Nutrition During Pregnancy - Chapter 4

Chapter 4 Nutrition during Pregnancy Sofyan Maghaydah Time-related Terms Before, During, and After Pregnancy Low Birthweight, Preterm Delivery, and Infant Mortality Low birthweight (LBW) or preterm infants at high risk of dying in 1st year of life – 8.2% of bir...

Chapter 4 Nutrition during Pregnancy Sofyan Maghaydah Time-related Terms Before, During, and After Pregnancy Low Birthweight, Preterm Delivery, and Infant Mortality Low birthweight (LBW) or preterm infants at high risk of dying in 1st year of life – 8.2% of births are LBW yet comprise 66% of infant deaths – 12.7% are born preterm yet account for high incidence of infant deaths. – The shorter the pregnancy, the less newborns tend to weigh  Reducing Infant Mortality and Morbidity Improve birthweight of newborns – Desirable birthweight = 3500-4500 g (7 lb. 12 oz. to 10 lb.) Infants born with desirable wt less likely to develop: Heart and Lung diseases Diabetes Hypertension  Physiology of Pregnancy Gestational age assessed from date of conception average pregnancy is 38 weeks Menstrual age assessed from onset of last menstrual period average pregnancy is 40 weeks  Maternal Physiology Changes in maternal body composition & functions occur in specific sequence  Maternal Physiology Mother first expands the volume of plasma that can be circulated. Maternal nutrient stores are accumulated next. Stores are established in advance of the time they will be needed to support large gains in fetal weight. Maximal rate of placental growth is timed to precede that of fetal weight gain.  Placenta A disk-shaped organ of nutrient and gas interchange between mother and fetus. At term, the placenta weighs about 15% of the weight of the fetus  Normal Physiological Changes during Pregnancy Two phases of changes: Maternal anabolic changes -Build mother’s capacity to deliver nutrients to fetus -~10% of fetal growth occurs -Weeks 1-20 Maternal catabolic changes -Nutrients delivered to fetus -~90% of fetal growth occurs -Weeks 20-delivery ~40  Body Water Changes Increases from ~7 L to 10 L – results from increased plasma & extracellular volume & amniotic fluid. – Two-third s of the expansion is intracellular (blood and body tissues) – One-third is extracellular ( fluid in spaces between cells). – Begins to increase within few weeks after conception and reaches a maximum at 34 weeks  Body Water Changes Early pregnancy surges in plasma volume responsible for and tiresome Edema – swelling due to accumulation of extracellular fluid. – Healthy plasma volume expansion if not accompanied by hypertension – Strongly related to birth weight. – Dilution effect  Maternal Nutrient Metabolism Pregnancy: A Pro-Oxidative State Increased oxidation & free radical formation results from: – Increased energy production in placental and maternal mitochondria – Insulin resistance, diabetes, preeclampsia, obesity & infections – Excess iron supplementation  Pregnancy: A Pro-Oxidative State Oxidative damage to maternal and fetal cellular structures and functions occur when: – The body’s protective mechanisms are overwhelmed. – External supply of antioxidants is too low Adequate intake of Vitamins C and E Wide variety of naturally occurring antioxidants in vegetables and fruits  Carbohydrate Metabolism Glucose is preferred fuel for fetus “Diabetogenic effect of pregnancy” results from maternal insulin resistance in the third trimester First half : High estrogen & progesterone stimulate insulin which increases glucose glycogen & fat Second half: hCS & prolactive inhibit conversion of glucose to glycogen & fat Insulin resistance builds in the mother, increasing her reliance on fats for energy  Carbohydrate Metabolism Fasting maternal blood glucose levels decline in the third trimester due to increased utilization of glucose by rapidly growing fetus. Postmeal blood glucose concentrations re elevated and remain higher longer than before pregnancy.  Protein Metabolism About 925 g (2 pounds) of protein accumulate during pregnancy Protein & amino acids conserved during pregnancy. Reduced levels of nitrogen excretion. No evidence that mother’s body stores protein early in pregnancy. Maternal and fetal needs for protein are fulfilled by the mother’s intake of protein during pregnancy  Fat Metabolism Fat stores accumulate in first half of pregnancy with enhanced fat mobilization in last half Blood lipid levels increase dramatically Increased cholesterol is substrate for steroid hormone synthesis by the placenta By the fetus for nerve and cell membrane formation Small increase in pregnant HDL declines within a year postpartum heart disease by third trimester most women have lipid profile that is atherogenic.  The Placenta Functions: – Hormone & enzyme production – Nutrient & gas exchange – Remove waste from fetus Structure: – Double lining of cells separating maternal & fetal blood  The Placenta Role of placenta is a fence rather than a filter. Potentially harmful substances do pass Alcohol, high vitamins, drugs, and certain viruses. Barrier to passage of maternal RBC, bacteria, and many large proteins  Nutrient Transfer Placenta uses 30-40% of the glucose delivered to the fetus. If nutrient supply is low, placenta fulfills its needs first. If nutrient supply falls short, functioning of the placenta is compromised Factors for nutrient transfer – the size and the charge of molecules. – Lipid solubility of particles – Concentration of nutrients in maternal and fetal blood The fetus is not a parasite – Nutrients first used for maternal needs, then for placenta & last for fetal needed. – Underweight women gaining the same amount of weight as normal-weight women tend to deliver smaller infants. – Fetal growth tends to be reduced in pregnant teenagers who gain height during pregnancy.  Critical Periods of Growth and Development Differentiation – Cellular acquisition of one or more characteristics or functions different from that of the original cell during set time intervals. Critical Periods – Preprogrammed time periods during embryonic & fetal development when specific cells, organs & tissues are formed & integrated or functional levels established – Most intense during the first 2 months after conception  Critical Periods of Growth and Development Four periods of growth & development 1) Hyperplasia( cell multiplication) 2) Hyperplasia & hypetrophy 3) Hypertrophy( cell growth) 4) Maturation (stabilization of cell number & size)  Variation in Fetal Growth Variations linked to: – Energy, nutrient, & oxygen availability – Genetically programmed growth & development Insulin-like growth factor (IGF-1) is main fetal growth stimulator  Variation in Fetal Growth Levels of IGF-1 is sensitive to maternal nutrition and its decreased by under nutrition Factors: – Pregnancy underweight and shortness – Low eight gain during pregnancy – Poor dietary intake – smoking, drug abuse Newborn Weight Classifications Terms to describe newborn size SGA (small for gestational age) dSGA (disproportionately small for gestational age) pSGA (proportionately small for gestational age) LGA (large for gestational age)  SGA (small for gestational age) Newborn weight is less than the 10th percentile for the gestational age. Further categorized into dSGA pSGA dSGA (disproportionately small for gestational age) Newborn weight is less than the 10th percentile of weight for gestational age. Normal length and head circumference They look skinny and wasted Small abdominal circumference..lack of glycogen in liver and body fat Short term episodes of malnutrition, weight loss or low weight gain late in pregnancy.  dSGA (disproportionately small for gestational age) Smaller organ size At risk of developing the hypos afterbirth Hypoglycemia Hypocalcemia Hypomagnesmia Hypothermia – If the period of maternal under nutrition is short. dSGA tend to have a chance to catch-up – Perform less well academically – CHD, BP, DM 2  pSGA (proportionately small for gestational age) Newborn weight, length, and head circumference are less than 10th percentile for gestational age. Experienced long term malnutrition Reduced number of cells in organs and tissues. Catch-up growth is poor Short, light and smaller head circumference  LGA (large for gestational age) Weight for gestational age exceeds the 90th percentile for gestational age. Birth weight greater than 4500g. Pregnancy obesity, poorly controlled DM. Excessive weight gain during pregnancy Shoulder dystocia  Preterm Delivery Infants born preterm are at risk for death, neurological problems, congenital malformations, low IQ scores & chronic health problems such as cerebral palsy. A group of disorders characterized by impaired muscle activity and coordination present at birth Very preterm have problems related to growth, digestion. Respiration due to immaturity  Fetal-Origins Hypothesis of Later Disease Risk Theory that exposures to adverse nutritional & other conditions during critical or sensitive periods of growth & development can permanently affect body structures & functions Changes may predispose individuals to CVD, type 2 diabetes, hypertension & other disorders in later life The Fetal-Origins Hypothesis Mechanisms underlying the fetal origins hypothesis Nutrition programming -Fetal exposure to certain levels of energy & nutrients modify function of genes in ways that affect metabolism & development of diseases in later life Limitations of the fetal-origins hypothesis Pregnancy Weight Gain Recommendations Composition of Weight Gain Postpartum Weight Retention Much concern over pregnancy weight gain and long-term obesity – ~15 pounds lost at delivery – Wt loss difficult in women who gained >45 pounds or with low activity levels – Women with recommended wt gain in pregnancy are ~2 pounds heavier at 1 yr postpartum – Lactating women lose slightly more  Energy requirements in pregnancy ~300 additional cal/d (+340/d in 2nd trimester +452/d in 3rd trimester) Total of 80,000 Kcal Assessment of caloric intake by body weight  Carbohydrate Intake During Pregnancy Carbohydrate intake (50-65%) About 175g is recommended to meet the feta brain’s need for glucose High fiber foods are recommended for phytochemicals and against constipation Glycemic index (GI) of carbohydrates – High-GI foods increase fetal fat  Artificial Sweeteners – No scientific evidence of harm Aspartame Acesulfame K  Alcohol Ingestion – Strongly advised to avoid during pregnancy – Passes through the placenta and interrupts normal growth and development – Strongly related to abnormal mental development and growth in the offspring. – Fetal alcohol syndrome  Protein +25 g/day ~71 g for females aged 14 and older Average intake of typical female ~78 g Maternal Intake of Omega-3 Fatty Acids and Pregnancy Outcome Adequate EPA & DHA during pregnancy & lactation linked to higher intelligence, better vision & more mature CNS Dietary intake recommendations for EPA & DHA AI = 300 mg UL = 2 g  Vitamin A and pregnancy outcome Cell differentiation Malformation of fetal lungs, urinary tract and heart Excessive retonic acid (not beta-carotene)10,000IU/day Acucutane and Retina-A for acne and wrinkle Fetal abnormalities Retonic acid syndrome Small ears, no ears brain malformation, hearts defects 50,000IU as retonol  Vitamin D requirements Poor fetal bone formation Poor calcium utilization Small, poorly calcified bones and enamel. Low levels of blood calcium after birth 5 mcg (200IU) 3 cups of Vit.D -fortified milk 2 sunbaths (15 min/week 1250mcg Dark skin needs 5 sunbaths Food and supplements Vit. Not exceed 50mcg /day Calcium requirements in Pregnancy – Calcium absorption increases – 300mg late pregnancy – Deficincy: – Blood pressure during pregnancy and fetal – Decreased bone remineralization – Release of lead from bones to blood during bone demineralization  Iron During Pregnancy Additional iron needs for pregnancy – 300 mg for fetus & placenta – 250 mg lost at delivery – 450 mg for increased RBC Iron-deficiency anemia in pregnancy – Seen in ~18% of pregnant women in developed countries – LBW, preterm delivery – Low scores on intelligence, language, gross motor, and attention tests.  Zinc requirements in pregnancy Protein synthesis High bioavailability high in meat Low in plant foods..cereal Iron (30 mg) and Zinc Reliance on whole grains preterm delivery Hemorrhage Infections Prolonged labor Antioxidants from plants – Antioxidants help protect fetal DNA – Maternal vitamin E intake reduces risk of asthma in children  Iodine and pregnancy Synthesis of thyroid hormones and protein tissues Early in pregnancy Hypothyroidism Growth impairment, mental retardation And deafness Fish, shellfish, and seaweed Sodium during Pregnancy – Restriction not indicated in normal pregnancy or for control of edema or high blood pressure Caffeine Use in Pregnancy No apparent long-term consequences for children of coffee intake during pregnancy High levels of coffee/caffeine intake (over 500 mg/day) related to miscarriage  Exercise and Pregnancy Outcome No evidence that moderate or vigorous exercise undertaken by healthy women is harmful Exercise recommendation for pregnant women – 3-5 times each week for 30 minutes at 60-70% VO2 max  Common Health Problems during Pregnancy Nausea and vomiting – Hyperemesis gravidarum – Management of nausea and vomiting – Dietary supplements for the treatment of nausea and vomiting Vitamin B6, multivitamins, & ginger Heartburn – Management of heartburn Constipation