Certain types of antibiotics, when used in the early months of pregnancy, are associated with an increased risk of miscarriage, according to a study in the Canadian Medical Association Journal. Drugs such as macrolides, quinolones, tetracyclines, sulfonamides, and metronidazole were related to higher rates of pregnancy loss. The most commonly prescribed antibiotics (penicillin, cephalosporin, erythromycin) were not associated with increased risk of miscarriage.
In a 2013 study, Danish researchers compared around 8,700 cases of miscarriages, occurring on average in the fourteenth week of pregnancy, with roughly 87,000 successful pregnancies. Of the women who miscarried, 16.4 percent had taken antibiotics during early pregnancy. The general risk of miscarriage is 6 to 7 percent; the study showed that taking certain antibiotics increased the risk to 9 to 10 percent.
“Infections are prevalent during pregnancy,” Dr. Anick Bérard of the Université de Montréal in Quebec told Newsmax. Dr. Berard noted that using antibiotics to treat infections appears to decrease the risk of prematurity and low birth weight in other studies, but “our investigaton shows that certain types of antibiotics are increasing the risk of spontaneous abortion [i.e., miscarriage], with a 60 percent to two-fold increased risk.”
The increased risk, researchers have found, is not found in all antibiotics, which is “reassuring for users, prescribers, and policy-makers,” Dr. Berard stated.