Pre-eclampsia is a condition of high blood pressure during pregnancy that can lead to organ damage, vitamin D deficiency, and dementia. High-dose folic acid supplementation is used for the prevention of pre-eclampsia, but its effectiveness is not well-studies. This study aims to evaluate the efficacy of high-dose folic acid supplementation for the prevention of pre-eclampsia.

This is a randomized, double-blinded international, multicenter, phase-3 trial conducted at 70 obstetrical centers in Argentina, Canada, Australia, UK, and Jamaica. The study included a total of 2,301 pregnant women with at least one risk factor of pre-eclampsia (hypertension, prepregnancy diabetes, twin pregnancy). The participants were randomly assigned in a 1:1 ratio to the folic acid group (n=1,144) or the placebo group (n=1,157) from eight weeks of gestation until delivery.  The primary outcome of the study was pre-eclampsia.

Pre-eclampsia occurred in 169 (14.8%) women in the folic acid group and 156 (13.5%) in the placebo group. There were no significant differences between the groups for adverse maternal or neonatal outcomes.

The research concluded that supplementation with high doses of folic acid in women beyond the first trimester did not decrease the risk of pre-eclampsia in women at a higher risk of the condition.