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Lesson 2 Preconception and Pregnancy Chapters 2-4. “ Everyone is kneaded out of the same dough but not baked in the same oven.” Yiddish proverb. Preconception Key Nutrition Concept .
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Lesson 2Preconception and PregnancyChapters 2-4 “Everyone is kneaded out of the same dough but not baked in the same oven.” Yiddish proverb
PreconceptionKey Nutrition Concept • Optimal nutritional status prior to pregnancy enhances the likelihood of conception & helps ensure a healthy pregnancy & robust newborn. Key Concept
Nutrition-Related Disruptions in Fertility • Undernutrition • Weight loss • Obesity • High exercise levels • Intake of specific foods & food components
Undernutrition and Fertility • Chronic undernutrition • primary effect: birth of small & frail infants with high likelihood of death in the first year of life • Acute undernutrition • associated with a dramatic decline in fertility that recovers when food intake does
Body Fat and Fertility • Decreased fertility seen with low or high body fat due to alterations in hormones • Estrogen & leptin • levels increased with high body fat & reduced with low body fat • both extremes lower fertility • Infertility lower with BMI <20 or >30
Weight Loss and Fertility in Females • Weight loss >10-15% of usual weight decreases estrogen • Results in amenorrhea, anovulatory cycles, & short or absent luteal phases • Treatment with fertility drug Clomid not effective in underweight women
Diet and Fertility • Diet may impact hormones • Vegetarian diets - low-fat, high fiber linked to reduced estrogen & irregular periods • Isoflavones (from soy) decrease levels of gonadotropins, estrogen, & progesterone • Excess caffeine & alcohol have been shown to be be detrimental
Preconception Iron Status, Fertility, & Pregnancy Outcome • Rate of infertility lower in women who use iron supplements or iron from plant foods • Pre-pregnancy iron deficiency linked to preterm delivery & low iron status of infant • ~1/2 of U.S. women enter pregnancy with inadequate iron stores
Caffeine appears to prolong time to conception Daily caffeine intake & reduction in conception is: 300 mg results in ~27% 500 mg results in ~50% Caffeine and Fertility
Alcohol and Fertility • Alcohol may decrease estrogen & testosterone levels or disrupt menstrual cycles • Studies on weekly drinks consumed show: • 1-5 drinks 39% in conception • >10 drinks 66% in conception
Nutritional Exposures Before and Very Early in Pregnancy that Disrupt Fetal Growth and Development
CDC’s Preconceptional Health Initiative • Recommends that primary health care visits include: • Preconception health & pregnancy outcome education • Screening for vaccination, wt, iron & folate status • Assessment of alcohol use • Management of diabetes & celiac disease
PregnancyKey Nutrition Concept • Many aspects of nutritional status, such as dietary intake, supplement use, and weight change, influence the course and outcome of pregnancy. Key Concept 1
Key Nutrition Concept • The fetus is not a parasite; it depends on the mother’s nutrient intake to meet its nutritional needs. Key Concept 2
Key Nutrition Concept • Critical Periods of rapid growth & development of fetal organs & tissues occur during specific times during pregnancy. Essential nutrients must be available in required amounts during these times for fetal growth & development to proceed optimally. Key Concept 3
Key Nutrition Concept • The risk of heart disease, diabetes, hypertension, and other health problems during adulthood may be influenced by maternal nutrition during pregnancy. Key Concept 4
Key Terms • Gestation – intrauterine fetal growth period from conception to birth (40 weeks). • Embryo- developing organism from conception to 8 weeks gestation. • Fetus – developing organism from 8 weeks gestation until birth.
Stages of Prenatal and Infant Life • Conception- begins when ovum is fertilized with sperm = day 1 • Prenatal period – conception to birth • Perinatal period – 20 wks gestation – 28 day old infant • Neonatal period – birth to 28 day old infant • Postneonatal - 28 day old infant to 1 year old.
Key Terms • Natality statistics: • Status of reproductive outcomes that are assessed through examination of statistical data • Infant mortality • Death that occurs in first year of life • Infant morbidity • Illnesses that occur in first year of life
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
Chronology of Events Related to Declines in Infant Mortality in the United States
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
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
Health Objectives for 2010 for the Nation Related to Pregnant Women and Infants
Maternal Physiology • Changes in maternal body composition & functions occur in specific sequence
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
Summary of Maternal Anabolic & Catabolic Phases of Pregnancy
Components of Increased Oxygen Consumption in Normal Pregnancy
Body Water Changes • Body water • Increases from ~7 L to 10 L • results from increased plasma & extracellular volume & amniotic fluid • Edema • swelling due to accumulation of extracelluar fluid
Maternal Nutrient Metabolism • Pregnancy: A Pro-Oxidative State • Increased oxidation & free radical formation results from: • Increased energy production in mitochondria • Insulin resistance, diabetes, preeclampsia, obesity & infections • Excess iron supplementation
Carbohydrate Metabolism • Glucose is preferred fuel for fetus • “Diabetogenic effect of pregnancy” results from maternal insulin resistance • Early pregnancy: High estrogen & progesterone stimulate insulin which increases glucose glycogen & fat • Late pregnancy: hCS & prolactive inhibit conversion of glucose to glycogen & fat
Plasma Glucose and Insulin Levels in Nonpregnant Women and in Women Near Term
About 925 g of protein accumulate during pregnancy Protein & amino acids conserved during pregnancy Protein Metabolism
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
Mineral Metabolism • Calcium • increased bone turnover • 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
-Maternal arteries & veins are part of the maternal circulation, whereas umbilical arteries & veins are part of the fetal circulation. -Blood enters the fetus through umbilical veins & exits through umbilical arteries. Structure of the Placenta
The Placenta • Nutrient Transfer • Small molecules pass through most easily • Large molecules aren’t transferred at all • The fetus is not a parasite • Nutrients first used for maternal needs, then for placenta & last for fetal needed
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)
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
~2-5 pounds in first trimester Gradual & consistent gains thereafter Rate of Pregnancy Weight Gain