Certain Antibiotics May Increase Risk of Birth Defects

A large study published in the British Journal of Clinical Pharmacology found that certain antibiotics taken during pregnancy may increase the risk for birth defects.

Canadian researchers followed 139,938 mothers of babies born in Quebec from 1998 to 2008, tracking their antibiotic use in the first trimester, and their babies’ birth defects through the first year of life. The senior author, Anick Bérard, a professor of epidemiology at the University of Montreal, said that antibiotics in the class called quinolones — ciprofloxacin, levofloxacin and others — are particularly dangerous and should be avoided in pregnancy.

But she said: “Infection itself is associated with adverse pregnancy outcomes, and they must be treated. Our study shows that we must think about which antibiotics to use.”

Birth defects are common. According to the Centers for Disease Control and Prevention, in the United States about 3 percent of babies — 120,000 a year — are born with one or more. After adjusting for variables that might increase the risk for birth defects, including infections for which antibiotics are prescribed, high blood pressure, diabetes, asthma and many others, they found that for some drugs, the increased risk was quite large — for example, doxycycline more than doubled the risk for cardiac abnormalities and clindomycin increased the risk for musculoskeletal problems by 67 percent.

There were also increased risks for birth defects with the use of moxifloxacin, ofloxacin, erythromycin and penicillin V. The study found no increase in birth defects with the use of amoxicillin, nitrofurantoin or the cephalosporins.

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