Grand Rounds

Does Folic Acid Decrease Preeclampsia Rates in Those at Risk?

BACKGROUND AND PURPOSE:

Previous studies have suggested that high dose folic acid may prevent preeclampsia in women at higher risk
Wen et al. (BMJ, 2018) assessed the efficacy of high dose folic acid supplementation for prevention of preeclampsia in women with at least one risk factor

Randomized, phase III, double blinded international, multicenter clinical trial (RCT)
Participants: At least one of the following risk factors
- Pre-existing hypertension
- Prepregnancy diabetes (type 1 or 2)
- Twin pregnancy
- Pre-eclampsia in previous pregnancy
- Body mass index ≥35
Women received either
- Daily high dose 4 mg folic acid (four 1.0 mg oral tablets) starting between 8 and 16 weeks of gestation and ending at delivery
- Matched placebo
Primary outcome
- Preeclampsia, defined as hypertension presenting after 20 weeks’ gestation with major proteinuria or HELLP syndrome
Secondary outcomes
- Additional obstetrical outcomes, including severe preeclampsia and neonatal outcomes
Clinical significance was defined as a 30% reduction in preeclampsia when taking folic acid
80% power, two sided type 1 error 0.05

1,144 folic acid group | 1,157 placebo group
- 2,301 were included in the intention to treat analyses
Preeclampsia occurred in
- Folic acid group: 14.8% women
- Placebo group: 13.5%
- Relative risk (RR) 1.10; 95% CI, 0.90-1.34 (P=0.37)
There was no evidence of differences between the groups for any other adverse maternal or neonatal outcomes

Folic acid supplementation with 4.0 mg/day beyond the first trimester does not prevent preeclampsia in women at high risk for this condition
The researchers have received additional funding to follow up participants in this study and determine long term effects of folic acid on maternal and child health

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