Effect of folic acid supplementation on preterm delivery and small for gestational age births: A systematic review and meta-analysis

- FA supplementation reduces the risk of PTD when initiates after pregnancy.
- No protective effect were found of FA on risk of PTD when initiates before pregnancy.
- FA supplementation initiates before or during pregnancy reduces the risk of SGA.

ObjectiveTo investigate the effect of folic acid (FA) supplementation on the risks of preterm delivery (PTD) and small for gestational age births (SGA).Data sourcesCohort studies were identified from MEDLINE, EMBASE, the Cochrane Library, CINAHL, and CBM from inception to January 2015.Participants and included studiesHealthy women who want to get pregnancy or being pregnant.Main outcome measuresPTD and SGA.ResultsThe association of FA and PTD was significant when supplement initiated after pregnancy (RR = 0.68, 95%CI, 0.52-0.90), whereas no effect was founded if the initiation time was before conception (RR = 0.89, 95%CI, 0.80-1.01). The results for the association between FA supplementation and SGA showed significant protective effect: initiated before conception (RR = 0.70, 95%CI, 0.57-0.85) and initiated after conception (RR = 0.84, 95%CI, 0.81-0.89).ConclusionFolic acid supplementation is associated with a significant reduction on the risk of PTD when initiated after conception. It can also protect fetus from SGA.