A popular class of blood pressure medicines thought to be safe in the first trimester of pregnancy appears to cause serious birth defects in about 7 percent of babies whose mothers took them, a new study has found.
ACE inhibitors already carry a warning that pregnant women should not use them in the last two trimesters because they can cause kidney damage to the fetus. The number of women taking them early in pregnancy is unknown but probably small, the study suggests.
ACE inhibitors are the second-most commonly prescribed class of pharmaceuticals in the United States, with 149 million prescriptions dispensed last year.
“It would be important for a pregnant woman and her health-care provider to be aware of this, so they can identify an alternative medicine to treat her hypertension,” said William Cooper, a pediatrician at Vanderbilt Children’s Hospital who headed the study, published in today’s New England Journal of Medicine.
Exposure to ACE inhibitors early in pregnancy nearly tripled the risk of birth defects, the study showed.
“We all believe that we want to see more data. But this is important enough and impressive enough to tell people about,” said Robert Temple of the Food and Drug Administration.
The agency will consider broadening the current warning against taking ACE inhibitors late in pregnancy, he said. The immediate message is that women trying to become pregnant should switch to a different blood pressure drug, Temple said. The FDA will send letters to American clinicians with that advice.
About one-third of the defects involved the heart, one-quarter the limbs or face, and one-tenth the brain or spinal cord, the study found. Many are curable with surgery or other treatment. Others, however, cause permanent disability or retardation.
Cooper and his colleagues looked at 29,507 births to women covered by Medicaid in Tennessee between 1985 and 2000.
Of that group, 209 babies were born to women who took an ACE inhibitor during the first trimester, and 18 had birth defects. Among 202 babies born to mothers taking some other blood-pressure medicine, only four had defects.
ACE inhibitors, the acronym stands for “angiotensin-converting enzyme” have become more popular over time. A government survey of visits to doctors’ offices found their use doubled from 1995 to 2002.