The fetal safety of cetirizine: an observational cohort study and meta-analysis.

Cetirizine, a second-generation antihistamine, is an active metabolite of hydroxyzine used in the treatment of allergies, but the data on fetal safety are inconclusive. Pregnant women who were counselled by the 'Motherisk Program' regarding cetirizine exposure were enrolled in a cohort study and compared with pregnant women counselled for non-teratogenic exposures. The objective was to measure the rate of adverse pregnancy outcomes. Subsequently, we also conducted a meta-analysis of cohort studies that examined the pregnancy outcomes of women exposed to hydroxyzine or cetirizine during pregnancy. In the cohort study, there were no significant differences in the rates of major malformations between the cetirizine exposed and comparison group. In the meta-analysis, cetirizine was not associated with increased teratogenic risk. In contrast, a meta-analysis of cetirizine and hydroxyzine studies showed a marginal association with major malformations. Cetirizine is not associated with a clinically important increase in risk of adverse fetal outcomes.