New research finds antibiotics linked to increased risk of miscarriage

Many types of commonly-prescribed antibiotics have been linked with an increased risk of miscarriage in early pregnancy, according to new research.

A new study published in the CMAJ (Canadian Medical Association Journal) has found that popular classes of antibiotics, such as macrolides, quinolones, tetracyclines, sulfonamides and metronidazole, increase the risk of miscarriage - in some cases by as much as 60 percent. However, both Erythromycin and Macrobid, which are often used to treat urinary tract infections in pregnant women, were not found to be associated with increased risk. Dr Anick Bérard, of the Université de Montréal in Canada, and her team looked at data from the Quebec Pregnancy Cohort between 1998 and 2009. For this study, 8,702 cases, defined as clinically detected miscarriages, were matched with 87,020 controls. The average gestational age at the time of miscarriage was 14 weeks of pregnancy. A total of 1,428 (16.4 percent) cases were exposed to antibiotics during early pregnancy compared to 11,018 (12.6 percent) in control groups. Dr Bérard commented on the findings:

"Infections are prevalent during pregnancy. Although antibiotic use to treat infections has been linked to a decreased risk of prematurity and low birth weight in other studies, our investigation shows that certain types of antibiotics are increasing the risk of spontaneous miscarriage, with a 60 percent to two-fold increased risk."

Participants in the study were between the ages of 15 and 45 years and covered under the Canadian city's drug insurance plan. Women who miscarried were more likely to be older, living alone and to have multiple health issues and infections, all of which were taken into account in the research. Bérard says the findings are significant:

"Given that the baseline risk of miscarriage can go as high as 30 percent, this is significant. But the increased risk was not seen for all antibiotics, which is reassuring for users and prescribers."

The researchers hope that the findings will prove helpful for policy-makers to update guidelines for the treatment of infections during pregnancy. Join the conversation on Twitter @HerFamilydotie