Pregnancy Diet

Definition

A pregnancy diet is a healthy diet that provides all of the nutrients needed by a woman and her fetus and is free of substances that could harm the mother or child.

Origins

Recommended weight gain for pregnant women

If you are:

You should gain:

Rate per week

Underweight (BMI <18.5)

28 to 40 pounds

1-1.3 lb.

Normal weight (BMI 18.5-24.9)

25 to 35 pounds

0.8-1 lb.

Overweight (BMI 25-29.9)

15 to 25 pounds

0.5-0.7 lb.

Obese (BMI 30+)

11 to 20 pounds

0.4-0.6 lb.

Numbers are estimates based on pre-pregnancy body mass index (BMI). Rates of weight gain per week assume a gain of 1.1-4.4 lb. during the 1st trimester and apply to 2nd and 3rd trimesters only.

SOURCE: Institute of Medicine (US) and National Research Council (US) Committee to Reexamine IOM Pregnancy Weight Guidelines. “Weight Gain During Pregnancy: Reexamining the Guidelines.” Washington DC: National Academies Press, 2009. https://www.ncbi.nlm.nih.gov/books/NBK32813/doi:10.17226/12584 (accessed April 2, 2018).

Description

Most of the nutrients needed by a mother and her fetus during pregnancy can be obtained by eating a high-quality, balanced, and varied nutrient-dense diet that is rich in vitamins and minerals. The mother's diet must provide sufficient energy (calories) and nutrients to meet her usual requirements in addition to those of the growing fetus. Guidelines for a healthy diet are based around the five main food groups:

Function

Energy (calorie) requirements increase during pregnancy by a small amount. The body's increased need for certain nutrients, such as iron and calcium, can be met with little increase in overall food intake by selecting nutrient-dense foods, because the body adapts and becomes more efficient at absorbing and using these nutrients during pregnancy. However, it is necessary to increase the intake of some specific nutrients, through changes in diet and often with a doctor-recommended supplement. These nutrients include protein; the B vitamins, including thiamin (vitamin B1) and riboflavin (vitamin B2); folate; and vitamins A, C, and D. For some of these nutrients, such as protein, the majority of women in developed countries will already be consuming enough. However, for other nutrients, such as folate, dietary adjustments may be necessary to make sure that adequate amounts are consumed. Many medical practitioners recommend taking prenatal vitamins during pregnancy to ensure an adequate supply of folate and certain B vitamins. Pregnant women should discuss their nutritional needs with their doctor before beginning any vitamin supplementation.

For women with a healthy pre-pregnancy weight, the Institute of Medicine of the National Academy of Sciences recommends an average weight gain of 25–35 lb. (11–16 kg). This range is associated with the lowest risk of complications during pregnancy and labor and with a reduced likelihood of having a low-birthweight infant. However, women may vary widely in the amount of weight gained during pregnancy. Suggested gains for women who are underweight or overweight at the start of their pregnancy vary accordingly, and women who gain an excessive amount of weight are more likely to remain overweight or obese following the birth. While pregnancy should not serve as an excuse to eat more junk food, it is also not a time for restricting caloric intake, as this may lead to inadequate nutrient supplies for both the mother and fetus. Women should consult with their physicians if they have concerns about weight gain during pregnancy.

Benefits

Folate (folic acid) is essential for the normal development of the neural tube in the fetus. The neural tube develops into the brain and spinal cord and closes between the third and fourth week after conception. Most pregnant women need 800 mcg/day. Insufficient folate at this crucial time can lead to serious malformations of the spine (spina bifida) and the brain (anencephaly). Folic acid supplements are advised before conception and during the first 12 weeks of pregnancy, because research has shown that they can reduce the risk of neural tube defects such as spina bifida by around 70%. Women who have already given birth to a baby with a neural tube defect should take a larger dose under the supervision of a doctor. Extra folate in the diet is also needed throughout pregnancy. Pregnant women should also eat a diet that includes plenty of folate-rich foods such as green leafy vegetables, oranges, dried beans, and lentils. Some commercially processed foods such as breakfast cereals are also fortified with folic acid. In the United States and Canada, fortification of flour with folic acid in recent years has greatly increased folate intakes.

Extra iron is needed during pregnancy, mostly in the last two trimesters. Twenty-seven milligrams per day is usually recommended. Iron is an essential component of hemoglobin, the compound in red blood cells that carries oxygen to all parts of the body. The developing fetus needs iron to make its own stores of hemoglobin. Inadequate blood iron levels cause iron deficiency anemia, which can make the mother tired, irritable, and unable to concentrate. The risk of becoming anemic is greater during pregnancy, and anemic women are more likely to deliver a baby of low birth weight and with poor iron stores. In the United States, most recommendations advise pregnant women to take a supplement of 30 mg of ferrous iron in addition to eating a well-balanced diet. In other countries, such as the United Kingdom, supplements are advised on an individual basis when considered necessary. However, pregnant women should eat plenty of iron-rich foods, such as lean red meat, dried beans, dark green leafy vegetables, and fortified breakfast cereals. Vegetarians and vegans should be especially aware of increasing their iron intake during pregnancy. Consuming foods containing vitamin C at the same time as nonmeat iron-rich foods helps to enhance iron absorption. Examples include having a glass of orange juice (a source of vitamin C) with a bowl of cereal (containing iron) or baked beans (containing iron) with a baked potato (a source of vitamin C). Other sources of vitamin C include tomatoes, red peppers, strawberries, and broccoli.

Vitamin D is needed to absorb calcium from the diet, and an adequate supply is essential for healthy bones and teeth. Normally 600 IU (international units) per day are recommended. Calcium is essential in the formation of bone in the fetus. Intake recommendations range from 1,000–1,300 mg per day, depending on age at the time of pregnancy. Vitamin D supplements are commonly recommended for all pregnant women as a precautionary measure. Vitamin D is obtained mainly by the action of sunlight on the skin, but it is also found naturally in eggs, meat, and oily fish. In the United States, milk, some orange juice, and many fat spreads are fortified with vitamin D.

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are types of omega-3 fatty acids found in oil-rich fish (e.g., mackerel, salmon, kippers, fresh tuna, herring, trout, and sardines). These are major nutrients needed by the brain and retina, and there has been a lot of recent interest in their role in infant development. Eating fish has been associated with lower risks of preterm delivery and low birth weight. However, some fish contain mercury or other heavy metals that can be harmful. Pregnant women should consult their physicians about which fish are safest to eat during pregnancy.

KEY TERMS
Anencephaly—
A fatal hereditary defect resulting in the partial to complete absence of a brain and spinal cord.
Basal metabolic rate—
The number of calories the body burns at rest to maintain normal body functions.
Fiber—
Comes in two forms: Insoluble fiber moves through the digestive system almost undigested and gives bulk to stools, and soluble fiber dissolves in water and helps keep stools soft.
Folic acid—
The synthetic form of the B vitamin folate (B9), found in supplements. Folate is needed to produce red blood cells.
Iron deficiency anemia—
A condition characterized by an inability to make red blood cells of sufficient size; symptoms include fatigue, shortness of breath, headaches, and weakened immunity. It is common in pregnancy.
Low birth weight—
Infants are considered to be of low birth weight if they are born after the normal gestational period (38–42 weeks) but weigh less than 5.5 lb (2.5 kg) at birth.
Neural tube defects—
Neural tube defects are serious birth defects that involve incomplete development of the partial to complete absence of a brain and spinal cord.
Basal metabolic rate—
The number of calories the body burns at rest to maintain normal body functions.
Fiber—
Comes in two forms: Insoluble fiber moves through the digestive system almost undigested and gives bulk to stools, and soluble fiber dissolves in water and helps keep stools soft.
Folic acid—
The synthetic form of the B vitamin folate (B9), found in supplements. Folate is needed to produce red blood cells.
Iron deficiency anemia—
A condition characterized by an inability to make red blood cells of sufficient size; symptoms include fatigue, shortness of breath, headaches, and weakened immunity. It is common in pregnancy.
Low birth weight—
Infants are considered to be of low birth weight if they are born after the normal gestational period (38–42 weeks) but weigh less than 5.5 lb (2.5 kg) at birth.
Neural tube defects—
Neural tube defects are serious birth defects that involve incomplete development of the brain, spinal cord, and/or protective coverings for these organs.
Retina—
Light-sensitive tissue on the back of the eye that receives images and converts them into nerve impulses to be sent to the brain by way of the optic nerve.
Retinol—
A fat-soluble vitamin found in animal food sources; also known as vitamin A.
Salmonella
A genus of bacteria that causes food poisoning, acute gastrointestinal inflammation, typhoid fever, and septicemia.
Spina bifida—
A birth defect in which the neural tube that develops into the spinal vertebrae does not completely close, leaving parts of the spinal cord exposed.
Toxoplasmosis—
A disease characterized by flu-like symptoms and caused by the parasite Toxoplasma gondii. Infection early in pregnancy may cause miscarriage. Infection late in pregnancy can infect the fetus, even if the mother shows no symptoms of infection. People generally become infected by coming into contact with cat feces that contains the parasite or by consuming food or drink contaminated with the parasite.

Apart from folic acid and vitamin D, other vitamin and mineral supplements often are unnecessary during pregnancy. If dietary intakes are inadequate, a low-dose multivitamin and mineral supplement may be taken with physician approval. High-dose supplements should be avoided, particularly those that contain vitamin A (retinol). A number of specially formulated vitamin and mineral supplements, known as prenatal vitamins, are available for pregnant women and women planning to conceive. Pregnant women and women who wish to become pregnant should consult their doctors as early in pregnancy as possible before taking any supplements, herbs, or medications.

Precautions

Indigestion, heartburn, and intestinal discomfort are common conditions during pregnancy, especially in the third trimester when the baby takes up more space. Women usually learn by experience which foods to avoid, and this avoidance is unlikely to lead to any nutritional problems unless it involves foods that are a major source of important nutrients (e.g., all meat or dairy products). Eating small meals and avoiding fatty and spicy foods may help alleviate digestive symptoms.

Women who are experiencing constipation or hemorrhoids should increase the amount of fiber in their diet by eating more whole grains. Adequate fluid intake is also important, along with gentle exercise.

The causes of nausea and vomiting in pregnancy are not fully understood, although it has been suggested that changes in hormone levels or a heightened sense of smell may be involved. The experiences of individual women are highly variable and can differ with successive pregnancies. Some women find that eating small, frequent meals can help to reduce nausea. Fruits and grains (e.g., bananas, toast, cereal, dried fruit) together with plenty of fluids are often the best choices.

Infants whose parents have a history of allergies are more likely to develop allergies themselves. Some researchers have suggested that by avoiding certain foods during pregnancy, breastfeeding mothers may help to prevent allergies in their infants, but there is little evidence to support this. Other scientists have suggested that exposure to these foods can actually help a baby develop tolerance to them. If there is a strong family history of allergic disease (i.e., if either parent or a previous child has suffered from hayfever, asthma, eczema, or another allergy), some women may wish to avoid peanuts or foods containing peanuts during pregnancy and while breastfeeding in order to reduce the risk of the infant developing a peanut allergy; research has yet to prove whether or not this technique is successful.

Risks

Vitamin A

A high vitamin A (retinol) intake during pregnancy can cause birth defects. Pregnant women should avoid liver and liver products, such as pate, as these foods can contain high concentrations of vitamin A. Foods fortified with vitamin A should also be avoided, as should supplements containing vitamin A (in the form of retinol), high-dose multivitamins, and cod liver oil supplements. Concerns about vitamin A consumption should be addressed to a physician or registered dietitian.

Alcohol

Drinking alcohol can increase the risk of birth defects and low birth weight. Excessive alcohol intake can result in fetal alcohol syndrome, a serious condition that can permanently affect the physical and mental development of the child. Pregnant women should abstain from alcoholic drinks during pregnancy to avoid complications.

Caffeine

Pregnant women should not consume excessive amounts of caffeine, as levels above about 300 mg/day have been linked with low birth weight and miscarriage. Caffeine occurs in a range of food and drinks such as coffee, tea, soft drinks, and chocolate. In the United Kingdom, the Food Standards Agency recommends that pregnant women should not drink more than the equivalent of around four cups of coffee a day. Many physicians in the United States recommend limiting caffeine to the equivalent of one or two cups of coffee daily.

Foodborne illness

Pregnant women should take care to follow food hygiene guidelines when handling foods, especially raw meat. It is sensible to avoid foods that increase the risk of foodborne infections such as listeriosis (contracted from unpasteurized milk, cheese made from unpasteurized milk, or mold ripened-cheeses, which are usually soft or blue cheeses) or salmonella poisoning (most commonly contracted from undercooked or raw chicken or raw eggs). It is also important to wash raw vegetables thoroughly, as eating soil may cause toxoplasmosis.

Important foods to avoid to minimize the risk of foodborne illness during pregnancy include:

Contaminants in fish

Fish is a good source of protein, vitamins, and minerals. In particular, oil-rich fish (e.g., mackerel, salmon, kippers, herrings, trout, sardines, and fresh tuna) contain the long chain omega-3 fatty acids that are essential to brain and eye development in the fetus. However, fish can contain certain contaminants, namely mercury, dioxins, and polychlorinated biphenyls (PCBs). There is concern about the consequences of prenatal exposure to these toxic chemicals on brain and nervous system development.

QUESTIONS TO ASK YOUR DOCTOR

High concentrations of methylmercury have been found in large, predatory fish such as sharks, marlin, and swordfish. These fish should be avoided during pregnancy and breastfeeding. In the United States, this also includes king mackerel and tilefish. Some samples of these have been found to have higher levels than other fish species. In the United Kingdom, pregnant women and women who may become pregnant are advised to restrict their weekly intake to two 140 g portions of fresh tuna or four 140 g portions of canned tuna. The Academy of Nutrition and Dietetics recommends a maximum of six ounces of albacore (white) tuna a week during pregnancy and that women restrict total fish consumption to 12 ounces of cooked fish per week, avoiding those listed above.

Oily fish can contain PCBs and dioxins. Because of the benefits of oily fish consumption, pregnant women are advised to follow the general advice for fish consumption and consume at least two portions of fish per week, one of which should be oily, with no more than two portions of oily fish per week. This advice also applies to women who might become pregnant and women who are breastfeeding.

Resources

BOOKS

Ward, Elizabeth M., and the Academy of Nutrition and Dietetics. Expect the Best: Your Guide to Healthy Eating Before, During, and After Pregnancy. 2nd ed. Nashville, TN: Turner, 2017.

PERIODICALS

Thangaratinam, S., et al. “Effects of Interventions in Pregnancy on Maternal Weight and Obstetric Outcomes: Meta-Analysis of Randomised Evidence.” British Medical Journal 344 (May 2012). http://dx.doi.org/10.1136/bmj.e2088 (accessed April 16, 2018).

WEBSITES

March of Dimes Foundation. “Eating Healthy during Pregnancy.” http://www.marchofdimes.com/pregnancy/nutrition_indepth.html (accessed April 16, 2018).

Mayo Clinic staff. “Pregnancy Diet: Focus on These Essential Nutrients.” MayoClinic.com . http://www.mayoclinic.com/health/pregnancy-nutrition/PR00110 (accessed April 16, 2018).

McGrane, Mary, et al. “Maternal Intake of Seafood Omega-3 Fatty Acids and Infant Health: A Review of the Evidence.” Nutrition Insights 46 (February 2012). U.S. Department of Agriculture, Center for Nutrition Policy and Promotion. https://www.cnpp.usda.gov/sites/default/files/nutrition_insights…/Insight46.pdf (accessed April 16, 2018).

Rasmussen, K. M., and A. L. Yaktine, eds. Weight Gain during Pregnancy: Reexamining the Guidelines. Institute of Medicine and National Research Council Committee to Reexamine IOM Pregnancy Weight Guidelines. Washington, DC: National Academies Press, 2009.

2015 Dietary Guidelines Advisory Committee. Scientific Report of the 2015 Dietary Guidelines Advisory Committee. U.S. Department of Health and Human Services, Office of Disease Prevention and Health Promotion, February 2015. Health.gov . https://health.gov/dietaryguidelines/2015-scientific-report/ (accessed April 16, 2018).

U.S. Department of Agriculture. “Moms/Moms-To-Be.” ChooseMyPlate.gov . http://www.choosemyplate.gov/pregnancy-breastfeeding.html (accessed April 16, 2018).

ORGANIZATIONS

Academy of Nutrition and Dietetics, 120 South Riverside Plz., Ste. 2000, Chicago, IL, 60606-6995, (312) 899-0040, (800) 877-1600, amacmunn@eatright.org, http://www.eatright.org .

British Nutrition Foundation, High Holborn House, 52-54 High Holborn, London, United Kingdom, WC1V 6RQ, +44 20 7404 6504, Fax: +44 20 7404 6747, postbox@nutrition.org.uk, http://www.nutrition.org.uk .

Center for Nutrition Policy and Promotion, 3101 Park Center Dr., 10th Fl., Alexandria, VA, 22302-1594, (703) 305-7600, Fax: (703) 305-3300, Support@cnpp.usda.-gov, http://www.cnpp.usda.gov .

National Women's Health Network, 1413 K St. NW, 4th fl., Washington, DC, 20005, (202) 682-2640, Fax: (202) 682-2646, healthquestions@whn.org, http://www.nwhn.org .

Sara Stanner, MSc, PHNutr
Revised by Tish Davidson, AM

  This information is not a tool for self-diagnosis or a substitute for professional care.