A widely prescribed class of drugs used primarily for treatment of hypertension, called “ACE inhibitors” have been linked to birth defects. The drugs, including captopril and lisinopril, can cause bone abnormalities in the skull, inhibition of growth and kidney damage that can kill the fetus or newborn. According to the American College of Obstetricians and Gynecologists, 30 percent of fetuses are affected. Physicians have been aware for some time about long-understood hazards in the second or third trimester, and the prescribing information for these drugs warns doctors not to prescribe them for pregnant women and to stop them right away if a woman becomes pregnant.
How the drugs might harm the fetus earlier in pregnancy is not understood. Even though captopril came on the market 25 years ago, until now there was hardly any information on the effect of taking ACE inhibitors in the first trimester, and they were thought to be safe.
Dr. Daniel V. Landers, vice chairman of obstetrics and gynecology at the University of Minnesota, said the most important implication of the new study was for women of childbearing age who have high blood pressure and are not yet pregnant. Those planning to become pregnant should not take ACE inhibitors, he said, but doctors and patients should also realize that many pregnancies, close to half, are unplanned. So if the possibility of pregnancy exists, it may be best to avoid the drugs.
Major organs form during the first trimester, and fetuses are quite vulnerable then, Dr. Landers said.
In an editorial in the New England Journal of Medicine, Dr. Friedman said women who have taken ACE inhibitors during the first trimester should have fetal ultrasound scans and echocardiograms at about 18 weeks.
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