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Chapter 15
Pregnancy & Lactation
Prior To Pregnancy
• Goals-essential to conception & healthy infant development– Achieve and maintain a healthy
body weight– Choose an adequate and balanced
diet– Be physically active– Avoid harmful influences
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Fetal Growth & Development• Ovum + sperm zygote
• Zygote – the first 2weeks after fertilization– Implantation
• Embryo – 2 to 8 weeks after conception
• Fetus – from 8 weeks after conception to full-term
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Critical Periods-if cell division and number are limited during a critical period full recovery is not possible
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Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Critical Periods• Neural tube defects
– Anencephaly-the neural tube fails to close so the brain is either missing or fails to develop
– Spina bifida-incomplete closure of the spinal cord and its bony encasement
• Folate supplementation reduces the risk
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Weight Prior To Conception• Increased medical risks if a woman is
under- or overweight prior to pregnancy• Prepregnancy weight affects development
of healthy support tissues – placenta, amniotic sac, etc.
• Prepregnancy weight affects infant birthweight – Infant birthweight is the most potent
predictor of infant’s future health & survival
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Weight Prior To Conception
• Underweight– Preterm
• Overweight and obesity– Post term– Cesarean section– Dieting is dangerous because ketosis
from fasting/low-CHO diets impairs fetal brain development
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Weight Gain
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Weight Gain
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Weight Gain
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Nutrient NeedsEnergy – Extra food energy needed
1. No additional allowance is provided during the 1st trimester 2. During the 2nd & 3rd trimesters RDA + 350-450 kcals/day 3. More if teenager, underweight, very active, or multiple gestationProtein – RDA +25 grams/day (~70 gms); usually not a problem since most diets already exceed recommendation
Nutrient NeedsVitamins – Folate & Vitamin B12 needed in
large amounts for rapid cell proliferationFolate needed for increased red blood cells and to help prevent neural tube defects
1. Recommendation increases from 400 micrograms/day during childbearing years to 600 micrograms/day during pregnancy usually from supplementsVitamin B-12 – RDA during pregnancy is 2.6 mcg/day; supplements recommended for vegans
Nutrient Needs• Minerals needed for:
1. Bones & teeth – calcium, phosphorous, magnesium & fluoridefluoride involved in involved in
building the skeletonbuilding the skeleton2. Blood – iron necessary for 50%
increase in maternal blood volume and accumulation of fetal iron stores during the 3rd trimester
3. Protein synthesis- zinc vital for DNA & RNA synthesis
Nutrient Needs
Calcium – 1200 mg/day recommended to conserve maternal bone mass while
supplying fetal needsFlouride – supplements not recommended
if water flouridatedIron – increased need cannot be met by diet
or existing stores so supplements (30 mg/day) recommended during 2nd & 3rd trimesters
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High-Risk Pregnancies
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High-Risk Pregnancies
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Food Assistance Programs
WIC Program – helps low income pregnant women & their children (<5 years) obtain needed food and nutrition education for growth & development and to reduce the risks of preterm or low-birth weight infants
Maternal HealthPreexisting Diabetes or Gestational Diabetes –
high blood glucose can lead to fetal (macrosomia) & delivery complications
1. Usually dx’d in 2nd or 3rd trimester by glucose tolerance test; screening at 24-28 weeks gestation 2. Dietary control involves avoiding simple sugars, eating small, frequent meals/snacks, and preventing excessive weight gain 3. 1/3 of women will go on to develop diabetes in future
Maternal Health
Preexisting Hypertension or Preeclampsia– high blood pressure may be preexisting condition or may be pregnancy-induced signaling onset of preeclampsia (condition
characterized by high blood pressure, generalized edema, & proteinuria) 1. Control involves good nutrition (esp. calcium) & bedrest
Nutrition-Related Concerns• Nausea• Constipation and hemorrhoids• Heartburn• Food cravings and aversions- due to
hormone-induced changes in sensitivity to taste and smell instead of reflecting true physiological needs
• Nonfood cravings – laundry starch, clay, soil, ice– Pica is associated with iron deficiency
anemia
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Maternal DiscomfortsNausea/Morning Sickness – caused by
hormonal changes early in pregnancy (increased levels of hCG)
• Ways to Alleviate1. On waking, rise slowly2. Eat dry toast or crackers in morning3. Eat small, frequent low-fat meals 4. Avoid strong or offensive food odors
• Severe cases – hyperemsis gravidarum; usually require rehydration & hospitalization
Maternal DiscomfortsHeartburn – as baby grows, pressure on
mother’s stomach increases causing reflux• Ways to Alleviate
1. Eat small, frequent meals slowly2. Drink liquids between meals3. Avoid spicy or greasy foods 4. Avoid lying down for right after eating
and elevate the head while sleeping
Maternal DiscomfortsConstipation – slower GI motility• Ways to Alleviate
1. Increase fluid intake to8 glasses a day2. Eat foods high in fiber (fruits,
vegetables, whole-grain cereals) 3. Exercise regularly
4 Use laxatives only as prescribed by a physician; do not use mineral oil because it interferes with the absorption of fat-soluble vitamins
Practices Incompatible with Pregnancy
1. Cigarette smoking – restricts blood supply to fetus, impairing fetal nutrition & increases risk of low birth weight and SIDS infants
2. Caffeine – limit to 1 cup “coffee”/day or may lower infant birthweight
3. Medicinal Drugs – prescription meds only with M.D. approval due to risk of birth defects
Practices Incompatible with Pregnancy
4. Illicit drugs, such as cocaine or marijuana, also pass through placenta
causing toxicity & central nervous system damage
5. Herbal supplements6. Vitamin/mineral megadoses are toxic7. Sugar substitutes in moderation8. Alcohol may cause fetal alcohol
syndrome (severe mental & physical retardation) & interferes with transport of nutrients across placenta
Fetal Alcohol Syndrome
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Lactation• Mammary glands- secrete milk• Prolactin – hormone responsible for milk production• Oxytocin-hormone that causes milk to eject• Let-down reflex
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Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Mother’s Nutrient Needs During Lactation
• Energy Needs – additional 500 kcals/day needed to produce
~25 oz. milk/day provided by food & fat reserves (stored energy)
1. Breastfeeding can facilitate maternal weight loss
2. Avoid diets - <1200 kcals/day compromises milk production
Mother’s Nutrient Needs During Lactation
• Fluids - >2 qts./day to prevent dehydration
• Prenatal vitamin supplements routinely prescribed
- RDAs same or slightly higher for most nutrients except iron until menstruation resumes
Mother’s Nutrient Needs During Lactation
• Recommendation for protein the same as during pregnancy
• Vitamins & Minerals – supplements generally recommended to replete maternal stores; prolonged inadequate intakes reduce the quality of the milk
• Water – 3 L/day to prevent dehydration
Lactation• Certain foods, esp. with strong or spicy
flavors, are avoided only if baby seems sensitive
• Caffeine may cause irritability & difficulty sleeping• Alcohol easily enters breast milk• Smoking decreases milk production• Medicinal Drugs – most are compatible but
need to check with physician for those contraindicated
• Illicit Drugs – high doses delivered in breast milk
Lactation
• Breastfeeding considered the “gold standard” for infant feeding due to immunologic, health & social benefits
• Contraindications – Communicable diseases (TB, hepatitis, HIV, etc.) and certain meds/drugs that
adversely affect infant
Energy & Nutrient Needs
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Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Nutrient Needs