When taken before you conceive and throughout your pregnancy, folic acid (also known as vitamin B9) has been shown to drastically decrease the risk of neural tube defects like spina bifida and anencephaly. In fact, doctors and the CDC think so highly of this vitamin that they recommend every woman of child-bearing age (even if you're not currently in baby-making mode) takes 400 micrograms of folic acid every day, just in case. Since baby's neural tube closes around days 49 to 56—and that's often the time women first realize they're pregnant—you'll be covered if you've already been taking folic acid on a daily basis. Once you get pregnant, the suggested daily intake jumps to 600 to 800 micrograms. If you have a family history of neural tube defects, you should get even more (usually about 10 times as much), so let your doctor know and she can help determine the correct amount you'll need.
Find this wonder-acid in whole grains, leafy greens, citrus fruits and some legumes. Since the US government has hopped on the folic acid bandwagon, the vitamin is now added to nearly all breads, cereal, pasta, rice and flour. (Finally, a good reason to eat carbs!) But even if you're eating many of these folic-acid-rich foods you can (and should) up your folic acid intake even more with a supplement. Most women don’t get nearly enough of this vitamin, and since it’s water-soluble, you’ll just pee out whatever you don’t need.