Micronutrient Information Center

Summary

Nutrient needs during pregnancy are increased in order to support the growth of the fetus while maintaining the mother’s health. This increased need is met by a combination of physiological adaptations by the mother’s body and increased nutrient intake from food and dietary supplements.

For some micronutrients, such as folate, iron, iodine, and zinc, the requirement is substantially increased. For other micronutrients, the requirement is slightly increased (magnesium, vitamin C) or unchanged (calcium, vitamin D, vitamin E), yet it remains important to meet the recommended levels of intake for a healthy pregnancy. In the United States, several of these micronutrients are considered shortfall nutrients, meaning that they are underconsumed by eating a typical American diet. In the developing world, iron, folate, vitamin A, and iodine are in scant supply and their deficiency during pregnancy can contribute to multiple adverse outcomes in the mother and newborn. Routine supplementation with folic acid (the synthetic form of folate) is universally recommended. Routine supplementation with iron is recommended in areas of the world with high rates of malnutrition and anemia; in the US and other developed nations, the need for iron supplementation is generally evaluated by a healthcare professional on an individual basis.

Condition Overview

Nutrient needs during pregnancy are increased. This is because the mother requires extra energy, building blocks, and cellular assistants to support the development and growth of the new baby. Increased nutrient needs during pregnancy are met by a combination of physiological adaptations and increased dietary intake by the mother.

Physiological adaptations

1. Hormonal changes - hormonal changes during pregnancy help to direct nutrients to the developing fetus. Hormones like human chorionic gonadotropin (hCG), human placental lactogen (hPL), and estrogen stimulate maternal fat breakdown, increase bone turnover, and oppose the action of insulin. Overall, these changes allow glucose, amino acids, fatty acids, and micronutrients to flow to the developing fetus rather than being stored in maternal tissues.

2. Increased absorption and reduced excretion - alterations in nutrient absorption and excretion also help the mother meet the increased nutrient demands of pregnancy. For example, gastrointestinal absorption of calcium, iron, zinc, and vitamin B₁₂ are increased compared to that of nonpregnant women. Pregnant women also reduce the amount of selenium excreted in the urine.

3. Mobilization of mineral stores - the mother can access stores of calcium (from the skeleton) and iron (from a storage protein called ferritin) to meet the demands of the developing fetus. Maternal stores of calcium and iron can be replenished by ingesting these micronutrients at the recommended levels of intake (Table 2).

Dietary intake

1. Energy (calories) - energy requirements increase by an estimated 300 kcal/day during the second and third trimesters of pregnancy, when the baby is rapidly increasing in size. Because the requirement for most micronutrients increases more than the requirement for energy, women are advised to improve diet quality and get sufficient exercise during pregnancy in order to meet micronutrient requirements while maintaining a healthy weight. Appropriate weight gain during pregnancy (neither too little nor too much) helps to improve maternal and child health outcomes (Table 1).

2. Water - The fluid found inside and around our cells, tissues, and organs is critical for our body’s ability to function — body water maintains our blood volume, helps transport nutrients and remove waste products, regulates body temperature, and is a critical component of every cell in our body. During pregnancy, extra fluid is needed to maintain the amniotic fluid that surrounds, cushions, and protects the developing fetus and to support an increase in maternal blood volume. Adequate fluid intake also helps combat fluid retention, constipation, and dehydration. The recommended intake for total water is 3 liters (12.7 cups)/day from drinking water, beverages, and food; of this amount, about 10 cups/day should come from water and other beverages.

3. Macronutrients (protein, carbohydrate, fat)

• Protein - protein needs increase by approximately 25 additional grams/day; many women already consume this amount of protein. Good protein sources include low-fat dairy products, lean meat and poultry, fish, eggs, legumes, nuts, and seeds.
• Carbohydrate - carbohydrate intake should be at least 175 grams/day. The majority of carbohydrate intake should come from whole grain breads and cereals, fruit, vegetables, and legumes.
• Fat - consumption of the right kind of fat is important. Pregnant and nonpregnant women alike should replace saturated and trans fat with mono- and polyunsaturated fat from vegetable oils, nuts, and oily fish. By consuming the recommended amounts of the essential fatty acids, linoleic acid (omega-6 PUFA) and α-linolenic acid (omega-3 PUFA) (Table 2), pregnant women will meet their needs for other fatty acids, such as arachidonic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).

4. Micronutrients (vitamins, nutritionally essential minerals, and choline) - For several micronutrients, the recommended levels of intake are increased compared to nonpregnant women of the same age (Table 2). Considering that many women do not meet the recommended levels of intake for many micronutrients to begin with, special effort should be made to meet the higher nutrient needs of pregnancy. This includes making healthful dietary choices and possibly taking a dietary supplement under the supervision of a qualified healthcare provider.

Table 2 also includes the tolerable upper intake level (UL) for pregnant adult women. The UL is the highest level of daily intake that is likely to pose no risk of adverse health effects in almost all individuals of a specified life stage. While intakes above the UL are not advised for any micronutrient, vitamin A excess during pregnancy can be particularly detrimental, causing heart defects and facial malformations in the newborn.

References

• Micronutrient Information Center in-depth article on Pregnancy and Lactation
• Nutrition: An Applied Approach, fourth edition. Janice Thompson and Melinda Manore. Chapter 15, Nutrition Through the Lifecycle: Pregnancy and the First Year of Life
• Present Knowledge in Nutrition, 12^th edition. Chapter 39, Lindsay Allen
• Scientific Report of the 2015 Dietary Guidelines Advisory Committee, Office of Disease Prevention and Health Promotion
• Dietary Reference Intake (DRI) reports
• Office on Women's Health, US Department of Health and Human Services

Nutrition Research

Essential Fatty Acids

What they do

General

• Essential fatty acids are a type of polyunsaturated fatty acid (PUFA) that cannot be synthesized in the body and must come from the diet.
• Essential fatty acids are structural components of every cell in the body and are converted to compounds that influence inflammation and immunity.
• There are two classes of essential fatty acids: omega-6 PUFA and omega-3 PUFA.

Pregnancy-specific

• The last trimester of pregnancy and first six months of postnatal life are critical periods for the accumulation of the long-chain omega-3 PUFA, docosahexaenoic acid (DHA), in the brain and retina of the baby.

What we know

• Higher intakes of long-chain omega-3 PUFA from fish and seafood during pregnancy are associated with improved developmental outcomes in offspring.
• Fetal tissue can form DHA from the omega-3 PUFA α-linolenic acid. If the maternal diet meets omega-3 PUFA (α-linolenic acid) and omega-6 PUFA (linoleic acid) requirements, supplementation with DHA provides no further benefit to the fetus.
• Supplementation with long-chain omega-3 PUFA during pregnancy does not influence the risk of preterm birth, gestational diabetes mellitus, pregnancy-induced hypertension, or preeclampsia.
• There is some evidence that long-chain omega-3 PUFA supplementation may result in a modest increase in the length of gestation (1.6 days), especially in women with low omega-3 PUFA consumption.

For references and more information, see the sections on Visual and neurological development and Gestation and pregnancy in the Essential Fatty Acids article.

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Biotin

What it is

General

• Biotin is a B-vitamin that helps make and breakdown glucose, fatty acids, and some amino acids.

Pregnancy-specific

• During pregnancy, biotin is needed for these same essential cellular activities, which are taking place at higher rates during fetal development.

What we know

• A substantial number of pregnant women (30 to 50 percent) have an increased urinary excretion of 3-hydroxyisovaleric acid (3-HIA), a marker of biotin status. It is not known whether this increase in urinary 3-HIA excretion is normal for pregnant women or indicative of low biotin intake relative to need.
• Although some animals are very sensitive to biotin deficiency during pregnancy, a link between biotin deficiency and adverse effects in the mother and the developing fetus have not been observed in humans.
• The recommended level of biotin intake (30 micrograms/day) is the same for pregnant and nonpregnant women (Table 2). It is estimated that a typical mixed diet provides 30 to 60 micrograms of biotin/day.

For references and more information, see the section on Biotin in the Pregnancy and Lactation article.

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Calcium

What it is

General

• Calcium is an essential mineral that is a structural component of bones and teeth, is required for proper nerve transmission and muscle contraction, and influences blood pressure.

Pregnancy-specific

• Approximately 250-350 milligrams (mg)/day of calcium is transferred from the mother to the fetus, primarily in the last trimester.
• Low-calcium intake during pregnancy may cause hormonal changes that lead to smooth muscle cell contraction, blood vessel narrowing, and the retention of sodium and fluid. These changes can contribute to the development of pregnancy-induced hypertension (PIH) and preeclampsia.

What we know

• Intestinal calcium absorption efficiency doubles during pregnancy, and the mineral can be temporarily mobilized from the skeleton to support fetal needs for calcium.
• Observational studies suggest an inverse relationship between dietary calcium intake and the occurrence of PIH. In other words, the lower the calcium intake, the higher the risk of developing PIH.
• Randomized controlled trials report that calcium supplementation during pregnancy (more than 1,000 mg/day) is associated with a 35 percent lower risk of high blood pressure and 55 percent lower risk of preeclampsia; the risk reduction for preeclampsia is even stronger for women considered to be at high risk for the condition (78 percent lower risk) and women with low dietary intake of calcium (64 percent lower risk).
• Although the RDA for calcium is the same for pregnant and nonpregnant women, calcium is considered a shortfall nutrient in the diet and many women do not meet the recommended 1,000 mg/day.

For references and more information, see the section on Calcium in the Pregnancy and Lactation article.

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Choline

What it does

General

• Choline is an essential component of cell membranes, influences the production of several important neurotransmitters, and helps transport and metabolize fatty acids and cholesterol.
• Additionally, choline helps convert homocysteine to methionine, an amino acid used in countless essential cellular activities.
• Choline can be made by the body in small amounts but not enough to support health. Therefore, choline must also be obtained from dietary sources and is considered an essential nutrient.

Pregnancy-specific

• Choline is needed for embryonic and fetal brain development.
• Animal studies indicate that maternal intake of choline during pregnancy might affect intellectual abilities in the offspring.

What we know

• The mother delivers large amounts of choline to the fetus across the placenta, placing an increased demand on maternal stores of choline during pregnancy.
  • high levels of estrogen during pregnancy lead to increased choline production.
  • pregnant women are encouraged to consume choline-rich foods, such as eggs, meat, and seafood.

• The relationship between choline and the risk of neural tube defects is unclear at this time.
  • There have been some reports that low dietary intake or low blood concentrations of choline are associated with a higher risk of NTDs; other reports have found no association.
  • It is not known if supplementation with choline will lower the occurrence of NTDs.

For references and more information, see the section on Choline in the Pregnancy and Lactation article.

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Chromium

What it does

General

• Chromium is a mineral that enhances the action of insulin.

Pregnancy-specific

• Chromium supplementation is being investigated for the control of blood glucose in type 2 diabetes mellitus; the role of chromium supplementation in gestational diabetes mellitus (GDM) is also under investigation.

What we know

• Observational studies report mixed results regarding serum chromium concentration and GDM.
  • Two studies found no relationship; one study found that women with GDM have lower serum chromium concentration compared to pregnant women without GDM.
  • Further complicating matters, it is not known if serum chromium concentration accurately reflects tissue chromium levels or chromium status during pregnancy.

• One small randomized controlled trial in 24 women with GDM found that supplementation with chromium picolinate reduced fasting blood glucose and insulin levels. Importantly, insulin therapy was still required to normalize elevated blood glucose in this study population.
• More research is needed to determine whether chromium supplementation is useful in the treatment of GDM.

For references and more information, see the section on Chromium in the Pregnancy and Lactation article.

Folate (folic acid)

What it does

General

• Folate is a B-vitamin required for DNA synthesis and the formation of new cells.
• Additionally, the B-vitamins folate, vitamin B₁₂, and vitamin B₆ work together to convert homocysteine to methionine, an amino acid used in countless essential cellular activities.
• Folate is present naturally in food; folic acid is a synthetic form of folate that is found in supplements and fortified products. Although folic acid is better absorbed across the digestive tract, both forms enter the same biochemical pathway and are indistinguishable at the cellular level.

Pregnancy-specific

• The developing embryo and fetus require folate to form new cells, tissues, and organs.
• An especially sensitive event that relies on a sufficient amount of folate is the closure of the neural tube, the precursor to the brain and spinal cord. Closure of the neural tube occurs very early in pregnancy, by the sixth week of gestation, a time when many women do not realize they are pregnant.

What we know

• Lower blood folate concentrations are associated with a higher risk of neural tube defects (NTDs).
• Randomized controlled trials demonstrate that periconceptional supplementation with folic acid dramatically reduces the occurrence of NTDs.
• In order to reduce the risk of NTDs, there is wide agreement that all persons capable of becoming pregnant take supplemental folic acid. The US Preventive Services Task Force recommends a daily supplement of 400 to 800 micrograms of folic acid for those planning or capable of pregnancy.
• Persons who have had a previous NTD-affected pregnancy may be advised to consume up to 5,000 micrograms/day of folic acid when they are planning to become pregnant. This dosage should be prescribed and monitored by a healthcare provider.
• Throughout pregnancy, low blood folate concentrations may be associated with other adverse pregnancy outcomes. Elevated blood homocysteine, an indicator of low folate status, has been associated with an increased risk of preeclampsia, premature delivery, and low birth weight. For this reason, folic acid supplementation should continue throughout pregnancy. 

For references and more information, see the section on Adverse pregnancy outcomes in the Folate article.

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Iodine

What it does

General

• Iodine is a mineral that is a major structural component of thyroid hormones. Thyroid hormones regulate many key metabolic and enzymatic reactions that are essential for life.

Pregnancy-specific

• Iodine is needed for maternal thyroid hormone production.
• During pregnancy, thyroid hormone is needed for myelination of the central nervous system and is essential for normal brain development.

What we know

• Maternal iodine deficiency has been associated with increased incidence of miscarriage, stillbirth, and birth defects.
• Severe iodine deficiency during pregnancy can result in hypothyroidism and brain damage and mental deficiency in the offspring.
• Even mild forms of maternal iodine deficiency may have adverse effects on intellectual development and mental abilities in the offspring.
• The Recommended Dietary Allowance for iodine is significantly increased during pregnancy, from 150 to 220 micrograms/day.
  • Universal salt iodization has helped to dramatically reduce iodine deficiency worldwide.
  • Still, to ensure the higher requirement is met, the American Thyroid Association recommends that women take a multivitamin containing 150 micrograms of potassium iodide daily during preconception (ideally starting 3 months before a pregnancy), pregnancy, and lactation and advises all pregnant women to reach a daily intake of 250 micrograms of iodine — total combined from diet and supplements.
• The American Thyroid Association advises against iodine intakes of 500 micrograms a day or more from iodine, potassium iodide, and kelp supplements during pregnancy and lactation.

For references and more information, see the section on Supplements in the Iodine article.

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Iron

What it does

General

• Iron is required for the synthesis of hundreds of essential proteins, facilitates oxygen transport and storage, participates in energy production, and assists antioxidant enzymes.
• Dietary iron is found in two forms: heme and nonheme iron. Heme iron comes mainly from meat, poultry, and seafood. Nonheme iron is found in plants, dairy products, meat, fortified food, and dietary supplements.

Pregnancy-specific

• The developing fetus needs iron for the growth and development of all tissues and organs.
• The mother requires iron to meet the increased production of red blood cells that transport oxygen to the developing fetus; too little iron can lead to iron-deficiency anemia.

What we know

• The Recommended Dietary Allowance for iron is significantly increased during pregnancy, from 18 to 27 milligrams (mg)/day.
• Intestinal absorption of dietary iron increases during the second and third trimesters, yet many women still develop iron deficiency or iron-deficiency anemia during pregnancy.
• Severe iron deficiency during pregnancy has been associated with increased risk of low-birth-weight infants, premature delivery, and infant mortality.
• In developing countries, where anemia is widespread and there is a high risk of anemia among pregnant women, routine iron supplementation reduces the risk of iron-deficiency, anemia, preterm delivery, and low-birth-weight infants. Doses above 60 mg/day of elemental iron are associated with an increased risk of side effects.
• In developed countries, where there is an average risk of anemia among pregnant women, supplementation with iron improves maternal iron status and decreases the risk of anemia at term.

For references and more information, see the section on Iron in the Pregnancy and Lactation article.

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Magnesium

What it does

General

• Magnesium is an essential mineral that serves as a structural component of the skeleton; assists in hundreds of enzymatic reactions involved in the synthesis of energy, DNA, and proteins; and is required for proper nerve conduction and muscle contraction.

Pregnancy-specific

• Magnesium is needed for essential enzymatic reactions and the formation of new tissue (including bone) that takes place during embryonic and fetal development.
• Intravenous magnesium sulfate is included in the medical care of preeclampsia, eclampsia, and neuroprotection of premature infants.

What we know

• The RDA for magnesium is slightly increased during pregnancy, from 310 to 350 milligrams (mg)/day.
  • Magnesium is considered a shortfall nutrient in the diet, meaning that magnesium is underconsumed by eating the typical American diet.
  • Good sources of magnesium include green leafy vegetables, whole grains, and nuts.

• Regarding the medical management of certain pregnancy complications, intravenous magnesium sulfate causes blood vessel dilation in the brain and periphery and is used by physicians to prevent seizures that may occur in association with preeclampsia-eclampsia in late pregnancy or during labor.

For references and more information, see the section on Pregnancy complications in the Magnesium article.

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Riboflavin

What it does

General

• Riboflavin is a B-vitamin that helps convert food into useable energy and assists several metabolic and antioxidant enzymes.

Pregnancy-specific

• Riboflavin is needed to support the increased growth and energy utilization that occurs during pregnancy.
• While it is unclear what causes preeclampsia during pregnancy, riboflavin deficiency could compromise antioxidant enzyme activity, leading to oxidative stress and an increased risk of preeclampsia.

What we know

• Very few studies have investigated the link between riboflavin and preeclampsia.
  • One observational study in pregnant women at high risk for preeclampsia found that those who were riboflavin deficient were 4.7 times more likely to develop preeclampsia than those who had adequate riboflavin nutritional status.
  • One small randomized controlled trial in pregnant women at high risk for preeclampsia found that supplementation with 15 mg riboflavin daily did not prevent preeclampsia.

• The RDA for riboflavin is slightly increased during pregnancy, from 1.1 to 1.4 milligrams (mg)/day.
  • Most plant and animal food contains riboflavin.
  • Dietary surveys indicate that usual intake among Americans (≥4 years of age) is 2.2 mg/day. 

For references and more information, see the section on Deficiency in the Riboflavin article.

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Vitamin A

What it does

General

• Vitamin A is a fat-soluble vitamin that is essential for normal vision, reproduction, cell growth and development, and immune function.
• Preformed vitamin A (retinol) is found in animal organs and fortified products.
• Provitamin A carotenoids (α-carotene, β-carotene, and β-cryptoxanthin) are compounds found in yellow- and orange-colored fruit and vegetables that are converted to retinol by the liver.

Pregnancy-specific

• Vitamin A is involved in cellular events that regulate the formation of the vertebrae and spinal cord, vital organs (such as the heart and lungs), eyes, ears, and limbs. Severe vitamin A deficiency in animal models results in birth defects to these structures.
• Vitamin A deficiency impairs iron mobilization from stores, impairs the synthesis of hemoglobin, and may exacerbate iron-deficiency anemia.
• Because vitamin A is also required for normal functioning of the retina, dim-light vision, and color vision, vitamin A deficiency can lead to impaired dark adaptation (night blindness) and in severe cases, blindness.

What we know

• Vitamin A deficiency during pregnancy has been linked to impaired immunity, increased susceptibility to infection, increased risk of maternal death and disease, and night blindness.
  • In regions of the world where vitamin A deficiency is a severe public health problem (mainly Africa and Southeast Asia), the World Health Organization (WHO) recommends vitamin A supplementation (up to 10,000 IU daily or 25,000 IU weekly) starting in the second or third trimester for the prevention of night blindness.
  • In developing countries, co-supplementation with vitamin A and iron may be more effective in reducing iron-deficiency anemia than iron supplementation alone.

• Consumption of excess preformed vitamin A during pregnancy can cause birth defects.
  • The most critical period for damage appears to be during the first trimester, resulting in birth defects affecting the cardiovascular system, central nervous system, facial area, and thymus (an organ involved in immune cell production).
  • Birth defects have not been observed at supplemental doses less than 3,000 micrograms (10,000 IU)/day of preformed vitamin A.

For references and more information, see the section on Vitamin A in the Pregnancy and Lactation article.

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Vitamin B₆

What it does

General

• Vitamin B₆ helps convert food into usable energy and assists in the formation of neurotransmitters, red blood cells, proteins, and DNA.
• Additionally, the B-vitamins folate, vitamin B₁₂, and vitamin B₆ work together to convert homocysteine to methionine, an amino acid used in countless essential cellular activities.

Pregnancy-specific

• Because a developing embryo and fetus have high rates of proliferation, they require vitamin B₆ to form new cells, tissues, and organs.
• Vitamin B₆ has been used since the 1940s to treat nausea during pregnancy.

What we know

• Short-term supplementation with high-dose vitamin B₆ (10 mg/day) may help relieve nausea in pregnancy.
• The American and Canadian Colleges of Obstetrics and Gynecology recommend the use of a delayed-release formulation of pyridoxine hydrochloride (vitamin B₆) plus doxylamine succinate (an antihistamine) as first-line therapy for nausea and vomiting during pregnancy. Such therapy should be conducted under the care of a qualified healthcare provider.

For references and more information, see the section on Nausea and vomiting during pregnancy in the Vitamin B₆ article.

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Vitamin B₁₂

What it does

General

• Vitamin B₁₂ helps convert food into usable energy, is required for proper nerve function, and assists in the formation of red blood cells, proteins, and DNA.
• Additionally, the B-vitamins folate, vitamin B₁₂, and vitamin B₆ work together to convert homocysteine to methionine, an amino acid used in countless essential cellular activities.

Pregnancy-specific

• Because a developing embryo and fetus have high rates of proliferation, they require vitamin B₁₂ to form new cells, tissues, and organs.

What we know

• Absorption of vitamin B₁₂ is more efficient during pregnancy.
• Inadequate dietary intake of vitamin B₁₂ causes elevated homocysteine levels, which has been associated with adverse pregnancy outcomes, such as preeclampsia, premature delivery, low birth weight, very low birth weight, and stillbirth.
• Low serum levels of vitamin B₁₂ during pregnancy have been linked to an increased risk for neural tube defects (NTDs). However, the effect of vitamin B₁₂ supplementation on the risk of NTDs has not yet been evaluated in randomized controlled trials.
• To ensure a daily intake of 6 to 30 micrograms of vitamin B₁₂ in a form that is easily absorbed, the Linus Pauling Institute recommends that women who are planning a pregnancy take a daily multivitamin supplement or eat a breakfast cereal fortified with vitamin B₁₂.

For references and more information, see the section on Vitamin B₁₂ in the Pregnancy and Lactation article.

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Vitamin C

What it does

General

• Vitamin C is a water-soluble vitamin that neutralizes a variety of reactive oxygen species and recycles important cellular antioxidants.
• Vitamin C is also a cofactor in numerous enzymatic reactions involved in the making of collagen, L-carnitine, and several neurotransmitters, and in the regulation of gene expression.

Pregnancy-specific

• Vitamin C is required to make collagen, a component of skin, blood vessels, tendons, and the organic matrix of bone.
• Oxidative stress has been implicated in the development of preeclampsia; thus, antioxidant vitamins (vitamin C and vitamin E) may be important in preventing the condition.

What we know

• Two pooled analyses of randomized controlled trials found no benefits of vitamin C supplementation, alone or in combination with other supplements, on pregnancy adverse events, with the exception of a reduced risk of placental abruption and a significant increase in gestational age at birth.
• Preliminary findings also suggested that vitamin C supplementation during pregnancy might protect against the increased risk of adverse pregnancy events and childhood respiratory illness in smoking mothers.

For references and more information, see the section on Adverse pregnancy outcomes in the Vitamin C article.

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Vitamin D

What it does

General

• Vitamin D is a fat-soluble vitamin that helps maintain calcium and phosphorus balance, promotes bone health, regulates immune function, and influences cell growth and development.

Pregnancy-specific

• Vitamin D is needed for the absorption of calcium and for the formation of new tissue (mainly bone) that takes place during embryonic and fetal development.

What we know

• Vitamin D insufficiency (defined by the Institute of Medicine as serum 25-hydroxyvitamin D between 12 to 19 nanograms [ng]/milliliter [mL]) has been linked to an increased risk for a number of adverse outcomes in the mother and the infant.
  • For the mother: gestational diabetes mellitus, preeclampsia, and bacterial vaginosis.
  • For the infant: small-for-gestational age and low birth weight.
  • Although other adverse outcomes have been examined, no significant relationship between vitamin D insufficiency and C-section, respiratory conditions, or allergies in children have been observed.

• The requirement for vitamin D is not increased during pregnancy, but vitamin D is considered a shortfall nutrient in the diet and low vitamin D status (less than 50 nmol/L [20 ng/mL]) is common in pregnant women.

For references and more information, see the section on Adverse pregnancy outcomes in the Vitamin D article.

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Vitamin E

What it does

General

• Vitamin E is a fat-soluble vitamin that functions as an antioxidant in lipid (fat) environments.
• Vitamin E is an important antioxidant nutrient in cell membranes, where it functions to protect cells from damage caused by reactive oxygen species (ROS).

Pregnancy-specific

• Oxidative stress has been implicated in the development of preeclampsia; thus, antioxidant vitamins (vitamin C and vitamin E) may be important in preventing the condition.

What we know

• Randomized controlled trials have not found combined supplementation of antioxidant vitamins (1,000 mg/day vitamin C plus 180 mg/day of vitamin E [RRR-α-tocopherol]) to be effective in preventing preeclampsia.

For references and more information, see the section on Vitamin C and Vitamin E in the Pregnancy and Lactation article.

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Vitamin K

What it does

General

• Vitamin K is a fat-soluble vitamin that assists in blood clotting and modifies certain proteins to a calcium-binding form.
• Naturally occurring vitamin K includes a number of different vitamin K compounds, classified as either vitamin K₁ (phylloquinone) or vitamin K₂ (menaquinones).

Pregnancy-specific

• When taken during pregnancy, a number of medications may increase the risk of vitamin K deficiency and hemorrhagic disease in the newborn. These medications include warfarin, rifampin, isoniazid, and anticonvulsants.
• Transfer of vitamin K across the placenta is low, therefore all infants are born with low concentrations of vitamin K.

What we know

• Vitamin K deficiency bleeding (VKDB) develops in a small number of newborns who do not have enough vitamin K to make their blood clot.
• Intramuscular (IM) injection of vitamin K₁ to the newborn shortly after birth decreases the risk of VKDB.
• Oral administration of vitamin K to the newborn raises serum vitamin K concentration, but is associated with an increased occurrence of late VKDB (bleeding that occurs two to 12 weeks after birth).
• The American Academy of Pediatrics and several international organizations recommend prophylactic IM injection of vitamin K₁ within six hours of birth for the prevention of VKDB.

For references and more information, see the section on Vitamin K in the Pregnancy and Lactation article.

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Zinc

What it does

General

• Zinc is an essential trace mineral that is required for the synthesis of hundreds of essential proteins, facilitates oxygen transport, and assists several antioxidant enzymes.

Pregnancy-specific

• Zinc is crucial for the formation, growth, and development of the cells and tissues of the developing fetus.
• Both maternal and fetal tissues accumulate zinc over the course of pregnancy.

What we know

• The RDA for zinc is increased during pregnancy, from 8 to 11 mg/day.
• Poor nutritional status of zinc during pregnancy has been associated with a number of adverse outcomes, including preeclampsia, premature delivery, low-birth-weight newborns, and birth defects.
• Zinc supplementation in isolation is unlikely to benefit any pregnant women, whether they are from low- or high-income settings. Only administration of zinc as part of a multivitamin supplement in women with coexisting micronutrient deficiencies reduces the risk of having low-birth-weight babies.
• An emphasis on improving overall nutritional status rather than taking isolated zinc supplements is advised.

For references and more information, see the section on Pregnancy complications and adverse pregnancy outcomes in the Zinc article.

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Alcoholic Beverages

What it does

General

• Alcoholic beverages contain ethanol and other ingredients with bioactive properties that may affect health.
• Although moderate alcohol consumption (no more than 2 drinks/day for men and 1 drink/day for women), is associated with beneficial effects in the cardiovascular system, pregnancy is a special case in which potential risks associated with alcohol consumption outweigh the benefits.

Pregnancy-specific

• Ethanol is a teratogen, a substance that can cause abnormal development in the fetus.
• Alcohol in the mother’s blood readily crosses the placenta to the developing embryo or fetus.

What we know

• There is no known safe amount or safe time to drink alcohol during pregnancy.
• Alcohol consumption, especially during the first trimester, increases the risk of preterm birth and infants born small for gestational age.
• Moderate alcohol consumption during pregnancy has been associated with problems with memory, attention, learning, and behavior in the offspring.
• Regular heavy alcohol consumption (>4 drinks/day) and binge drinking (4 or more drinks per occasion) during pregnancy can lead to fetal alcohol syndrome, a group of lifelong physical, behavioral, and intellectual disabilities in the offspring.

For references and more information, see the section on Pregnancy in the Alcoholic Beverages article.

Coffee

What it does

General

• Coffee is a complex mixture of chemicals. In addition to caffeine, coffee contains several phytochemicals that can influence human health.

Pregnancy-specific

• Caffeine crosses the placenta and the fetus is exposed to caffeine via the umbilical cord and amniotic fluid.
• Caffeine is metabolized more slowly in pregnant women, with a half-life of about 15 hours in pregnant women compared to about five hours in nonpregnant women.

What we know

• Some, but not all, observational studies have associated high caffeine consumption with adverse effects during pregnancy, such as an increased risk of miscarriage and delivering a low-birth-weight baby.
• Women who are pregnant or planning to become pregnant should limit caffeine consumption to less than 200 milligrams (mg)/day.

For references and more information, see the section on Adverse pregnancy outcomes in the Coffee article.

This content was underwritten, in part, by a grant from Bayer Consumer Care AG, Basel, Switzerland.