Is captopril safe for women who are pregnant or breastfeeding?

No. Ace inhibitors are not advised for use in treatment of hypertension during pregnancy due to their association with significant birth defects. Alternative medications that are safe in pregnancy should be used for treatment of preexisting hypertension during pregnancy. All treatment plans should be individualized between a woman, her ob/gyn, and possibly cardiologist and/or perinatologist.
Yes, in breastfeeding. Pregnancy risk is for medications is not the same as breastfeeding risk. According to lactmed, a great source of information for breastfeeding mothers and practitioners alike, Captopril is considered compatible with nursing. Because of the low levels of Captopril in breastmilk, amounts ingested by the infant are small and would not be expected to cause any adverse effects in breastfed infants.