The science of nutrition 4th edition thompson manore vaughan chapter 17

Chapter 17 Lecture

Chapter 17:
Nutrition Through
the Life Cycle:
Pregnancy and
the First Year of
Life

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Nutrition Before Conception
• Adequate nutrition is essential for tissue
formation, neurological development, bone
growth, modeling, and remodeling
• Helps to achieve peak physical and intellectual
potential in adult life

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Nutrition Before Conception (cont.)
• Problems related to nutrient deficiency develop
early
• Neural tube defects:
• Related to inadequate folate status
• Affects the embryo in the first few weeks
• Adequate folate (400 µg daily) before
conception can reduce the risks

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Nutrition Before Conception (cont.)
• Avoid teratogens that cause birth defects:
alcohol and illegal drugs
• Adopt a healthy lifestyle; consult physician about
consumption of caffeine, medications, herbs,
supplements
• Quit smoking

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Nutrition Before Conception (cont.)
• A healthful diet and appropriate levels of
physical activity before conception
• Promote optimal body weight
• BMI 19.8 to 26.0: best chance of
uncomplicated pregnancy and delivery
• Lower risk of negative outcomes such as
prolonged labor, cesarean section,
gestational diabetes, and hypertension

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Nutrition Before Conception (cont.)
• A man's nutrition before conception is also
important

• Sperm number and motility (ability to move) are
reduced by alcohol consumption and certain
prescription and illegal drugs
• Adequate nutrition keeps the immune system
strong and promotes fertility

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Nutrition During Pregnancy
• A balanced, nourishing diet throughout
pregnancy provides the nutrients needed and:
• Supports fetal growth and development
• Provides the mother with the nutrients she
needs
• Minimizes the risks of excess energy intake

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Nutrition During Pregnancy (cont.)
• Full-term pregnancy (gestation) lasts 38 to 42
weeks:
• Three trimesters lasting 13 to 14 weeks each
• Zygote: a single, fertilized cell
• Embryo: weeks 3 to 8 after fertilization
• Fetus: week 9 to birth

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First Trimester
• Zygote travels through the fallopian tube and
implants in the wall of the uterus
• Development of organs, limb buds, facial
features, placenta
• Vulnerable to teratogens during this time
• Spontaneous abortion (miscarriage)
• Placenta provides nutrients via the umbilical
cord

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Second Trimester
• Continued growth and maturation
• Growth from about 3 inches to over a foot long
by the end of the second trimester
• Some babies born prematurely (the end of
second trimester) survive with intensive
neonatal care

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Third Trimester
•
•
•
•
•

Time of intense growth and maturation
Fetus gains ½ to ¾ of its weight
Brain growth is also extensive
Lungs become fully mature
A balanced, adequate diet for the mother
continues to be critical

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Low-Birth-Weight Infants
• Likely among undernourished mothers
• Low birth weight: baby born weighing <5.5 lb
• Increased risk of infections, learning disabilities,
impaired physical development, and death in the
first year of life

• Preterm babies are born before 38 weeks
• Infants that are small for gestational age
(SGA) are full-term but weigh less than expected
for age

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Weight Gain During Pregnancy
• Typically 25−35 lb
• Too much weight gain is also risky
• Pattern of weight gain is important:
• First trimester: 3−5 lb
• Second and third trimesters: average 1 lb per
week
• Weight loss during pregnancy may deprive the
fetus of critical nutrients
• Birth weight of 5.5 lb is a marker of successful
pregnancy
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Nutrition During Pregnancy
• The requirement for nearly all nutrients
increases during pregnancy
• Select foods high in nutrient density
• ChooseMyPlate.gov website is a useful tool
• Pay attention to intakes of:
• Macronutrients (energy)
• Micronutrients
• Fluids

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Macronutrients
• Energy
• Second and third trimesters: add 350−450
calories/day
• Maximize nutrient density
• Safe and physician-approved program of
regular moderate physical activity
• Proteins and carbohydrates
• 1.1 gm/kg body weight/day of protein
• 175 grams/day minimum of carbohydrates

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Macronutrients (cont.)
• Fat

• Same percentage of calories as in nonpregnancy
• Limit saturated fat; avoid trans fats
• Fat helps newborn regulate body temperature
• Omega-3 polyunsaturated fatty acid
docosahexaenoic acid (DHA) is critical for
neurologic and eye development

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Micronutrients
• Micronutrients that are most critical during
pregnancy include:
• Calcium
• Folate
• Iron
• Vitamin B12
• Zinc
• Vitamin C
• Sodium
• Vitamin A
• Iodine
• Vitamin D

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