnormalities from 2 to 20 per 1000 births, genitourinary abnormalities from 2 to 32 per 1000 births, and gastrointestinal abnormalities from 1 to 5 per 1000 births.17,18 It has been suggested that the level of thyroid hormone in women with thyroid disease is a factor related to the motor and cognitive competence of their children.19 It is demonstrated that lower maternal free T4 concentration at  22 Illingworth’s The Development of the Infant and Young Child 12 weeks’ gestation was associated with an impaired psychomotor development of the infant at 10 months of age.20 Similarly, in the children of mothers with untreated hypothyroidism during pregnancy, the IQ was 4–7 points lower than that of the children of mothers with normal thyroid functions.21 There is also inverse relationship between severity of maternal hypothyroidism and IQ of the offspring.22 In a review of the effect of maternal phenylketonuria on the foetus,23 involving 524 pregnancies in 155 women, it was emphasised that the child’s prospects depended largely on the time when the low phenylalanine diet was instituted, 2 and the level of phenylalanine in the pregnancy. Ninety-five per cent of mothers with a blood phenylalanine above 20 mg/L had at least one intellectually disabled CHAPTER child. While a child born with phenylketonuria can be treated by early dietary intervention, the damage caused to the foetus by the mother’s circulating high phenylalanine is irreversible.24 In addition, amongst the children of mothers with uncontrolled maternal phenylketonuria, 10% have congenital heart disease, 73% have microcephaly and 2% have major bowel anomalies.25,26 The purine metabolism disorder of Lesch–Nyhan syndrome is an X-linked disorder caused by variations in the hypoxanthine-guanine phosphoribosyl transferase 1 gene mutation with significantly different clinical presentations.27 In this self-mutilatory syndrome with intellectual disability, motoric symptoms and hyperuricaemia, the risk to siblings depends on the carrier status of the mother. Mothers who are carriers have a 50% chance of transmitting the diseases- causing gene in each pregnancy. Sons who inherit the mutation will be affected; daughters who inherit the mutation are carriers. Thus, during each pregnancy, a carrier mother has a 25% chance of having an affected boy, a 25% chance of having a carrier girl and a 50% chance of having an unaffected boy or girl. Prenatal testing in cases of increased risk may be useful, if the disease-causing mutation in the family is known.28 Chromosomal Abnormalities Many hereditary diseases are related to chromosomal defects, such as that in Turner’s syndrome or Down’s syndrome.29 In a Swedish study of intellectual disability,30 29% of cases of severe disability and 4% of milder disability were of chromosomal origin; 4% of severe disability and 10% of slight compromise in boys were associated with the fragile X syndrome. Five per cent were due to inborn errors of metabolism. The role of the fragile X in intellectual disability has been greatly understood now. Fragile X syndrome is the most common genetic cause of intellectual disability with autism that is inherited in an atypical X-linked dominant transmission. This syndrome is due to an increase in translation of proteins that are normally down-regulated by fraX mental retardation 1 gene repressor activity. Hereditary factors are also concerned with the child’s temperament and personality, though the inherited characteristics are profoundly affected by his environment. Approximately 50% of general cognitive ability of children is explained by the environment. This influence gradually decreases with age,  Prenatal and Perinatal Factors 23 from infancy to adulthood. Amongst the two types of environments, shared environment acts predominantly on children and non-shared environment on adults.31 The environmental influence on child development is discussed in Chapter 3. Other genetic factors include hereditary disease, and a tendency to premature or postmature delivery. The parents’ own childhood, the amount of love which they received and the way in which they were punished is likely to have an effect on their child rearing and parenting. Children subjected to corporal punishment are likely to use the same method on their own children in later years.32 Children who are CHAPTER happy and loved are more likely themselves to have h