Folic Acid and Multivitamin Supplement Use and Risk of Placental Abruption: A Population-Based Registry Study

Recent studies suggest an association between placental abruption and increased plasma homocysteine levels—a marker of impaired folate status and also an independent risk factor for premature vascular disease. Folic acid and vitamin B12 supplements can lower homocysteine levels, but it is not clear that they lessen the risk of abruption or other adverse pregnancy outcomes. This population-based study examined the association, if any, between multivitamin or folate supplementation and placental abruption in 280,127 singleton births registered in Norway in the years 1999–2004. Odds ratios (ORs) were adjusted for maternal age, marital status, parity, smoking, pregestational diabetes, and chronic hypertension. The use of folic acid and/or multivitamin supplements at any time before or during pregnancy was reported by 44% of women who did not have an abruption and 36% of those who did. The incidence of placental abruption was 0.38% overall, and about half of all abruptions occurred before 37 weeks’ gestation. Multiple logistic regression analysis showed that women who took folic acid and/or multivitamin supplements before or at any time during pregnancy had a 26% reduction in the risk of placental abruption [adjusted OR = 0.74; 95% confidence interval (CI): 0.65–0.84]. Compared to women who did not take multivitamins or folic acid, women taking only folic acid had an adjusted OR for abruption of 0.81 (95% CI: 0.68–0.98), multivitamin users had an adjusted OR of 0.72 (95% CI: 0.57–0.91), and women taking both folic acid and multivitamin supplements had an adjusted OR of 0.68 (95% CI: 0.56–0.83). The association between vitamin use and placental abruption was slightly stronger for women who smoked while pregnant (OR 0.67; 95% CI: 0.53–0.85) than for those who did not smoke (OR = 0.78; 95% CI: 0.67–0.92). This study, the first large-scale attempt to examine the association of folic acid and multivitamin supplements with placental abruption, suggests that women who use supplements are significantly less likely than nonusers to have placental abruption.