Teratogenicity and Birth Defects

Teratogenicity

• Most common cause of birth defects in children is multifactorial.
• First month of pregnancy (preimplantation) exposure causes embryonic lethality.
• Pre-organogenesis (end of 1-2 months) causes morphological defects.
• Fetal second and third trimester cause functional disorders, growth retardation, and carcinogenesis.
• Folic acid deficiency can cause neural tube defects.
• Anticonvulsants, hyperthermia, trimethoprim, and valproic acid can cause developmental problems.
• Corticosteroids can result in cleft palate and adrenal atrophy.
• Diabetes mellitus may cause polycythemia, cardiomyopathy, and hypoglycemia.
• Tetracycline can lead to enamel dysplasia.
• Warfarin can cause nasal hypoplasia.
• Systemic lupus can cause congenital heart block.
• Rubella, phenylketonuria, and lithium can cause mental retardation and patent ductus arteriosus.
• Syphilis and retinoids can cause hydrocephalus.
• Rubella can cause microcephaly (but not macrocephaly).
• Streptomycin can cause deafness.
• Anti-epileptics like sodium valproate can cause neural tube defects.
• Thalidomide causes phocomelia.
• Diabetes mellitus can cause respiratory distress syndrome.
• Anti-parasitics like metronidazole are generally safe during the second and third trimesters.
• Varicella zoster (chicken pox) can cause developmental issues.

Care of Newborn

• Very low birth weight is less than 1500 grams.
• Low birth weight is less than 2.5 kg.
• Apgar score of 7 or higher in the 5th minute indicates healthy condition.
• Case studies illustrating varying conditions (heart rate, response to stimuli, etc.) and corresponding Apgar scores.
• Large for gestational age: baby's weight above 90th percentile.
• Post-term newborn: gestational age more than 42 weeks.
• Low birth weight: weight below 2500 grams.
• Average birth weight: at the 50th percentile.
• Small for gestational age: weight below 10th percentile.
• Preterm newborns: born before 37 weeks.
• Neonatal examination includes reflexes like tonic neck reflex, important risk factors (e.g., intraventricular hemorrhage), Erb's palsy, cephalhematoma, and primitive reflexes.

Neonatal Examination

• Reflex development in the first month is crucial.
• Tonic neck reflex.
• Critical risk factors, like intraventricular hemorrhage, can cause severe complications.
• Erb's Palsy, associated with phrenic nerve damage, can lead to weakness in the affected arm.
• Cephalhematoma, caused by bleeding between the skull bones, typically resolves within a few weeks.
• Asymmetric Moro reflex is indicative of one-sided damage.
• Positive Moro reflex, in full-term newborns, suggests normal development.
• Positive Moro and primitive reflexes are seen in infants with appropriate development.
• Head overlapping of the skull bones is normal for facilitating delivery.
• Respiratory distress is a common cause of mortality in premature infants.
• Abnormal findings in healthy full-term babies, like intra-cranial hemorrhage, are critical.

Thermoregulation

• Treatment for hypothermia includes kangaroo care.
• Normal newborn temperature ranges from 36.5 to 37.5 degrees Celsius.
• Infants lose heat rapidly due to a larger surface area to body mass ratio.
• Axillary and rectal temperatures are used for measurement.
• Moderate hypothermia ranges from 32 to 36 degrees Celsius.
• Management of hypothermia involves radiant warmers, servo-control, and maintaining proper body temperature.
• Hypoglycemia is a common issue in hypothermic infants.
• Infection is a frequent cause of hyperthermia in infants.