If you are going to the store for an ovulation predictor kit, add orange juice, beans, liver, and broccoli to your shopping list. These foods are natural sources of folate, an important B vitamin that prevents birth defects. Don't like liver and broccoli? Fortunately, you can ingest vitamin B in a pill form.

In fact, most multivitamins contain folic acid. Since the U.S. Food and Drug Administration approved a plan to add folic acid to food in 1998, it can be found in many cereals, breads, and grains. Other natural sources include spinach, peanuts, asparagus, peas, lentils, and brussels sprouts.

Since most people can't eat enough of these foods to get optimal folate benefits, the March of Dimes and the American Academy of Pediatrics recommend that all women of childbearing age take a daily supplement containing 400 micrograms of folic acid.

According to Dr. Donald R. Mattison, medical director for the March of Dimes, women should make a concerted effort to increase their folic acid intake at least a month before attempting to become pregnant. Timing is key because folic acid can prevent certain birth defects within the first four weeks after conception. "That's often a time before the couple has even recognized that they are pregnant," Mattison says.

Folic acid helps prevent neural tube defects, which cause malformations of the brain and spinal cord, and can lead to conditions like spina bifida (causes paralysis and poor bowel function). Folic acid also may prevent heart defects and Down Syndrome.

Once you are pregnant, your doctor will likely encourage an increase of folic acid. But, check with your doctor before you decide on your own to up your dose. Doubling up on a multivitamin could be dangerous, cautions New York obstetrician Dr. Charles Lockwood.

Even after you bring your new baby home from the hospital, it's a good idea to continue taking folic acid daily, experts say, because half of all pregnancies are unplanned. "It's simple to do," says Mattison. "And well worth it."

For more details about folic acid, visit the March of Dimes at www.modimes.org.