Periconceptional multivitamin use reduces the risk of preeclampsia.

The objective was to assess the independent effect of regular periconceptional multivitamin use on the risk of preeclampsia. Pregnant women (n=1,835) enrolled in the Pregnancy Exposures and Preeclampsia Prevention Study (Pittsburgh, Pennsylvania, 1997-2001) at less than 16 weeks' gestation were asked whether they regularly used multivitamins or prenatal vitamins in the past 6 months. Women were classified as users or nonusers. The unadjusted prevalence of preeclampsia was 4.4% in nonusers and 3.8% in users. After adjustment for race/ethnicity, marital status, parity, prepregnancy physical activity, and income in a multiple logistic regression model, regular use of multivitamins was associated with a 45% reduction in preeclampsia risk compared with nonuse (odds ratio (OR)=0.55, 95% confidence interval (CI): 0.32, 0.95). Prepregnancy overweight modified this effect. After confounder adjustment, lean multivitamin users had a 71% reduction in preeclampsia risk compared with lean nonusers (OR=0.29, 95% CI: 0.12, 0.65). In contrast, there was no relation between multivitamin use and preeclampsia among overweight women (OR=1.08, 95% CI: 0.52, 2.25). A sensitivity analysis for unmeasured confounding by fruit and vegetable intake supported these conclusions. If confirmed by others, these results suggest that regular use of a multivitamin supplement in the periconceptional period may help to prevent preeclampsia, particularly among lean women.