While it's common to say that a pregnant woman is "eating for two," in reality, a developing baby requires only a small number of calories--about an extra 200 to 300 calories per day beyond a woman's normal nutritional needs. Pregnant women benefit from healthy, balanced diets, and the components of the food they eat are absorbed and passed along to the baby. Because the placenta can transmit harmful chemicals and some infections as well as food, however, there are foods that pregnant women should avoid to ensure optimal fetal health.
Nitrate-Cured Meats
Some meats, particularly hot dogs, bacon and some ham products, are preserved with chemicals called nitrates. While the nitrates help prevent colonization of the meat by bacteria, they can also cross over the placenta and negatively impact fetal health, explains Dr. Miriam Stoppard in her book, "Conception, Pregnancy and Birth." Animal studies have shown, explains Dr. Stoppard, that nitrates can cross the placenta and cause fetal miscarriage or spontaneous abortion. To be safe, pregnant women should avoid all hot dogs and bacon and should read ingredients on ham products carefully.
Deli Meat
Because delis often use meat that has been sliced and left at or near room temperature for some time, there is increased possibility of contamination of that meat by certain bacterial species. While meat itself isn't a problem during pregnancy--and in fact is a source of valuable protein--meat that might be contaminated with bacteria poses a risk to pregnant women and their fetuses. Explain Drs. Michael Roizen and Mehmet Oz in their book, "You: Having A Baby," deli meat may be contaminated with listeria, which isn't normally a problem for adults. Pregnant women have reduced immune function, however, putting them at increased risk for infection, and bacteria can cross the placenta.
Certain Fish
While fish are an excellent component of a healthy diet during pregnancy, since they contain protein as well as healthy fats, certain fish are of concern. In particular, explain Heidi Murkoff and Sharon Mazel in their book, "What To Expect When You're Expecting," large predator fish can have very high levels of mercury in their bodies. Such fish, including shark, mackerel and swordfish, pose a risk to the developing fetus, as mercury is a neurotoxin and impacts brain development. Pregnant women should also avoid eating tuna more than once a week, as it is high in mercury. Tuna contains many beneficial components of diet, however, so it's worth eating occasionally.
References
- "Conception, Pregnancy and Birth"; Miriam Stoppard, M.D.; 2008
- "You: Having A Baby"; Michael Roizen, M.D. and Mehmet Oz, M.D.; 2009
- "What to Expect When You're Expecting"; Heidi Murkoff and Sharon Mazel; 2008
