Is There a Reason to Supplement with Folic Acid Prior to Conception?

Births that take place prior to 37 weeks of gestation have been associated with developmental disabilities and decreased survival. It is also known that women who have low plasma folate concentrations during pregnancy are at higher risk of giving birth prematurely.

A May 2009 article published in the PLoS Medicine journal reports that women who consumed folic acid supplements for a year or more before conceiving experienced a significantly lower risk of preterm births.

Natural length of pregnancy was defined as gestational age at delivery in pregnancies with no medical or obstetrical complications that would make early delivery necessary. Spontaneous preterm birth was defined as duration of pregnancy between 20 and 37 weeks without those complications.

The risk of preterm delivery was directly related to the duration of folic supplementation. Compared to women who did not supplement, women who supplemented for at least one year prior to conception experienced a 70 percent lower risk of premature delivery between the 20 and 28 week of gestation, and a 50 percent decrease between the 28 and 32 week.

Pre-conception folic acid supplementation is associated with a 50-70 percent reduction in the incidence of early spontaneous preterm birth, and the risk of preterm birth is decreased the most in women who supplement the longest before conception.

PLoS Med 6(5):2009