Q: I plan to try to have a baby next year. Why does my OB-GYN want me to take folic acid even before I’m pregnant?

A: Your doctor is trying to reduce the risk of your baby having a neural tube defect (NTD). The neural tube is a thin column of cells that develop to form the brain and the spinal cord.

A defect in this tube can prevent the baby’s brain from developing or result in an exposed spinal cord at birth. Worldwide, approximately 300,000 infants are born with an NTD every year.

Mothers with lower levels of vitamin B, including folate, carry a greater risk of having a baby with neural tube defects than women with higher levels of folate.

For these reasons, physicians recommend that all women who are planning a pregnancy or are capable of becoming pregnant should take 400 micrograms of folic acid daily.

Begin taking folic acid at least one month before you conceive and continue through the first 12 weeks of pregnancy. It has been estimated that 16 to 58 percent of NTDs could be prevented by folic acid supplementation.

Other risk factors for NTDs include: a history of a previous pregnancy with NTDs, having an NTD yourself, having a partner with an NTD and having a partner who already has a child with an NTD.

If you have a higher risk of NTDs, your doctor will recommend that you take 4 mg (4,000 micrograms) of folic acid daily. Start supplements three months before you conceive and continue until the 12th week of pregnancy. This might reduce your risk by as much as 70 percent.

Folic acid supplements cannot, however, prevent all neural tube defects. Some types of NTDs are resistant to folic acid and can cause out-of-control glucose (blood sugar) levels in your first trimester of pregnancy, hyperthermia, maternal obesity and certain genetic disorders.

If you have diabetes, folic acid supplements might decrease your risk of NTDs but will not eliminate it. That’s why it is important that you manage your blood sugar levels even before you get pregnant.

Obese women also might not get the full benefit of taking folic acid before pregnancy. Studies have found that an obese woman’s risk of having a baby with neural tube defects is not always decreased by supplementation.

If you are considering pregnancy, talk to your OB-GYN about your potential risk for NTDs. Now is the time to plan ahead for a healthy baby.

Joanne Price Williamson, M.D., is an obstetrician-gynecologist in practice at Provident OB/GYN Associates in Okatie.