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 exper ience with zopiclone. The purpose of this study was to compare pregnancy ou tcome following first-trimester exposure to zopiclone with that of a matche d control group of women, who were counseled for nonteratogenic exposure. M ethods: The Motherisk Program, the Toronto Teratogen Information Service, p rospectively collected and followed up 40 women exposed to zopiclone during pregnancy. Pregnancy outcome was compared with that of a matched control g roup of women, who were counseled for nonteratogenic exposure. Results: The re was no increase in the rate of major malformations (0 of 31 [0%] for zop iclone 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 pregna ncy.