Pregnancy outcome following first-trimester exposure to zopiclone: a prospective controlled cohort study.

Abstract

Zopiclone, a cyclopyrrolone derivative, is a short-acting hypnotic. To date, no published data exist regarding human pregnancy experience with zopiclone. The purpose of this study was to compare pregnancy outcome following first-trimester exposure to zopiclone with that of a matched control group of women, who were counseled for nonteratogenic exposure. The Motherisk Program, the Toronto Teratogen Information Service, prospectively collected and followed up 40 women exposed to zopiclone during pregnancy. Pregnancy outcome was compared with that of a matched control group of women, who were counseled for nonteratogenic exposure. There was no increase in the rate of major malformations (0 of 31 [0%] for zopiclone vs. 1 of 37 [2.7%] for nonteratogenic controls; p = 1). Our study, which is the first cohort on zopiclone use during embryogenesis, albeit small, suggests that zopiclone does not appear to be a major human teratogen. Larger studies are needed to establish its safety during pregnancy.