Cholesterol Drugs Tied to Birth Defects

U.S. study finds high number of abnormalities in babies of women taking statins

WEDNESDAY, April 7, 2004 (HealthDayNews) -- If you're pregnant or thinking about getting pregnant, there's one more group of medications to add to the long list of drugs you shouldn't take because they can harm your baby: the cholesterol-lowering medications called statins.

Researchers from the U.S. National Institutes of Health found that statin use during the first trimester of pregnancy is associated with severe central nervous system defects and limb deformities.

Their findings, published in a research letter in the April 8 issue of the New England Journal of Medicine, showed that 20 of 52 babies exposed to statins in the womb were born with malformations.

"We can't tell whether the defects were caused by the use of statin medications, but other birth defect studies suggest that these are the kinds of problems that occur if the embryo does not get enough cholesterol in early pregnancy to develop normally," said one of the study's authors, Dr. Maximilian Muenke, a senior investigator and chief of the medical genetics branch at the National Human Genome Research Institute in Bethesda, Md.

Statins are commonly used medications that help lower blood cholesterol levels. Muenke said most people who use these medications are older than 45, but that 1 to 3 percent of the prescriptions for these medications are for women in their childbearing years.

These medications are already considered contraindicated in pregnancy, and the Food and Drug Administration requires that all statin prescriptions carry a warning about taking them during pregnancy, Muenke added.

"FDA took this action because it was recognized that fetal cholesterol synthesis was essential for development, and because animals given statins during pregnancy had offspring with a variety of birth defects," he said.

The real problem, according to Dr. Nancy Green, medical director for the March of Dimes, is that about half of all pregnancies are unplanned, so exposure to drugs can happen inadvertently before a woman even knows she's pregnant.

"Statins are very good for general health. But there's a lot we don't know about their safety in pregnancy because there is no national system for monitoring the safety of drugs during pregnancy," Green noted.

"This report is worrisome," she added.

Muenke and NIH colleague Dr. Robin Edison reviewed the 52 reports to the FDA of statin exposure in the first trimester of pregnancy that occurred from 1987 through 2001.

Of the 20 babies born with malformations, five had severe central nervous system defects, and five had malformed limbs. One baby had both, according to Muenke. There were also two cases of a very rare birth defect called holoprosencephaly, which occurs when the brain fails to divide properly.

"These are such very rare birth defects that one would not expect to find the number we found in a population this small," Muenke said.

He added that it's hard to know if there are more birth defects found in women who take statins, because the FDA reporting system is voluntary and many women don't report early-pregnancy statin exposure.

Green said the study highlights the need for a more comprehensive reporting system for medication use during pregnancy. With such a system, health-care providers could know if a medication was safe for use during pregnancy or not.

"For most drugs, we can't say for sure if they're safe. That often leads to under-treatment," Green said.

"Our study supports the need for [warning labels on statins], and it points to the need for larger, controlled studies to better define the risks of using statins in pregnant women," Muenke added.

"In the meantime, if a woman becomes unexpectedly pregnant while taking statins, she should immediately consult with her physician," he said.

More information

To learn more about medications and pregnancy, visit the March of Dimes or the U.S. Food and Drug Administration.

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