Taking folic acid during pregnancy:Don't leave it too late

Debbie Kennedy, MD; Anne Pastuszak, MSC; Gideon Koren, MD, FRCPC

December, 1997

The following is written simply and is aimed at nonmedical people. We suggest you disseminate this information to your patients who are planning pregnancy.

Recent medical research has shown that taking folic acid supplements during pregnancy could reduce the risk of neural tube defects (NTDs) in babies. Two disorders account for most NTDs: the first, spina bifida, results from failure of the spine to develop normally; the second, anencephaly, results from abnormal skull and brain development.

Every baby has a small chance of having a birth defect; birth defects occur in about three of every 100 liveborn infants. Neural tube defects account for some of these defects, occurring in two to four of every 1000 babies born in Canada.

What?
Folic acid (also called folate or folacin) is a B-group vitamin. Foods rich in folic acid include grains, green vegetables (spinach, broccoli), meat (liver), and legumes (lentils and kidney beans). Although folic acid is present in these foods, it is often difficult to get the daily requirement of folic acid from diet alone.

When?
Because NTDs occur 25 to 29 days after conception, before many women even realize they are pregnant, it is important for women to begin taking folic acid supplements before conception (ideally, when birth control measures are discontinued). Since a woman's folic acid requirements increase during pregnancy and breastfeeding, it might be beneficial for her to continue taking folic acid supplements throughout pregnancy, even though crucial development of the spine and brain is complete 5 weeks after conception.

How much?
Most healthy women should supplement their diets with 0.4 mg of folic acid daily. Women who have diabetes or epilepsy, women with a family history of NTDs (in a sibling, parent, cousin), and women who have had previous liveborn or stillborn infants with NTDs should supplement their diet with 5 mg of folic acid daily. Women should contact their physicians for confirmation of the correct dosage.

Tests
Tests available to all pregnant women can detect NTDs during the second trimester of pregnancy.

• A blood test can measure the level of -fetoprotein in a mother's blood. This test is usually performed between 16 and 18 weeks of pregnancy.
• Ultrasound examination of the baby's head and spine is usually done between 17 and 20 weeks of pregnancy.

References