Effect of folic acid supplementation during pregnancy on gestational hypertension/preeclampsia: A systematic review and meta-analysis.
OBJECTIVE
To evaluate the effect of folic acid supplementation during pregnancy on the risk of gestational hypertension/preeclampsia.


METHODS
A systematic review and meta-analysis were conducted. Medline, Embase, Scopus, and the Web of Science were searched from inception to December 2014.


RESULTS
Out of 1224 potentially relevant studies, 13 studies met our inclusion criteria (2 randomized controlled trials (RCTs), 10 cohort studies, and 1 case-control study). The pooled relative risk (RR) and 95% confidence interval (CI) of the two RCTs were 0.62 (0.45-0.87) in the trial arm as compared with the placebo arm. The pooled RR was 0.92 (95% CI: 0.79-1.08) for nine cohort studies with available data on folic acid supplementation in pregnancy and gestational hypertension/preeclampsia. Pooled RR was 0.88 (95% CI: 0.76-1.02) for eight cohort studies with available data on folic acid supplementation and preeclampsia.


CONCLUSIONS
Whether folic acid supplementation in pregnancy can prevent the occurrence of gestational hypertension/preeclampsia remains uncertain.
a Department of Obstetrics , Xinhua Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai , China.|b Department of Obstetrics and Gynecology, Faculty of Medicine , OMNI Research Group, University of Ottawa , Ottawa , Ontario , Canada.|c Clinical Epidemiology Program , Ottawa Hospital Research Institute , Ottawa , Ontario , Canada.
Xiaolin
X
Hua
b Department of Obstetrics and Gynecology, Faculty of Medicine , OMNI Research Group, University of Ottawa , Ottawa , Ontario , Canada.|c Clinical Epidemiology Program , Ottawa Hospital Research Institute , Ottawa , Ontario , Canada.|d Department of Obstetrics and Gynecology , Beijing Friendship Hospital, Capital Medical University , Beijing , China.
Jiewen
J
Zhang
b Department of Obstetrics and Gynecology, Faculty of Medicine , OMNI Research Group, University of Ottawa , Ottawa , Ontario , Canada.|c Clinical Epidemiology Program , Ottawa Hospital Research Institute , Ottawa , Ontario , Canada.
Yanfang
Y
Guo
b Department of Obstetrics and Gynecology, Faculty of Medicine , OMNI Research Group, University of Ottawa , Ottawa , Ontario , Canada.|c Clinical Epidemiology Program , Ottawa Hospital Research Institute , Ottawa , Ontario , Canada.|e School of Public Health , Central South University , Changsha , China.
Minxue
M
Shen
b Department of Obstetrics and Gynecology, Faculty of Medicine , OMNI Research Group, University of Ottawa , Ottawa , Ontario , Canada.|c Clinical Epidemiology Program , Ottawa Hospital Research Institute , Ottawa , Ontario , Canada.
Laura
L
Gaudet
f Canadian Agency for Drugs and Technologies in Health , Ottawa , Ontario , Canada.
Ghayath
G
Janoudi
b Department of Obstetrics and Gynecology, Faculty of Medicine , OMNI Research Group, University of Ottawa , Ottawa , Ontario , Canada.|c Clinical Epidemiology Program , Ottawa Hospital Research Institute , Ottawa , Ontario , Canada.|g School of Epidemiology, Public Health, and Preventive Medicine , University of Ottawa Faculty of Medicine , Ottawa , Ontario , Canada.
Mark
M
Walker
b Department of Obstetrics and Gynecology, Faculty of Medicine , OMNI Research Group, University of Ottawa , Ottawa , Ontario , Canada.|c Clinical Epidemiology Program , Ottawa Hospital Research Institute , Ottawa , Ontario , Canada.|e School of Public Health , Central South University , Changsha , China.|g School of Epidemiology, Public Health, and Preventive Medicine , University of Ottawa Faculty of Medicine , Ottawa , Ontario , Canada.
Shi Wu
SW
Wen
D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000627:therapeutic use*; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000517:prevention & control*; D011247:Pregnancy; D016896:Treatment Outcome
D005492:Folic Acid
Folic acid; gestational hypertension; preeclampsia; supplementation