Captopril is an antihypertensive agent used in the management of hypertension, the treatment of congestive heart failure and left ventricular dysfunction following myocardial infarction, and diabetic nephropathy. In animal studies, captopril given orally at relatively low doses of 3 mg/kg/day to rabbits late in gestation lengthened the gestation period and increased stillbirths. Sheep given the drug intraveneously late in gestation had no developmental toxicity other than a high incidence of stillborn lambs. The angiotensin-converting enzyme inhibitors (ACEIs) have unique properties in human development. They elicit a significant developmental toxicity termed “ACEI fetopathy” when administered in the second and third trimesters; the 26th week of gestation is said to be critical. The usual laboratory species are inappropriate models for fetopathy in the human, because their renal development is postnatal according to one scientist.