Animal studies during organogenesis have failed to reveal evidence of teratogenicity. Reduced fetal weight and increased incidences of skeletal variations and/or delayed ossification have been reported at mid to high doses. Increased postimplantation loss, decreased postnatal pup weights and survival, and increased pup startle response were reported to occur at all doses when administered during pregnancy and lactation. There are no controlled data in human pregnancy.

Animal studies have also reported decreased fertility thought to be due to effects in both males and females. No females became pregnant when both males and females were treated with the highest doses. Other effects have been reported to include abnormal estrus cycles, decreases in sperm number and motility, and increases in morphologically abnormal sperm. The no-effect dose for adverse effects on fertility is reported at 16 times the maximum recommended human dose (on a mg/m2 basis).

US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D, and X are being phased out.

This drug should be used during pregnancy only if the potential benefit outweighs the risk to the fetus.

US FDA pregnancy category: Not assigned.

Risk summary: There are insufficient data available on use of this drug in pregnant women to identify of drug-related risks (e.g., adverse maternal/fetal outcomes, major birth defects, miscarriage).

Comment: Patients who are pregnant or may become pregnant should be apprised of the potential harm to the fetus.

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A decision should be made to discontinue breastfeeding or discontinue the drug, taking into account the importance of the drug to the mother.

Excreted into human milk: Unknown (parent drug); Yes (zopiclone [racemate])
Excreted into animal milk: Unknown (parent drug)

Comments:
-The effects in the nursing infant are unknown.
-Some experts recommend the use of alternative hypnotic agents (e.g., zaleplon, zolpidem) when nursing a newborn or preterm infant.

Using the data from a study of 12 nursing mothers who were given a single, 7.5 mg zopiclone dose orally, an exclusively breastfed infant would receive an estimated 15 mcg/kg daily or about 1.2% to 1.4% of the maternal weight-adjusted dosage. Peak levels of 34 mcg/L were observed approximately 2.4 hour after administration.

See references