Source: PLoS Medicine, May 2009: doi:10.1371/journal.pmed.1000061.
Research: In a cohort of 34,480 low-risk singleton pregnancies enrolled in a study of aneuploidy risk, pre-conceptional folate supplementation was prospectively recorded in the first trimester of pregnancy. Duration of pregnancy was estimated based on first trimester ultrasound examination. Natural length of pregnancy was defined as gestational age at delivery in pregnancies with no medical or obstetrical complications that may have constituted an indication for delivery. Spontaneous preterm birth was defined as duration of pregnancy between 20 and 37 weeks without those complications. The association between pre-conceptional folate supplementation and the risk of spontaneous preterm birth was evaluated using survival analysis.
Results: Compared to no supplementation, pre-conceptional folate supplementation for 1 year or longer was associated with a 70% decrease in the risk of spontaneous preterm delivery between 20 and 28 weeks. However, pre-conceptional folate supplementation was not significantly associated with the risk of spontaneous preterm birth beyond 32 weeks. Researchers believe pre-conceptional folate supplementation is associated with a 50%–70% reduction in the incidence of early spontaneous preterm birth.