New Risk in Blood Pressure Drugs

A popular class of drugs used to treat high blood pressure appears to cause birth defects when taken in the first trimester of pregnancy and should be avoided by women of childbearing age, according to a new study.

Women who took ACE inhibitors in the early stages of pregnancy were 2.7 times more likely to have babies with birth defects than women who were not on anti-hypertensive medication, researchers reported today in the New England Journal of Medicine.

Most of those birth defects involved malformations in the cardiovascular and central nervous systems.

ACE inhibitors were known to be dangerous in the later stages of pregnancy because of their potential to interfere with fetal kidney function. As a result, physicians generally switch their patients to other blood pressure medications as soon as a pregnancy is confirmed.

The Food and Drug Administration already advises women to stop taking the drugs when they become pregnant. That official warning will not be strengthened until additional data are reviewed, said Dr. Sandra Kweder, deputy director of the FDA’s Office of New Drugs.

The researchers at Nashville’s Vanderbilt University and Boston University combed through 15 years’ worth of Tennessee Medicaid data in search of evidence that exposure to ACE inhibitors in the first trimester is dangerous.

They identified 209 infants whose mothers took the drugs only during the first three months of pregnancy and found that 7.1% had some kind of birth defect.

Among the 29,096 babies whose mothers didn’t take blood pressure medication, the rate of birth defects was 2.6%.

ACE inhibitors are increasingly popular with women of childbearing age, according to the National Ambulatory Medical Care Survey. The study noted that 4.4% of women ages 15 to 44 were taking the drugs in 2002, up from 2.4% in 1995.

The researchers also found 202 babies whose mothers took other kinds of anti-hypertension drugs during the first trimester. Their rate of birth defects was 1.7%.