Download 4 - csulancb12

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