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Most of these foods are safe to eat and should be part of a healthy pregnancy eating plan. However, there are a few foods (including certain fish, some soft cheeses, ready-to-eat meats and raw sprouts) that may pose risks during pregnancy. A pregnant woman should be aware of these risks, so she can choose the safest foods to nourish herself and her baby.
Which fish are unsafe to eat in pregnancy?
Fish provide plenty of protein and some vitamins and are low in fat. Recent studies suggest that fish (especially those containing omega-3 fatty acids) may aid fetal brain development and may reduce the risk of premature delivery (1, 2). For these reasons, many types of fish are healthy choices for pregnant women.
Mercury is a metal that is present naturally in the environment. It can be released into the air through industrial pollution. When mercury settles into bodies of water, bacteria convert it into a more dangerous form (methylmercury) that accumulates in the fatty tissues of fish. Trace amounts of mercury are present in nearly all types of fish. However, large predatory fish, such as swordfish and sharks, build up the most mercury because they feed on other fish and they live longer than smaller fish (so they have more time to accumulate mercury).
Pregnant women should not eat fish that can be high in mercury, like shark, swordfish, king mackerel and tilefish (3). They can eat up to 12 ounces a week of fish that are low in mercury, including shrimp, salmon, pollock, catfish and canned light tuna. Women should eat no more than 6 ounces of albacore (white) tuna, which has more mercury than canned light tuna, in one week (3). Some omega-3 rich fish that are low in mercury include salmon, herring, anchovies, sardines and trout. By following these guidelines, a pregnant woman can obtain the health benefits of eating fish, while reducing her baby’s exposure to mercury. High levels of mercury can harm an unborn baby or a young child’s developing nervous system.
According to the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA), women who are pregnant or planning pregnancy should avoid eating game fish without first checking its safety with their local health department (3). A game fish is any fish caught for sport, such as trout or bass. Most states issue fish advisories warning the public of mercury contamination. This information is also available on the EPA Web site.
Some game fish also may be contaminated by other industrial pollutants, such as PCBs (polychlorinated biphenyls). Some studies suggest that exposure to high levels of PCBs before birth may contribute to learning problems, decreased IQ and reduced birthweight (4).
Pregnant women should make sure all fish they eat is thoroughly cooked to kill any disease-causing bacteria or parasites. Fish should be cooked until it is opaque and flakes easily with a fork, or a food thermometer measures an internal temperature of at least 145 F. A pregnant woman should avoid sushi and other raw fish, especially shellfish (oysters, clams). These can be polluted by raw sewage and can contain harmful microbes that can lead to severe gastrointestinal illness.
What risks do unpasteurized milk, soft cheeses and ready-to-eat meats pose?
Certain soft cheeses, ready-to-eat meats (including packaged luncheon meats and deli meats) and unpasteurized milk (and products made from it) can cause a form of food poisoning called listeriosis. Listeriosis is caused by a bacterium (Listeria monocytogenes) and is especially dangerous during pregnancy.
When a pregnant woman is infected with listeriosis, she may have a miscarriage, premature delivery or stillbirth, or her newborn baby may become seriously ill and may die. Most people do not become ill when they eat Listeria-contaminated foods. However, healthy pregnant women are more likely than other healthy adults to get listeriosis and more likely to become dangerously ill from it.
Listeriosis often starts with a flu-like illness with fever, muscle aches, chills and, sometimes, nausea or diarrhea. However, it can progress to potentially life-threatening meningitis (infection of the membranes covering the brain, with symptoms such as severe headache and stiff neck) and blood infection. A pregnant woman should contact her health care provider if she develops any of these symptoms. A blood test can show if she has listeriosis. If she does, she can be treated with antibiotics that sometimes prevent fetal infections that could result in miscarriage and stillbirth.
A pregnant woman can help protect herself and her baby from listeriosis by following these guidelines from the FDA:(5)
Is it safe to consume raw sprouts and unpasteurized juices?
Raw vegetable sprouts (including alfalfa, clover, radish and mung bean) and fresh unpasteurized fruit and vegetable juices are loaded with vitamins. Unfortunately, they can carry disease-causing bacteria (such as Salmonella and E. coli), making them unsafe choices for pregnant women (5).
In healthy adults, Salmonella and E. coli infections generally cause diarrhea, nausea, abdominal cramping and fever that lasts for several days. Pregnant women can sometimes become seriously ill from these infections. Occasionally, a pregnant woman can pass a Salmonella or E. coli infection on to her fetus, who can develop diarrhea, fever and, less frequently, meningitis after birth.
A pregnant woman should drink only pasteurized juices. The FDA requires that packaged, unpasteurized juices carry a label stating that they are not pasteurized (5).
Is it risky to eat undercooked meat, poultry or eggs during pregnancy?
Lean meats, poultry and eggs are rich in protein and some vitamins and are an important part of a healthy pregnancy eating plan. However, pregnant women should avoid eating raw or undercooked meats, poultry and eggs because they can increase their risk of a number of food-borne illnesses (including listeriosis, E. coli and Campylobacter infections, salmonellosis and toxoplasmosis).
Toxoplasmosis is a parasitic infection that often causes no symptoms or only mild flu-like symptoms. However, if a pregnant woman contracts it, there’s about a 50 percent chance she will pass it on to her unborn baby (6). Some affected babies develop vision and hearing loss, intellectual disabilities, seizures and other problems. When toxoplasmosis is diagnosed during pregnancy, antibiotic treatment often can help reduce the severity of symptoms in the newborn. Besides undercooked meats, another common cause of toxoplasmosis is contact with cat feces. A pregnant woman always should have someone else clean a cat’s litter box.
Pregnant women should use a meat thermometer to make sure that meat and poultry are thoroughly cooked. Recommended temperatures are as follows (5):
Eggs, which can be contaminated with Salmonella, should be cooked until both the yolk and white are firm. Pregnant women should avoid foods made with raw or partially cooked eggs, like egg nog and hollandaise sauce.
Should a pregnant woman eat liver?
There is some concern about consuming liver during pregnancy. Liver is a good source of protein and is rich in certain vitamins and minerals. These include:
However, in the case of vitamin A, liver may contain too much of a good thing.
Some studies suggest that high doses of vitamin A may cause birth defects. According to the Institute of Medicine (IOM), the recommended dietary allowance (RDA) of vitamin A for pregnant women is 2,565 IUs (international units) per day (7). In a 1995 study, women who took more than 10,000 IUs of vitamin A daily (nearly 4 times the amount recommended by the IOM) in the first two months of pregnancy had more than double the risk of having a baby with birth defects (8). Other studies have suggested that doses under 30,000 IUs daily probably do not cause birth defects, but the lowest dose that may cause birth defects is unknown (9).
The body makes its own vitamin A, when needed, from substances such as beta carotene, which is found in yellow and green vegetables. This raw material for the vitamin is completely safe and healthy during pregnancy. However, much of the vitamin A consumed is the preformed vitamin (retinol) which, in excessive amounts, may cause birth defects. Preformed vitamin A is found in many vitamin supplements and some foods, including meats, eggs, dairy products and fortified breakfast cereals.
Liver is the only food that provides very high amounts of vitamin A. For example (7):
A pregnant woman who eats liver regularly may consume enough vitamin A to pose a risk to her baby.
Though it is not proven that eating liver causes birth defects, the safest approach is for pregnant women to minimize their consumption of liver. A pregnant woman also should be sure that her multivitamin or prenatal supplement contains no more than 5,000 IUs of preformed vitamin A. Some prenatal vitamins contain no preformed vitamin A, substituting beta carotene or omitting vitamin A entirely. She should not take any vitamin A supplements beyond that amount (10).
What safe food-handling practices can help prevent food poisoning?
Everyone should be careful to avoid contamination when handling and preparing food. This is especially important for pregnant women. The FDA recommends the following (5):