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

Objective: To investigate the effect of folic acid (FA) supplementation on the risks of preterm delivery (PTD) and small for gestational age births (SGA). Data sources: Cohort studies were identified from MEDLINE, EMBASE, the Cochrane Library, CINAHL, and CBM from inception to January 2015. Participants and included studies: Healthy women who want to get pregnancy or being pregnant. Main outcome measures: PTD and SGA. Results: The association of FA and PTD was significant when supplement initiated after pregnancy (RR= 0.68, 95%Cl, 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). Conclusion: Folic acid supplementation is associated with a significant reduction on the risk of PTD when initiated after conception. It can also protect fetus from SGA.(C) 2016 Elsevier Inc. All rights reserved.