The FDA will not change its warnings for pregnant women taking certain anti-hypertension medicines -- even though a study it cosponsored shows an elevated risk of birth defects in the first trimester.

The agency said during a conference call that it would not change its warnings for angiotensin-converting-enzyme (ACE) inhibitors because the FDA believes the study is not conclusive and existing black box warnings are sufficient to protect women's health. The study, Major Congenital Malformations after First-Trimester Exposure to ACE Inhibitors, published in The New England Journal of Medicine (NEJM), found a fetus faced 2.7 times the risk of birth defects when these inhibitors were used during the first three months of pregnancy.

NEJM recommends that the FDA warn women not to take these drugs during the first trimester. ACE inhibitors, which are used to lower blood pressure and to preserve kidney function in people with diabetes, are commonly prescribed drugs, with 42 million prescriptions written each year.

The agency said that its current black box warning that women should stop using these drugs as soon as possible when they become pregnant is sufficient to cover risks in the first trimester. The warning states that the drugs can cause injury and even death to the developing fetus when used during the second and third trimesters of pregnancy.

The FDA needs to further review the study and wants additional data before changing its warning, Sandra Kweder, deputy director of the Office of New Drugs, said. The study's findings are "considered preliminary data," she added.

However, the agency will notify the public about the study. The results are "important enough and impressive enough to tell people about," Robert Temple, associate director for medical policy, said. The FDA and HHS' Agency for Healthcare Research and Quality jointly funded the study.

The study represents the first extensive study of ACE inhibitors' use during the first trimester and illustrates a severe lack of information on such risks, NEJM said in an attached editorial. "This is not the last word on the subject, but it is shocking to realize that it is almost the first," the editorial said. (http://www.fdanews.com/did/5_112/)