Women who take folic acid supplements for at least one year before they become pregnant may cut their risk of having a premature baby by half, according to research published this week in the online journal, PLOS Medicine.

The study links pre-conceptional folate supplementation of at least one year to reduced early premature delivery rates of 50 to 70 percent, regardless of age, race or other factors. Of particular note is the drop in very early premature births, those babies who are at the greatest risk of complications such as cerebral palsy, mental retardation, chronic lung disease, and blindness.

The study is an observational analysis based on the self-reporting of folate supplementation by 38,033 participants in an earlier trial sponsored by the National Institutes of Health (NIH.)  The current study only examined singleton pregnancies and excluded pregnancies with medical or obstetrical complications such as preeclampsia, chronic hypertension, or other abnormalities.

"The NIH provided highly accurate evidence of gestational age which enabled us to determine that folate supplementation for at least one year is linked to a 70 percent decrease in very early preterm deliveries (20 to 28 weeks gestation) and up to a 50 percent reduction in early preterm deliveries of 28 to 32 weeks," said Radek Bukowski, M.D., Ph.D., assistant professor, Obstetrics and Gynecology, at the University of Texas Medical Branch at Galveston, the lead study author.

"We already know that folic acid supplementation beginning before pregnancy and continuing into the first trimester helps prevent serious birth defects of the brain and spinal cord, such as spina bifida," said Alan R. Fleischman, M.D., senior vice president and medical director of the March of Dimes. "Dr. Bukowski's research makes us optimistic that taking folic acid for at least one year before pregnancy also may greatly reduce the risk of premature birth and reinforces our message that every woman of childbearing age should consume 400 micrograms of folic acid daily."

The March of Dimes honored Dr. Bukowski's study in January 2008 during the annual meeting of the Society for Maternal Fetal Medicine.  "Preconceptional Folate Supplementation and the Risk of Spontaneous Preterm Birth: A Cohort Study " by Bukowki, is available online.