When it comes to diet during pregnancy, opinions vary from "everything you put in your mouth matters" to "just try to eat healthy."
As usual, the truth probably lies somewhere in between.
"A lot of the pregnancy books, I think, swing too much into telling you every single thing you need to eat, and act as if indiscretions are poisonous, which really isn't true," said Dr. Marjorie Greenfield, chief of obstetrics and gynecology at University Hospitals Case Medical Center.
But there are three things that every woman who's pregnant -- or planning to be -- should know.
Women should start taking a folic acid supplement -- 400 mg every day -- at least three months before they want to become pregnant to minimize the risk of nervous system birth defects, according to the Centers for Disease Control and Prevention.
Eating foods naturally high in folate like leafy greens and beans, and fortified foods like whole grain bread and rice, can help keep moms and babies nourished throughout pregnancy.
For more about vitamins during pregnancy, visit the March of Dimes website.
Mercury can interfere with normal brain development, so women should avoid foods that contain mercury, such as certain types of fish, during pregnancy and leading up to it, Greenfield said.
"People can say, 'I just won't eat any fish during pregnancy,' but unfortunately there are other things in fish that are actually really, really good for the developing brain," Greenfield said.
Avoid fish high in mercury, such as king mackerel, tilefish, swordfish and shark, but keep other types of fish and shellfish, such as cooked shrimp, salmon and tuna, on the table.
Learn more about mercury-containing foods by visiting the FDA website.
As babies grow, so do moms. But gaining too much weight during pregnancy can be risky for both parties.
"Babies can be extra big, labor can be extra hard and gestational diabetes is more likely," Greenfield said. "Plus, it's hard to get the weight off afterwards, and excess weight gain in pregnancy may be contributing to the epidemic of obesity in our country."
But how much weight gain is appropriate depends on the woman and the baby.
"Talk to your doctor or midwife about weight gain, because it depends on your starting weight and eating habits," Greenfield said.
On top of getting enough folic acid, limiting mercury and maintaining a healthy weight, pregnant women should drink six to eight glasses of water a day, avoid alcohol and eat from all five food groups. The CDC recommends six to 11 servings of grain products, three to five servings of vegetables, two to four servings of fruits, four to six servings of milk and milk products, and three to four servings of meat and protein foods every day.