Metopimazine is an anti-emetic drug used to treat nausea and vomiting of pregnancy. However, no animal or clinical data are available regarding its safety in pregnant women. The aim of this study was, therefore, to assess the risk of birth defects and pregnancy loss associated with the use of metopimazine during pregnancy in a population-based cohort study.

The study focused on the EFEMERIS database including the prescription and dispensation of drugs for pregnant women in Haute-Garonne, France, between July 2004 and December 2017. This was an observational, retrospective, comparative study. Pregnancy loss and major birth defects were compared between women exposed to metopimazine during pregnancy and those with no exposure using multivariate logistic regression and Cox proportional risk models.

Among 135,574 pregnant women, 11,402 (8.2%) were exposed to metopimazine during pregnancy, mostly in the first trimester (more than 70% of women). No association was found between major birth defects and exposure to metopimazine in the first trimester of pregnancy (OR_a=[95% CI]=1.06 [0.92–1.23]). Pregnancy loss was negatively associated with metopimazine use during pregnancy (HR_a [95% CI]=0.80 [0.72–0.88]), taking into account major potential confounders. Comparable rates were recorded between women exposed to metopimazine and those unexposed to the drug in terms of prematurity (6.7% vs. 6.4%), low birth weight (6.2% vs. 6.2%) and small for gestational age (1.2% vs. 1.4%).

This study illustrates the wide use of metopimazine during pregnancy in France although no studies on efficacy or safety in pregnant women are available. The results of this study do not indicate any teratogenic effect or an increased risk of pregnancy loss of metopimazine.