Numerous classes of antibiotics were associated with an uptick in risk of miscarriages, according to a study published in Canadian Medical Association Journal. These classes of common antibiotics include macrolides, quinolones, tetracyclines, sulfonamides and metronidazole.
Researchers examined 8,702 cases, defined as clinically detected spontaneous abortions. They matched the cases with 87,020 control cases. The miscarriage occurred at 14 weeks of pregnancy.
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The study shows that 1,428 (16.4 percent), of the miscarriage cases were exposed to antibiotics during early pregnancy, as compared to 11,018 (12.6 percent) among the control cases. However, erythromycin and nitrofurantoin (a common treatment for urinary tract infections in pregnant women) were not associated with increased risk.
"Infections are prevalent during pregnancy," said Dr. Anick Bérard, of the Université de Montréal in Canada and a study author. "Although antibiotic use to treat infections has been linked to a decreased risk of prematurely and low birth weight in other studies, our investigation shows that certain types of antibiotics are increasing the risk of spontaneous abortion, with a 60 percent to two-fold increased risk."