Antibiotics may raise 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 of 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. 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.”

According to the Centers for Disease Control and Prevention, in the US birth defects occur in about 3% of babies — 120,000 a year. After adjusting for variables that might increase the risk for birth defects, they found that for some drugs, the increased risk was quite large — for example, doxycycline more than doubled the risk for cardiac abnormalities.

The study found no increase in birth defects with the use of amoxicillin, nitrofurantoin or the cephalosporins.