Folic acid alone or multivitamin containing folic acid intake during pregnancy and the risk of gestational hypertension and preeclampsia through meta-analyses

OBJECTIVE: The objective of this study was to assess the effect of folic acid and multivitamin use during pregnancy on the risk of developing of hypertensive disorder of pregnancy. METHODS: Two reviewers independently determined all prospective cohort study, retrospective cohort study, large population based cohort study, retrospective secondary analysis, and double blinded, placebo-controlled, randomized clinical trial published using PubMed Medline database, KERIS (Korea Education and Research Information Service), Scopus, and the Cochrane Central Register of controlled trials comparing before conception throughout pregnancy intake oral multivitamin containing folic acid or folic acid alone. Meta-analyses were estimated with odds ratios and 95% confidence intervals (CIs) using random effect analysis according to heterogeneity of studies. RESULTS: Data from six effect sizes from six studies involving 201,661 patients were enrolled. These meta-analyses showed multivitamin containing folic acid or folic acid alone was not significantly effective in reducing gestational hypertension or preeclampsia incidence (odds ratio, 0.91; 95% CI, 0.81 to 1.03) than the placebo. And the difference of effective sizes of preeclampsia and gestational hypertension according to two dependent variables, multivitamin and folic acid were not significant, respectively (point estimate, 0.66; 95% CI, 0.46 to 0.96). CONCLUSION: These meta-analyses demonstrate multivitamin containing folic acid or folic acid alone was not significantly effective in reducing gestational hypertension or preeclampsia incidence.