Pregnancy Outcome Following First-Trimester Exposure To Zopiclone: A Prospective Controlled Cohort Study

BACKGROUND & AIM: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.