Long-duration high-dose folic acid supplementation ups risk of gestational hypertension

Use of high dose folic acid (FA) supplements from prepregnancy to midpregnancy may contribute to an increased risk of gestational hypertension, a recent study has shown.

The analysis included 4,853 women participating in the Tongji Maternal and Child Health Cohort, among whom 1,1661 (23.9 percent) were diagnosed with gestational hypertension and 161 (3.3 percent) with pre-eclampsia.

In the cohort, 1,172 women used FA daily at ≥400 to <800 µg with short duration, 573 at ≥400 to <800 µg with long duration, 1,504 at ≥800 µg (high dose) with short duration, and 358 at high dose with long duration. The remaining 646 women were nonusers.

On Poisson regression analysis, women who used high-dose FA from prepregnancy through midpregnancy (long duration) had 33-percent higher risk of developing gestational hypertension compared with nonusers (risk ratio [RR], 1.33, 95 percent confidence interval [CI], 1.08–1.65). The association persisted despite adjustments for social-demographic, reproductive, lifestyle factors, family history of hypertension, other supplement use, and gestational weight gain (RR, 1.32, 95 percent CI, 1.06–1.64).

In contrast, FA supplementation had null effect on the risk of pre-eclampsia.

In light of the findings, the researchers advised that women planning or capable of pregnancy avoid high-dose FA supplementation for long duration, which might have important public health implications in the prevention of gestational hypertension.

Additional prospective cohort studies are needed to further investigate the association between FA supplementation and new-onset hypertension in pregnancy, as well as to elucidate the underlying biological mechanisms, they added.