Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Chapter 4 Nutrition During Pregnancy Nutrition Through the Life Cycle Judith E. Brown Introduction • Topics covered include: – – – – – – – Status of pregnancy outcome Reducing infant mortality and morbidity Physiology of pregnancy Embryonic & fetal growth and developmen Pregnancy weight gain Nutrition and course/outcome of pregnancy Nutrient needs during pregnancy Introduction • Topics covered include: – Exercise and Pregnancy – Food Safety issues during pregnancy – Common Health Problems during pregnancy • Time-related Terms Before, During, and After Pregnancy The Status of Pregnancy Outcomes • Infant mortality: – Reflects general health status of a population – Decreases in mortality related to improvements in social circumstances, safe & nutritious food supply, & infectious disease control Natality Statistics: Rates, Definitions, and Trends in the Rates in the United States Differences by Race http://www.cdc.gov/nchs/data/databriefs/db09 .htm Chronology of Events Related to Declines in Infant Mortality in the United States Low Birthweight, Preterm Delivery, and Infant Mortality • Low birth weight 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 Reducing Infant Mortality and Morbidity • Improve birth weight of newborns – Desirable birth weight = 3500-4500 g (7 lb. 12 oz.-10 lb.) • Infants born with desirable wt are less likely to develop: • Heart and Lung diseases • Diabetes • Hypertension Health Objectives for 2010 for the Nation Related to Pregnant Women and Infants •The Health Objectives for 2010 in relation to pregnant women and infants focus on •The reduction of low birth weight, •Preterm delivery •Infant mortality •A number of the objectives are related to nutrition Health Objectives for 2010 for the Nation Related to Pregnant Women and Infants •Nutrition related objectives: •Reduce anemia in pregnant females •Reduce incidence of spina bifida •Increase abstinence form alcohol use and reduce the incidence of fetal alcohol syndrome •Increase appropriate weight gain during pregnancy Physiology of Pregnancy • Key terms: – 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 Normal Physiological Changes during Pregnancy – Two phases of changes: – Maternal anabolic changes • Takes place in the 1st half of pregnancy – Maternal catabolic changes • Takes place in the 2nd half of pregnancy Maternal Anabolic and Catabolic Phases of Pregnancy Body Water Changes • Body water • Increases from ~7 L to 10 L – Results from increased blood and body tissues & extracellular volume & amniotic fluid • Edema – Swelling due to accumulation of extracelluar fluid Key Placental Hormones and Examples of their Roles Maternal Nutrient Metabolism • Changes can be seen in the first few weeks after conception. • Ensures that nutrients will be available to the fetus when needed. Carbohydrate Metabolism • Glucose is preferred fuel for fetus • “Diabetogenic effect of pregnancy” results from maternal insulin resistance Carbohydrate Metabolism • Early pregnancy: – High estrogen & progesterone stimulate insulin which increases glucose glycogen & fat • Late pregnancy: – Human chorionic somatotropin (hCS) & prolactin inhibit conversion of glucose to glycogen & fat Protein Metabolism – About 925 g of protein accumulate during pregnancy – Protein & amino acids conserved during pregnancy – No evidence the body stores protein early in pregnancy – Needs must be met by mother’s intake of protein Fat Metabolism • Fat stores – Accumulate in first half of pregnancy – Enhanced fat mobilization in last half • Blood lipid levels increase • Increased cholesterol is substrate for steroid hormone synthesis Mineral Metabolism • Calcium – Increased bone turnover & reformation • Sodium – Accumulation in mother, placenta, & fetus – Restriction of sodium potentially harmful The Placenta • Functions: – Hormone & enzyme production – Nutrient & gas exchange – Remove waste from fetus • Structure: – Double lining of cells separating maternal & fetal blood Structure of the Placenta The Placenta • Nutrient Transfer – Factors that affect the transfer: • Size and charge of molecules • Small molecules pass through most easily – Lipid solubility of particles – Concentration of nutrients in maternal and fetal blood The Placenta • Nutrient Transfer – The fetus is not a parasite – Nutrients first used for maternal needs, then for placenta & last for fetal needed – The fetus is harmed more than the mother by poor maternal nutrition Embryonic and Fetal Growth and Development • Growth and Development – Is at the highest level during the 9 months of gestation – If rate gain continued at this level, at 1 year of age the infant would be 160 lbs. – Table 4.12 provides an overview of embryonic and fetal development 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 • Critical Periods – Preprogrammed time periods during embryonic & fetal development when specific cells, organs & tissues are formed & integrated or functional levels established Critical Periods of Growth and Development • Four periods of growth & development 1) Hyperplasia( cell multiplication) 2) Hyperplasia & hypertrophy 3) Hypertrophy( cell growth) 4) Maturation (stabilization of cell number & size) Fetal Body Composition 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 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) – Ponderal Index (similar to BMI) • Calulated by wt in g divided by cube of lt times 100 • PI for normal wt ~23-25 Nutrition, Miscarriages and Preterm Delivery – Miscarriages • Thought to be caused by genetic, uterine, or hormonal abnormalities – Preterm Delivery – Infants born preterm are at risk for death, neurological problems, congenital malformations, & chronic health problems 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 – Influenced by genes – Also influenced by environmental exposure (in utero) – AKA developmental plasticity • Concept that the development can be modified by particular environmental conditions experienced by a fetus or infant The Fetal-Origins Hypothesis • Environmental Exposures – Modify development – Epigenetic mechanisms • Epigenetics (epi=over, above) – Biological mechanisms that change gene function without changing the structure of DNA. Epigenetic mechanisms are affected by environmental factors. 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 – Unanswered questions • What levels are related to changes? • What exposures? Pregnancy Weight Gain • Weight gain during pregnancy is related to the weight and health status of the newborn infant • Recommendations for weight gain during pregnancy is found in Table 4.17 • Recommendations for weight gain are influenced by the pre-pregnancy status of the mother Pregnancy Weight Gain Recommendations Rate of Pregnancy Weight Gain • ~2-5 pounds in first trimester • Gradual & consistent gains thereafter The Institute of Medicine’s Prenatal Weight-gain Graph Composition of Weight Gain •The fetus is only about 1/3 of the total weight gain •The balance of the weight gain is related to body fat changes, placenta, amniotic fluid, increase of extracellular fluids, and blood supply of the mother 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 Nutrition and the Course and Outcome of Pregnancy • Famine and pregnancy outcome – The Dutch Hungerwinter, 1943-1944 • Decline in pregnancy rates • Lower birth weights – The siege of Leningrad, 1942 • Increase in infertility & low birth weights • Infant death rates increased – Food shortages in Japan • Similar to the outcomes found in Holland and Leningrad above Nutrition and the Course and Outcome of Pregnancy • Contemporary prenatal nutrition research results – “Good nutritional status maintained before and throughout pregnancy decreases the risk of birth defects, suboptimal fetal growth and development, and chronic health problems later in life.” Nutrient Needs During Pregnancy • Nutrient needs vary during the course of the pregnancy • Overall, nutrient needs can be met with well balanced, adequate and healthful diets consisting of basic foods Nutrient Needs During Pregnancy • Energy requirements in pregnancy – ~300 additional cal/d – +340/d in 2nd trimester +452/d in 3rd trimester • Assessment of caloric intake – Most easily assessed by pregnancy weight gain – As long as there is no noticeable edema Carbohydrates, Artificial Sweeteners and Alcohol • Carbohydrate intake (50-65%) • Basic foods such as – vegetables, fruits, and whole grains with fibers = best choice • Artificial sweeteners – No scientific evidence of harm • Alcohol ingestion – Strongly advised to avoid during pregnancy Protein • Protein requirements: – +25 g/day or ~71 g – Average intake of typical female ~78 g The Need for Fat • Pregnant women consume ~33% of total calories from fat • Fat consumed in food is used as an energy source for fetal growth and development • Fat serves as a source of fat-soluble vitamins 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 – Do not exceed 3 grams per day Other Nutrient Needs • The need for water during pregnancy – Met by increased levels of thirst – Average consumption ~9 cups fluid per day – Recommend water, diluted fruit juice, iced tea, and other unsweetened beverages Other Nutrient Needs • Folate and pregnancy outcome – Folate background • Known to be associated with anemia and reduced fetal growth • Folate requirements - extensive organ and tissue growth – Functions of folate • Metabolic reactions • Deficiencies lead to abnormal cell division and tissue formation Other Nutrient Needs • Folate and pregnancy outcome – Folate and congenital abnormalities • NTDs = Neural Tube Defects • Malformations of the spinal cord and brain • Three major types – Spina bifida – Anencephaly – Encephalocele Other Nutrient Needs • Folate and pregnancy outcome – Folate status of women in the United States • Have improved with fortified cereals and supplements – Recommended intake of folate • 600 mcg DFE (dietary folate equivalents) Other Nutrient Needs – Dietary sources of folate • Fruits, vegetables, whole grains A Newborn Child with Spina Bifida Other Nutrient Concerns • Vitamin A – Needed for cell differentiation – In U.S. more concern re: toxicity • Vitamin D – Supports fetal growth – Supports immune system • Fluoride – Teeth begin to develop – Not recommended to supplement Other Nutrient Concerns • Calcium requirements in pregnancy – Needed for fetal skeletal mineralization and maintain maternal bones – Calcium and release of lead from bones • Low intakes of calcium are related to increased release of lead—harmful to fetus – Needs can be met with 3 cups of milk or calcium-fortified soymilk or other adequate sources of calcium. • (See Table 1.14 in Chapter 1) Iron Status and the Course and Outcome of 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 – Early pregnancy-risk of preterm delivery – Late pregnancy-lower scores on intelligence, language, gross motor and attention tests Iron Status and the Course and Outcome of Pregnancy • Assessment of iron status – Iron deficiency: A condition marked by depleted iron stores with weakness, fatigue, short attention span, poor appetite, increased susceptibility to infection and irritability – Iron deficiency anemia: a condition marked by low hemoglobin with signs of iron deficiency plus paleness, exhaustion and rapid heart rate Iron Status and the Course and Outcome of Pregnancy Iron Status and the Course and Outcome of Pregnancy • Pros & Cons of Iron Supplementation – Iron is absorbed better from supplements containing iron only than when mixed with other minerals – Amount absorbed depends on the need and the amount of iron in the supplement – Side effects-nausea, cramps, gas & constipation Iron Status and the Course and Outcome of Pregnancy • Pros & Cons of Iron Supplementation – New concern: free radicals in GI tract->cause inflammation & mitochondrial damage to cells – May interfere with zinc absorption Iron Status and the Course and Outcome of Pregnancy • Recommendations related to iron supplementation in pregnancy – Supplement with 30-mg iron daily after the 12th week of pregnancy • Recommended intake of iron during pregnancy – Upper limit is set at 45 mg per day Other Mineral Concerns • Iodine – Required for thyroid function & energy production and for fetal brain development • Sodium – Restriction not indicated in normal pregnancy or for control of edema or high blood pressure – Plays a critical role in maintaining body’s water balance Bioactive Components of Food – Bioactive food components are foods or dietary supplements other than those needed to meet basic human nutritional needs that are responsible for changes in health status – Are not considered essential nutrients but influence health Caffeine Use in Pregnancy – No apparent long-term consequences for children of coffee intake during pregnancy – Generally concluded-intake of up to 4 cups of coffee per day is safe Healthy Diets for Pregnancy Healthy Diets for Pregnancy • Effect of taste and smell changes during pregnancy on intake – May lead to changes in taste and smell – Pica may result • Pica – Eating disorder: Eat non-food substances Healthy Diets for Pregnancy • Assessment of dietary intake – Cultural considerations • Evaluation of – – – – – Dietary intakes Weight status Biomarkers of nutrient status Vitamin & mineral supplementation Herbal remedies Dietary Supplements During Pregnancy • Multivitamin and Mineral Prenatal Supplements – Nutrient needs should be met by a wellbalanced diet – Iron is considered to be the exception – Recommended for inadequate diets, multifetal pregnancy, smokers, drinkers, vegans, or diagnosed nutrient deficiencies Herbs to Avoid in Pregnancy 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 Food Safety Issues during Pregnancy • Foodborne illness – Listeria monocytogenes – Toxoplasma gondii • Mercury contamination – High levels in large, long-lived predatory fish – Lower content in bottom feeders – Avoid shark, swordfish, king mackerel and tile fish Common Health Problems during Pregnancy • Nausea and vomiting – Hyperemesis gravidarum • Severe N/V during most of pregnancy – Management of nausea and vomiting • Separate liquid & food intake • Avoid odors and foods that trigger N/V – Dietary supplements for the treatment of nausea and vomiting • Vitamin B6, multivitamins, & ginger Common Health Problems during Pregnancy • Heartburn – Management of heartburn • Ingest small meals frequently • Do not go to bed with a full stomach • Avoid foods that make heartburn worse • Constipation – Prevention • Consume dietary fiber • Drink water along with the fiber • Laxative pills are not recommended