Multivitamin use and risk of preeclampsia: A systematic review and meta-analysis.

Introduction: Preeclampsia is associated with adverse maternal and neonatal outcomes. It is unclear whether multivitamin use reduces the risk of preeclampsia. This systematic review and meta-analysis aimed to evaluate the association between multivitamin use and the risk of preeclampsia.
Material and Methods: We searched PubMed, Embase and the Cochrane Library from database inception to July 2021. Randomized controlled trials (RCTs), case-control and cohort studies assessing the association between multivitamin use and risk of preeclampsia were eligible. Studies of treatment with a single micronutrient were excluded. Relative risks and 95% confidence intervals (95% CI) were calculated using random-effects models. RoB2, the Newcastle Ottawa Scale and GRADE were used to assess risk of bias and quality of evidence. The protocol was registered in PROSPERO (no. CRD42021214153).
Results: Six studies were included (33 356 women). Only two RCTs were found, both showing a significantly decreased risk of preeclampsia in multivitamin users. These studies were not compatible for meta-analysis due to clinical heterogeneity. A meta-analysis of observational studies using a random-effects model showed an unchanged risk of preeclampsia following multivitamin use (relative risk 0.85, 95% CI 0.69-1.03). The quality of evidence according to GRADE was very low.
Conclusions: Very weak evidence suggests that multivitamin use might reduce the risk of preeclampsia; however, more research is needed. Large RCTs should be prioritized. The results of this review do not allow any final conclusions to be drawn regarding a preventive effect of multivitamin use in relation to preeclampsia.
(© 2022 The Authors. Acta Obstetricia et Gynecologica Scandinavica published by John Wiley & Sons Ltd on behalf of Nordic Federation of Societies of Obstetrics and Gynecology (NFOG).)