A healthy diet that provides all the necessary nutrients for the developing fetus increases the chances of a healthy pregnancy. For this reason, it is best to avoid certain diets in pregnancy. In particular, high-fat diets, some vegetarian diets, and weight loss diets should generally be avoided by pregnant women. A healthy diet also means limiting sugar intake. Many women also choose to start eating a healthy diet in the stage prior to conception to maximize their chances of delivering a healthy baby. In general, a healthy diet is the same for both pregnant women and non-pregnant women, with a few special exceptions that will be discussed below.Evidence about whether consumption of caffeine in pregnancy is detrimental has been inconclusive. However, it is known that the fetus metabolizes caffeine very slowly, so maternal consumption of caffeine results in a prolonged exposure for the fetus. Consumption of typical levels of caffeine has not been associated with any adverse pregnancy outcomes, yet individual studies have shown that caffeine can lead to changes in fetal arousal and heart rate. According to many experts, including the American Academy of Nutrition and Dietetics, caffeine intake in pregnant women should be limited to 200 mg per day (equivalent to one 12 oz. cup).Women who are planning to become pregnant are advised to take folic acid supplements to reduce the likelihood of neural tube defects in the fetus. The neural tube closes early in pregnancy (18 to 26 days after conception) so supplementation with folic acid is most critical during the early days of pregnancy. Often, supplementation after the diagnosis of pregnancy is too late to reduce the risk of neural tube defects. Vitamins containing 400 to 800 mcg of folic acid, taken daily, are recommended.Due to the presence of certain environmental toxins (such as mercury), the kinds and amount of fish (and shellfish) that are eaten during pregnancy should be regulated. The US FDA has issued guidance for pregnant women and those planning a pregnancy regarding the types and amount of fish that should be eaten.
In general, 2-3 servings of fish that are low in mercury are recommended per week.
Seafood that is lower in mercury includes salmon, shrimp, Pollock, tuna (light canned), tilapia, catfish, and cod.
Tilefish from the Gulf of Mexico, shark, swordfish, and king mackerel are typically high in mercury and should be avoided.
Pregnant women should not consume raw fish.
Megavitamins may not be safe for pregnant women, since excessive doses of vitamins can be harmful and their effects on the fetus have not been fully studied. Megadoses of vitamin A in early pregnancy have been linked to birth defects. Women planning pregnancy and who are pregnant also are advised not to consume nonessential dietary supplements or herbal preparations, since their effects on the developing fetus are unknown. The safest choice for women planning a pregnancy is to take a prenatal vitamin supplement that contains folic acid and iron.Pregnant women also should try to avoid unpasteurized milk, soft cheeses, deli and luncheon meats, and undercooked or raw animal foods. This is due to the risk of exposure to Listeria monocytogenes, common bacteria that can cause miscarriages and other problems. Fruits and vegetables should be washed well before consumption.