CHAPTER 16 PREG AND BF NUTRITION HUMAN NUTRITION

1. Because learning changes everything.®
Chapter 16
Pregnancy and Lactation
Lecture Outline
HUMAN NUTRITION
Science for Healthy Living
Third Edition
Tammy J. Stephenson, Megan R.
Sanctuary, Caroline W. Passerrello
© 2022 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom.
No reproduction or further distribution permitted without the prior written consent of McGraw Hill, LLC.

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16.1 Preparing for Pregnancy: Nutrition Concerns
Learning Outcomes
1. Define the preconception period and explain why
following a healthy lifestyle and receiving proper health
care are important during this period.
2. Discuss the importance of the preconception diet for
optimizing fertility and pregnancy outcomes.
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Preparing for Pregnancy 1
A woman entering pregnancy (gestation) in the best physical
condition and with adequate nutrient stores in her body is
likely to achieve two major positive outcomes:
• A healthy newborn
• Healthy new mother
Positive lifestyle choices are also important for the father-to-
be, as healthy choices may affect the quality of his sperm
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Preparing for Pregnancy 2
When planning for pregnancy, both women and men should
consider adopting healthy lifestyles that include:
• Consuming a nutritionally optimal diet
• Having a healthy body mass index (BMI) and body
composition
• Avoiding harmful substances, including alcohol, tobacco,
and other environmental toxins
• Exercising regularly
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The Preconception Period
The preconception period is the 3-month time before
pregnancy
• Much important development occurs very early in
pregnancy
• For example, the heartbeat of the growing baby is detectable as
early as the sixth week of gestation
• Many women are unaware that they are pregnant until 6 to
8 weeks of gestation
• Having adequate nutrient stores in the body before pregnancy
begins is crucial
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Preconception Health Counseling1
According to the CDC, couples can benefit from
preconception health counseling before they begin efforts to
conceive
• The healthcare provider discusses aspects of diet and
lifestyle that can reduce the risk of having negative
pregnancy outcomes, for example:
• Having a baby that is born too soon
• Having an infant with birth abnormalities, such as neural tube
defects (NTDs)
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Preconception Health Counseling2
Other possible counseling topics include:
• Stabilize or improve the hath of women who have chronic
medical conditions, such as diabetes or hypertension
• Counseling to avoid exposure to a variety of
environmental toxins, including pesticides, nicotine,
marijuana, anabolic steroids, and cocaine
• Exposure to these substances can damage sperm’s genetic
material (DNA) and reduce male fertility
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Nutritional Considerations in Fertility1
Fertility is the capability to reproduce
• For women, it is the ability to become pregnant
• For men, to produce healthy, viable sperm
In the U.S., the total fertility rate (TFR), the number of
expected births per 1,000 women, was 16% below the level
needed to replace the current population in 2017
• A TFR greater than 2,100 is necessary to replenish a
population over time
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Total Fertility Rates for the United States
As of 2017, only two states had TFRs over the level needed
to replace the population over time
SOURCE: NCHS, National Vital Statistics System, Natality.
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Contributing Factors to the Declining TFR
Contributing factors to the declining TFR include:
• Access to birth control
• Higher education and professional careers of women
• Increased childcare expenses
• Infertility - the failure to conceive after 12 months of trying
to become pregnant
• About 15% of couples experience infertility
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Causes of Infertility
Some causes of infertility are inherited or physiological
Recent evidence suggests that certain nutrients and overall
dietary patterns promote fertility
• Obesity and associated hormonal imbalances can
contribute to infertility, for example:
• Polycystic ovarian syndrome (PCOS)
• Diabetes
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Nutritional Considerations in Fertility2
The macronutrient composition of the diet likely plays a role
in fertility as it affects blood insulin levels
Several micronutrients are also relevant to fertility
• Adequate status of folate, iron, and vitamin D are
important in female egg production
Alcohol and caffeine have also been associated with reduced
fertility in women
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Nutritional Considerations in Fertility3
The Nurses’ Health Study II ranked women based on their
intake of different foods and nutrients
• The women with the lowest rates of infertility had diets
characterized by:
• High intake of vegetables, full-fat dairy foods, iron, monounsaturated
fats, and use of multivitamins
• Lower intakes of animal protein, high glycemic load foods, and low-
fat dairy
Few studies have addressed the role of diet in male fertility
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Did You Know? – Fertility Foods in Indigenous Cultures
In indigenous cultures where people consume ancestral
traditional diets, the importance of the preconception diet is
well known
• Special foods are often reserved for women who plan to
become pregnant, women who are pregnant or nursing,
small children, and potential fathers
• In certain native cultures of Alaska, salmon eggs (fish roe)
are dried and saved as fertility foods for women
• In some native Peruvian cultures, egg yolks and organ
meats are eaten as fertility foods
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Assess Your Progress 16.1
1. Why is it important for a woman to eat a nutritious diet
prior to pregnancy?
2. Describe the total fertility rate (TFR). What is the TFR in
the United States?
3. Describe the role of diet in fertility. List two foods that
should be avoided and three foods that should be
consumed to promote fertility.
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16.2 Physiology of Pregnancy
Learning Outcomes
1. Summarize the major physiological milestones that occur
during each of the three trimesters of pregnancy.
2. Discuss how the placenta develops and the major
functions of this organ.
3. Identify the major physiological adjustments that occur in
a woman's body during pregnancy.
4. Describe the contribution of various tissues to weight gain
during pregnancy.
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Pregnancy Terms
Conception (fertilization)- the point at which a women’s egg
(ovum) is fertilized by a sperm and pregnancy begins
Prenatal period - the time from conception until birth
• Full term describes a baby born after 38 weeks of
gestation
• Preterm describes a baby born before week 38 of
gestation
• The prenatal period is often divided into trimesters, that is
three-month (or about 13-week) periods during pregnancy
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The First Trimester1
Conception begins with ovulation, the release of an ovum
(egg) from an ovary
If sperm are present in the fallopian tube and one of them
fertilizes the egg, a zygote is formed and pregnancy begins
• During the first few days, the zygote divides repeatedly in
the fallopian tube, forming a mass of cells (blastocyst)
• It enters the cavity of the uterus, the female reproductive organ that
houses the fetus before birth
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The First Trimester2
In the process of implantation, the blastocyst imbeds itself in
the uterine lining
• Receives nourishment from nutrients that are stored in the
lining of the uterus
• The nutritional status of the mother prior to conception is very
important
• The zygote and blastocyst form during the pre-embryonic
stage of development
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Conception and Implantation
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The First Trimester3
• Embryo refers to the offspring from 2 to 8 weeks after
conception
• Fetus refers to the offspring from 8 weeks until birth
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The Placenta and Umbilical Cord
• Placenta - organ that
forms on the lining of the
uterus and functions to
deliver nutrients and
oxygen to the fetus and
remove wastes
• Umbilical cord -
structure that extends
from the fetus to the
placenta
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The Placenta1
The transport of nutrients and respiratory gases between
maternal (the mother’s) blood and blood of the developing
offspring occurs by diffusion
All nutrients are necessary for a healthy pregnancy outcome
• Those involved in cell production are extremely important
during the first trimester
• This stage of development is a critical period because organs form
quickly during this time
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The Placenta2
The placenta acts as a barrier, preventing potentially harmful
substances in the maternal bloodstream from being
transferred to the developing offspring
• Does not prevent transfer of various teratogens,
environmental substances that cause abnormalities (birth
defects) or miscarriage
• Teratogens include: many drugs (for example alcohol and nicotine),
viruses, excess vitamin A
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Second Trimester
• As the second trimester begins, the fetus is about 3 ½
inches in length and 1 ½ ounces in weight
• By 5 months of gestation, the fetus is about 7 ½ inches in
length and weighs about 1 pound
• In this trimester, the organs continue to grow and mature
in their ability to function
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Third Trimester
Most fetal weight gain occurs during the third trimester
• At the start of this trimester, the fetus is under 2 pounds
and about 9 inches long (from crown to rump)
The rate of weight gain is:
• ½ oz/day during 7th month
• 1 oz/day during the last 2 months
A full-term infant is generally 7 to 8 pounds and about 20
inches in length
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Common Signs and Symptoms of Pregnancy 1
Common signs and symptoms of pregnancy include:
• Breast changes
• Nausea and vomiting
• Morning sickness is nausea and/or vomiting during pregnancy
• Hyperemesis gravidarum is a severe form of nausea and vomiting
that can occur during pregnancy
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Common Signs and Symptoms of Pregnancy 2
Common signs and symptoms of pregnancy also include:
• Fatigue and sleepiness
• Frequent urination
• Food cravings and aversions
• Food craving – urge to consume a particular food or a combination
of foods
• Food aversion - intense dislike of a food that was previously
enjoyed
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Physiological Changes During Pregnancy
Hormonal Change Effects on Maternal Physiology
Increased synthesis and secretion
of the hormones estrogen and
progesterone
Facilitates uterine and breast enlargement and
suppresses ovulation
Slows gastrointestinal tract movements, which
enhances nutrient digestion and absorption but
can lead to constipation (progesterone)
Synthesis and secretion of the
hormone human placental
lactogen
Increases metabolic rate
Increased synthesis and secretion
of the hormone prolactin
Stimulates cells in the breast (mammary gland
cells) to prepare for milk production
Increased blood levels of the
hormone aldosterone
Increases blood volume, which may increase
blood pressure during the first trimester
Lowers concentration of red blood cells in
bloodstream
Increases likelihood of edema late in pregnancy
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Fresh Tips – Dietary Strategies to Control Morning
Sickness
Dietary strategies that are often recommended to control
morning sickness include:
• Eating small, frequent meals every 2 to 3 hours.
• Drinking ginger tea or nibbling on dried ginger pieces.
• Choosing healthy snacks, including those that are high in
protein, such as nuts or yogurt.
• Supplementing with low doses of vitamin B-6.
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Changes to Maternal Tissues During Pregnancy
During pregnancy, many tissues in a woman’s body change
and grow, including expansion of:
• Blood volume
• Breast and fat tissue
• The uterus
In addition to this growth, women also gain weight during
pregnancy from the developing placenta and fetus
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Position of Full-Term Fetus
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Distribution of Weight Gain During Pregnancy
Tissue or Component
Approximate
Pounds
Maternal: Blood 4
Maternal: Breasts 2
Maternal: Uterus 2
Maternal: Fat 7
Maternal: Retained fluid 4
Fetus 7.5
Placenta 1.5
Amniotic fluid (fluid surrounding embryo/
fetus)
2.0
TOTAL 30.0
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Maternal Weight Gain1
Gaining an appropriate amount of weight is important for a
healthy pregnancy:
• Both inadequate and excessive maternal weight gain
result in an increased risk of complications and poor
pregnancy outcomes
The total amount of weight gained by the end of pregnancy
depends on the pre pregnancy weight of the woman
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Recommendations for Total Weight Gain During
Pregnancy
The American College of Obstetricians and Gynecologists
(ACOG) recommends that women whose pre pregnancy
weight was in the normal range should gain 25 to 35 pounds
Recommended Weight Gain (Pounds)
Pre pregnancy Weight
Classification
For Single Birth For Twin Birth
Underweight 28 to 40 Not established
Normal weight 25 to 35 37 to 54
Overweight 15 to 25 31 to 50
Obese 11 to 20 25 to 42
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Maternal Weight Gain2
Women who gain too much weight during pregnancy:
• Often have difficulty losing the weight after delivery
• Have a greater chance of developing complications
Mothers should be careful not to be overly concerned with
weight gain during pregnancy
• Calorie restriction and excessive exercise can be harmful
to both the mother and the fetus
Women who experience inadequate weight gain may have a
small or poorly developed placenta
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Rate of Weight Gain
The rate of weight gain during pregnancy is as important as
the total amount gained
• During the first trimester, healthy women usually gain only
1 to 5 pounds
• Recommendations for the rate of weight gain during the
second and third trimesters are based on the
prepregnancy weight and BMI of the woman
• Regardless of prepregnancy weight, women should gain about 1.0
to 4.5 pounds during the first trimester
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Recommendations for Weight Gain by Trimester of
Singleton Pregnancy
Prepregnancy
Weight Classification
Total Weight Gain (Pounds)
First Trimester
Weight Gain
(Pounds/Week)
Second and Third
Trimesters
Underweight 1.0 to 4.5 pounds 1
Healthy weight 1.0 to 4.5 pounds 1
Overweight 1.0 to 4.5 pounds 0.6
Obese 1.0 to 4.5 pounds 0.5
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Gastrointestinal Disturbances During Pregnancy 1
Hormonal changes combined with increasing pressure on
the intestinal tract by the growing uterus often contribute to
constipation
• Prenatal supplements, especially those with high amounts
of iron, may also cause constipation
To help prevent constipation, women should:
• Consume adequate fiber, supplement with probiotics or
eat fermented foods, drink fluids
• Exercise regularly throughout pregnancy
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Gastrointestinal Disturbances During Pregnancy 2
Heartburn is another common complaint caused by hormonal
changes and increased abdominal pressure
• As the fetus grows, the uterus pushes upward, putting
increased pressure on the stomach
• Stomach acid can enter the esophagus, causing heartburn
• Women can reduce heartburn symptoms by eating small
meals and resting in an upright position
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Assess Your Progress 16.2
4. Compare and contrast the trimesters of pregnancy in
terms of embryonic and fetal development.
5. Why is the health of the placenta so important during
pregnancy?
6. List the major physiological changes that women are
likely to experience during pregnancy.
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16.3 Nutrition and Lifestyle for a Healthy Pregnancy and
Delivery
Learning Outcomes
1. Discuss the importance of adequate energy and nutrient
intakes during pregnancy.
2. Describe the concept of developmental origins of disease.
3. Explain why women should be sure to get enough safe
physical activity during pregnancy.
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Nutrition for a Healthy Pregnancy
Increased nutrient needs, food cravings and
aversions, along with decreased room for
stomach expansion make the selection of
highly nutritious foods very important during
pregnancy
• According to the 2020 to 2025 Dietary
Guidelines for Americans, folate, iron,
iodine, and choline are nutrients of
concern for women who are pregnant
or lactating
• Women who have well-balanced diets
before becoming pregnant need to make
few dietary changes during pregnancy
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Energy Needs
During the first trimester of pregnancy, a woman’s daily
energy requirement is essentially the same as before
pregnancy
During the second and third trimesters, women require
additional energy to support the growth of:
• Their enlarging placenta
• Breast tissue
• Fetus
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Comparison of Selected Energy and Macronutrient DRIs:
25-Year-Old Nonpregnant and Pregnant Women
Energy or Nutrient Nonpregnant Pregnant
Kilocalories Estimated
Energy
Requirement
(EER)
First Trimester: EER + 0 kcal
Second Trimester: EER + 340 kcal
Third Trimester: EER + 452 kcal
Carbohydrate 130 g 175 g
Fiber 25 g 28 g
Linoleic acid 12 g 13 g
Alpha-linolenic
acid
1.1 g 1.4 g
Protein 46 g 71 g
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Protein Needs
The RDA for protein during pregnancy is 71 g protein/day
• Women who consume plant-based diets that include dairy
and eggs appear to have ample protein intakes
• It may be difficult for women following a vegan diet to
consume the RDA for protein
• They should be sure to practice protein complementation and track
their protein intake
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Essential Fatty Acid Needs
During pregnancy, the DRI for the essential fatty acids
increase as follows:
• For alpha-linolenic acid, from 1.1 to 1.4 g/day
• For linoleic acid, from 12 to 13 g/day
Adequate intake of eicosapentaenoic acid (EPA) and
docosahexaenoic (DHA) is necessary for proper fetal brain
and retina development
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Vitamins and Mineral Needs
Women require greater amounts of several vitamins and
minerals during pregnancy
• Consuming an adequate diet based on whole foods is the
best way to ensure optimal micronutrient intake
• Nonetheless, women are encouraged to take a daily prenatal
vitamin throughout pregnancy to fill in any gaps in the diet
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Comparing Recommended Intakes and ULs of Selected Vitamins
and Minerals: 25-Year-Old Nonpregnant and Pregnant Woman
Nutrient
Nonpregnant
RDA
Pregnant
RDA
ULs are the same for
Nonpregnant and
Pregnant Women
Vitamin A 700 μg 770 μg 3,000 μg
Folate (DFE) 400 μg 600 μg 1,000 μg
Vitamin B-12 2.4 μg 2.6 μg No UL
Vitamin C 75 mg 85 mg 2,000 mg
Vitamin D 15 μg (600 IU) 15 μg (600 IU) 100 μg (4,000 IU)
Calcium 1,000 mg 1,000 mg 2,500 mg
Iron 18 mg 27 mg 45 mg
Iodine 150 μg 220 μg 1,100 μg
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Vitamin D
Vitamin D deficiency is widespread among women in the
U.S. and throughout the world
• The RDA for vitamin D during pregnancy is 15 μg/day
• Pregnant women are encouraged to get plenty of sunlight
exposure
• According to some experts, pregnant women can safely
consume 100 μg/day, which is the UL
• More research is necessary to recommend this level of intake
during pregnancy
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Folate
Adequate levels of folate are essential for proper
development of the neural tube
• A structure that becomes the brain and spinal cord and
forms prior to the fourth week of gestation
Low intake of folate during the preconception period can lead
to neural tube defects (NTDs)
• NTDs, including spina bifida and anencephaly, are
developmental abnormalities of the brain and spinal cord
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Folate and Neural Tube Defects (NTDs)
NTDs can result in:
• Paralysis of the lower limbs
• Problems with intestine and
bladder function
• Blindness
• Deafness
• Learning disabilities
• Death
Adequate intake of folate, such as
from green leafy vegetables, can
help prevent NTDs
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Vitamin A
Vitamin A plays a vital role in the formation of the heart, eyes,
circulatory system, urogenital system, and respiratory system
• Deficiency during pregnancy can lead to congenital
malformations in these tissues
It is important for pregnant women to consume:
• Preformed vitamin A in dairy products, butter, liver
• Beta-carotene found in many orange vegetables, such as
carrots and sweet potatoes
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Iron
The RDA for iron increases from 18 mg for women to 27 mg
during pregnancy
Additional iron is needed to:
• Support increased maternal hemoglobin synthesis
• Transfer iron to the developing offspring for production of
its own hemoglobin
Iron sources include:
• Beef, fish, and poultry
• Vegetables and grains
• Dietary supplements
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Iodine
The RDA for iodine increases from 150 μg for women to 220
μg during pregnancy
• The body needs iodine to synthesize thyroid hormone,
which is critical for normal fetal brain development
• Children born to mothers who had severe iodine deficiency during
pregnancy are at risk of cretinism
• Women who avoid using iodized salt during pregnancy
should ask their healthcare provider about the need to
take a prenatal supplement with the recommended
amount of iodine
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Calcium
The RDA for calcium does not increase during pregnancy, as
absorption in the GI tract increases
• Many women, however, do not consume enough calcium-
rich foods
• In the third trimester, fetal bone mineralization occurs at a rapid rate
• It is important for women to enter pregnancy with ample
calcium reserves
• Food sources include:
• Dairy products
• Green leafy vegetables such as cooked kale and broccoli
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Did You Know? – Pica: Nonfood Cravings
Some people, especially pregnant women, crave and eat
nonfood items, such as dirt, clay, or laundry starch, on a
regular basis
• This practice is called pica
• It is unclear whether this practice causes iron deficiency or
is the result of the deficiency
• The components of dirt, clay, or raw starch may include
the toxic mineral lead that binds to trace minerals such as
iron, or may compete with mineral absorption
• Certain bacterial infections or worm infestations may result
from eating contaminated soil
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Developmental Origins of Disease
Developmental origins of health and disease (DOHaD) -
the concept that the nutritional environment during fetal
development affects disease susceptibility later in life
• Some chronic diseases may partly be due to a mismatch
between the nutritional conditions that a fetus is exposed
to during gestation and the nutritional environment in later
stages of life
• Including cardiovascular disease (CVD), diabetes, metabolic
syndrome, and cancer
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Maladaptive Fetal Programming1
During the Dutch winter famine, babies who experienced
starvation conditions during gestation:
• Showed no higher disease incidence if they continued to
experience starvation conditions later in life
• Had higher rates of certain chronic diseases if they
received nutritionally adequate diets later in life
The mismatch in nutrient availability (low during
development, high during adulthood) resulted in maladaptive
fetal programming that led to the higher disease incidence
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Maladaptive Fetal Programming2
A similar type of mismatch can be seen in the modern
obesogenic environment
• If a fetus is exposed to poor nutrition (diet high in kcals but
low in micronutrients), s/he is more likely to experience
obesity and insulin resistance as an adult
• Maternal obesity, gestational diabetes, and overfeeding in
early life may similarly program offspring toward
maladaptive physiological responses to overnutrition in
adulthood
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DOHaD and Disease Prevention
Disease prevention during development may be as effective
as, or even more effective than, prevention in adulthood or
treatment after disease onset
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Physical Activity During Pregnancy 1
Exercise is important for maintaining health and reducing
stress during pregnancy
• Some strenuous physical activities should be avoided
• For example maximal load strength training and high-intensity
interval training
• Most pregnant women can safely:
• Walk
• Swim
• Cycle
• Engage in other aerobic activities
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Physical Activity During Pregnancy 2
Prenatal yoga is a great
activity for improving
flexibility, reducing stress,
and cultivating mindfulness
During later stages, women should avoid activities with
increased risk of impact injuries to the abdomen (“contact”
sports) or falling, such a gymnastics, surfing, downhill or
water skiing, and horseback riding
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Assess Your Progress 16.3
7. Explain why the need for vitamin A, iron, and iodine
increase during pregnancy, and list some whole food
sources of these micronutrients.
8. Describe the concept of the developmental origins of
health and disease.
9. Discuss the importance of physical activity during
pregnancy and list at least three recommended activities.
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16.4 Limiting Toxin Exposure During Pregnancy
Learning Outcomes
1. Describe recommendations concerning alcohol, tobacco,
and caffeine use during pregnancy and explain the
possible effects of these substances on a developing
offspring.
2. Explain how exposure to certain environmental toxins
during pregnancy may affect fetal development.
3. Discuss potential concerns surrounding medication use
during pregnancy.
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Alcohol and Pregnancy 1
Alcohol passes freely from the mother’s bloodstream,
through the placenta, and into the fetal bloodstream
Exposure to alcohol can damage the baby's brain and other
neural tissues, which can lead to:
• Psychological problems
• Cognitive (thought process) problems
• Behavioral problems
• Death
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Alcohol and Pregnancy 2
The toxic effects of alcohol are most devastating to an
embryo
• This is the critical period when organs are forming
Unfortunately, many women are not aware that they are
pregnant during this early stage of development
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Fetal Alcohol Spectrum Disorders
Fetal alcohol spectrum disorders (FASDs) - group of
medical conditions in children who were exposed to alcohol
during gestational development
Babies born with FASDs have:
• Distinct facial abnormalities
• Potential irreversible damage to the nervous system
• Intellectual impairment
• Behavioral problems
• Potential delays in physical development
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Fetal Alcohol Syndrome 1
Fetal alcohol syndrome (FAS) – most severe form of FASD
• Characterized
by severe
birth defects
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Fetal Alcohol Syndrome 2
FAS can result in miscarriage
• The death of an embryo or fetus that occurs before the
twentieth week of gestation
Alcohol consumption during pregnancy is the leading cause
of preventable birth defects
• It is uncertain how much alcohol is safe to consume during
pregnancy
• It is unknown whether there is a particular period during
gestation when it is safe to consume alcohol
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Tobacco
Nicotine and other toxic chemicals in tobacco smoke can
cross the placenta from the maternal bloodstream increasing
the risk of:
• Stillbirths (infants born dead)
• Preterm birth
• Low birth weight
Breathing secondhand smoke reduces the amount of oxygen
that reaches the developing offspring, increasing the risk of
poor health outcomes in the baby
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Foods and Beverages of Concern 1
Caffeine is a stimulant drug that can pass through the
placenta and enter the fetal bloodstream
Caffeine may reduce the blood flow in the placenta
• May be harmful to the developing offspring
Women should limit their caffeine consumption to less than
200 mg/day during pregnancy
• This corresponds to about 1.5 cups of regular brewed
coffee
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Foods and Beverages of Concern 2
Pregnant women should be cautious about consuming foods
that can cause infection by the bacterium Listeria
monocytogenes
• Listeria infection is the third leading cause of death from
food-borne illness in the U.S.
• Women who are pregnant are more susceptible to
infection due to their immunosupressed state
• The infection can be passed to the developing offspring,
resulting in miscarriage, stillbirth, and preterm delivery
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Avoiding Listeria Infection
Women should avoid foods that increase risk of infection
during pregnancy, including:
• Raw seafood
• Cheeses
• Eggs
• Undercooked meat
• Premade meat and seafood dishes from store deli
• Unpasteurized juices
• Reheated leftovers
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Environmental Toxins
In the past few decades, the number and levels of chemical
contaminants introduced into the water, food supply, and
personal care products have increased significantly
• Many are endocrine-disrupting chemicals (EDCs) that
interfere with cell signaling
• May cause developmental abnormalities when exposure occurs
during critical periods, including gestation
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Reducing Exposure to Environmental Toxins
To reduce exposure to environmental toxins, women may:
• Eat whole foods with minimal packaging
• Cook in stainless steel cookware
• Use natural personal care products
• Avoid new furniture, paint, and carpeting
Women may also want to determine their risk of exposure to
toxic chemicals in the workplace and wear appropriate
personal protective equipment
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Lead and Pregnancy
A woman’s past or present exposure to lead (for example
from paint or lead pipes in old houses) places her developing
offspring at risk for lead toxicity
When pregnant women breathe in or swallow lead, it enters
her blood and eventually the fetal bloodstream, and may
cause:
• Miscarriage
• Preterm delivery
• Low birth weight
• Developmental delays
• Cognitive delays
Authur S. Aubry/Getty Images
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Medication Use During Pregnancy
Certain medications can contribute to poor birth outcomes
and infant health, including:
• Miscarriage
• Low birth weight
• Preterm birth
• Neurodevelopmental delay
Only a small percentage of them have been tested on
pregnant women due to ethical issues
• Pregnant women should be cautious about taking
medications, and consult their healthcare provider
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Sustainability and Your Diet
Fish and other seafood contain many important nutrients to
support a healthy pregnancy.
• According to the 2020 to 2025 Dietary Guidelines for
Americans, women who are pregnant should consume 8 to 12
ounces of seafood per week.
• However, most contain small amounts of methylmercury, a toxin
that may form naturally but is also an industrial pollutant
• Methylmercury accumulates in the tissues of fish, and is most concentrated
in large fish that eat smaller fish
• The FDA and EPA advise women who are pregnant or nursing to avoid
eating large fish, particularly swordfish, shark, king mackerel, tilefish from
the Gulf of Mexico, marlin, orange roughy, and bigeye tuna
• Methylmercury exposure during the prenatal period is associated with
nervous system damage in the offspring, which may lead to learning
disabilities.
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Assess Your Progress 16.4
10. What are the risks of using alcohol, tobacco, and
caffeine-containing products during pregnancy?
11. What are the primary foods that put women who are
pregnant at risk of L. monocytogenes infection?
12. List three environmental toxins that can harm a
developing offspring.
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16.5 Health Conditions During Pregnancy
Learning Outcomes
1. List recommendations for managing diabetes during
pregnancy.
2. Describe dangers of hypertension during pregnancy,
particularly preeclampsia.
3. Discuss maternal complications associated with anemia
during pregnancy and strategies for treating the condition.
4. Explain the effects of maternal health conditions on birth
outcomes.
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Diabetes in Pregnancy
Recommendations to manage diabetes during pregnancy
include:
• Monitoring blood glucose levels
• Eating healthy foods that are low in added sugars and
refined carbohydrates
• Participating in regular exercise
Women who have diabetes and are using insulin prior to
becoming pregnant may need to increase their insulin
dosages, especially in the third trimester
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Swelling and Hypertension in Pregnancy
During pregnancy, normal hormonal changes cause various
tissues to retain fluid (edema)
In the U.S., 6 to 8% of pregnant women between 20 and 44
years old experience high blood pressure
• Hypertension is among the leading causes of:
• Maternal death
• Preterm labor
• Complications that affect the newborn infant
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Hypertension Terms
• Gestational hypertension - form of high blood pressure
that occurs after 20 weeks of gestation and returns to
normal by 12 weeks after the baby is born (postpartum)
• Proteinuria - protein in the urine
• Preeclampsia - condition that occurs during pregnancy;
characterized by proteinuria and edema
• Eclampsia - a severe stage of preeclampsia that results in
seizures
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Gestational Hypertension
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Risk Factors for Preeclampsia
• First pregnancy
• History of preeclampsia in a previous pregnancy
• Chronic hypertension
• Younger than 18 years of age or older than 40 years of
age
• Carrying twins, triplets, or other multiples
• Diabetes or kidney disease
• Obesity
• Very low calcium and/or vitamin D intake
• African-American or American Indian ancestry
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Anemia of Pregnancy
Maternal anemia occurs when a pregnant woman has a
hemoglobin level that is less than 11 g/dL or a hematocrit that
is less than 33%
• Hematocrit is the ratio of red blood cells to total blood
volume
There are two main causes of anemia during pregnancy:
• Expansion of maternal blood volume
• Poor dietary intake of iron
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Effects of Maternal Health on Birth Outcomes
Health problems during pregnancy can harm the developing
offspring and have negative effects on birth outcomes, such
as:
• Early (preterm) birth
• Suboptimal birth weight
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Low Birth Weight1
An infant’s weight at birth is a good indicator of overall health
status
Low birth weight (LBW) - a birth weight that is less than
2,500 g (5.5 lb)
• Many health conditions during pregnancy can cause an
infant to have a LBW
LBW infants may experience feeding problems and not reach
developmental milestones when normally expected
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Low Birth Weight2
Women with a greater chance of delivering an LBW infant
are those who:
• Do not gain the recommended minimum weight during
pregnancy
• Experience anemia
• Have low intake of certain nutrients
• Are exposed to certain chemicals
• Are diagnosed with preeclampsia
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High Birth Weight1
High birth weight (HBW) - birth weight that is greater than
4,000 g (approximately 8.8 lb)
HBW infants may be more susceptible to certain diseases
later in life
Women with a greater chance to give birth to an HBW infant
are those who:
• Are obese
• Gain too much weight during pregnancy
• Have diabetes
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High Birth Weight2
Large babies are difficult to deliver vaginally
• Often require birth by caesarian section (C-section), the
surgical removal of the baby from the mother’s uterus
• Vaginal delivery results in effective transfer of gut microbial
populations from the mother to the infant
• In C-section deliveries, this transfer does not occur
• The infant acquires its first gut bacteria from the hospital or other
external environment
• Can experience gut microbial dysbiosis
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Assess Your Progress 16.5
13. Discuss the differences between pregnancy-related and
chronic health conditions.
14. Describe preeclampsia and eclampsia.
15. Identify contributing factors to anemia during pregnancy.
16. What factors contribute to low and high infant birth
weights?
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16.6 Lactation and Breastfeeding
Learning Outcomes
1. Describe the physiology of breast tissue and the
hormones that are involved in milk production.
2. Discuss the general recommendations for the duration of
breastfeeding.
3. Summarize the potential advantages and disadvantages
of breastfeeding for new mothers.
4. Describe the nutritional recommendations for
breastfeeding women.
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Trends in Breastfeeding
In the late 1940s, feeding infants a cow milk-based formula
became popular
• Breastfeeding rapidly declined among new mothers
By 1972, only 22% of infants in the U.S. were breastfed,
most of them born to women who could not afford infant
formula
Breastfeeding has increased in popularity as information
about the benefits of the practice emerged
• In 2017, 84% of babies born in the U.S. had been
breastfed at some point
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Physiology of Milk Production and Lactation
Lactation - the production of milk by mammary glands
Mammary gland cells synthesize and incorporate into milk:
• Lactose
• Proteins
• Fatty acids
The cells also pull vitamins and minerals from the mother’s
bloodstream and add them to milk
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Lactation
Women house adipose tissue
and mammary glands in the
breast
• Cells that line the mammary
gland called mammary
alveoli produce milk
• The mother’s nutritional
status influences the
nutritional quality of the milk
she produces
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Hormones Involved in Lactation
After delivery, progesterone and estrogen levels in the
mother decrease
• Triggers the release of prolactin, the hormone that
stimulates milk production
Oxytocin is a hormone that stimulates the release of milk
from the breast
• The milk is released through nipple pores, tiny holes at the
tip of the nipple
Let-down reflex - reflex that enables milk to be released
from breasts
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Let-Down Process
SDI Productions/E+/Getty Images
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Stages of Lactation1
Colostrum - form of milk that is secreted from a woman’s
breast during the first few days after birth
• High in protein, including immune factors
• High in minerals
• Very important first food for babies, needed to support:
• Early growth and development
• The function of the baby’s immature immune system
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Stages of Lactation2
Transitional milk - combination of colostrum and mature
milk
• Produced by the end of the first week
• Higher in lactose than colostrum
Mature milk - form of milk that is secreted by the breast
about 2 weeks after delivery
• Higher in fat, carbohydrates, certain amino acids, and
vitamins
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Milk Changes Within a Feeding
Human milk also changes within a single feeding the breast
about 2 weeks after delivery
• Foremilk is milk produced at the beginning of a feeding
• High in lactose, which stimulates the infant to continue feeding
• Hindmilk is milk produced at the end of a feeding
• High in fat, which satiates the infant in order to end a feeding
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Supply and Demand
A lactating woman typically produces over 3 cups of milk per
day
Milk production relies on supply and demand
• The more the infant feeds (demands), the more milk the
mother will produce (supply)
• If milk is not fully removed from the breasts, milk
production slows
• Likely occurs when infants are not hungry because they have been
given formula or solid foods to supplement breast milk feedings
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Recommendation for the Duration of Breastfeeding
The American Academy of Nutrition and Dietetics (AND),
American Academy of Pediatrics (AAP), and ACOG,
recommend that:
• New mothers breastfeed their babies exclusively for 6
months
• Even when other foods or formula are introduced, that the
infant continue to receive some breast milk throughout the
first year of life
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Dietary Planning for Lactating Women1
Milk production requires approximately 800 kcal every day
• These energy needs can be met by adding only about 300
to 400 kcal to a woman’s prepregnancy EER
• Some of the energy for milk production comes from the fat
stores that women accumulate during pregnancy
No special foods are necessary to sustain milk production,
but the nutrient content of milk can change depending on the
mother’s diet
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Dietary Planning for Lactating Women2
A woman who breastfeeds her baby should:
• Limit her intake of alcohol- and caffeine-containing
beverages
• Her body secretes these drugs into her milk
• Check with her healthcare provider before using any
medications, even OTC and herbal products
• They may cross into her milk
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Did You Know? – Herbal Teas for Lactation
Insufficient milk production is a major determinant of the
ability of new mothers to continue breastfeeding
• Mothers of preterm infants often have difficulty producing
enough milk to fully nourish their infant.
• Some herbal teas contain galactogogues, substances that
promote milk production
• Stinging nettle (Urtica dioica and Urtica urens), has been shown to
safely increase milk production in mothers of preterm infants
compared to women consuming a placebo fruit-based tea
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Benefits of Breastfeeding1
Breastfeeding can provide many benefits for the mother
• Oxytocin helps shrink uterus to its prepregnancy size
• Lowered risks of breast and ovarian cancers, as well as
type 2 diabetes—if they did not have gestational diabetes
• The physical contact between mother and infant promotes
a strong emotional bond and may reduce the mother’s risk
of postpartum depression
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Benefits of Breastfeeding2
Many women find that breastfeeding is more convenient and
economical than feeding infant formula
• Mothers can avoid the need to purchase, prepare, and
store formula, which can be inconvenient and costly
• Breast milk is always fresh, ready to feed, and
compositionally optimal to meet the changing nutritional
needs of the infant during development
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Challenges of Breastfeeding1
Breastfeeding can be accompanied by unforeseen
challenges
• Many consumed substances can be transferred to breast
milk, including alcohol and certain prescription
medications
• Women may not be able to breastfeed if they:
• Require certain types of medications that pose a risk to the infant
• Have a serious chronic infectious disease, particularly HIV or active
tuberculosis, which may be transmitted to the infant through breast
milk
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Challenges of Breastfeeding2
Women may be hesitant to breastfeed because they think it
will interfere with returning to school or work
• Most employers allow breaks and provide a room so that
women can pump milk and store it for later use
• Many educational programs provide support for the
mother and immediate family members
• Many hospitals have a certified lactation consultant on
staff to support new mothers
• Breastfeeding support groups, such as the La Leche
League, are also available
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Assess Your Progress 16.6
17. What are the three stages of breast milk production?
18. In the United States, what is the recommended duration
for exclusively breastfeeding an infant?
19. List three advantages of breastfeeding for the mother
and three possible challenges.
20. How does a mother's diet affect the nutritional quality of
her milk?
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Case Study1
Preconception diet
Jia and Ravi have decided that they want to start trying to get
pregnant, now that Jia has secured a good job as a chemical
engineer. They visit a healthcare provider who gives them
advice on planning for pregnancy and suggests a prenatal
vitamin for Jia.
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Case Study2
Jia’s typical breakfast is a double espresso with a large
muffin from a coffee shop. Since Jia is very busy, her other
meals are usually pre-packaged, processed foods.
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Case Study3
1. Explain to Jia why it is important that she begin a healthy
diet now, before she becomes pregnant.
2. Provide Jia with an example of an easy-to-prepare,
nutrient-dense breakfast and lunch menu that she can
make at home.
3. Besides diet, what are some other lifestyle modifications
that Jia could make to improve her health prior to
conception?
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