The women involved in the study were from the Quebec Pregnancy Cohort, who were studied for the fetal effects of various antibiotics beginning from the first day of gestation. The data was adjusted for other factors which may cause miscarriages, such as women taking teratogenic/ fetotoxic medications or who had planned abortions. The women were ages 15-45 years old.

Different antibiotics may cause miscarriages via different mechanisms. For example, clarithromycin may alter cardiac rhythm in the developing fetus, while quinolone may interfere with the DNA replication process and inhibit mitosis. It is also known that tetracycline inhibits important enzymes required for tissue remodeling, while metronidazole may cause DNA damage by increasing the production of reactive intermediates.

The results of this study pose a new challenge to prescribers, who must weigh the benefits versus risks of not taking antibiotics to treat bacterial infections, which can create a dangerous environment for a developing fetus. However, several antibiotics are still considered safe during pregnancy, including penicillin, erythromycin, nitrofurantoin, and cephalosporin. Luckily, these antibiotics are commonly prescribed for women to treat common issues such as urinary tract infections.

These findings are significant because they have the potential to cause guideline changes for the treatment of infections in pregnant women. This information also gives increased awareness to pharmacists who may now give a second thought to dispensing these antibiotics to pregnant women and consult with their prescriber first, and will likely change their medication counselling of these antibiotics when dispensing them to pregnant women.

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References:

Muanda, F. T., Sheehy, O., & Berard, A. (2017, May 1). Use of antibiotics during pregnancy and risk of spontaneous abortion. Canadian Medical Association Journal, 189(17), 5-9.
Mulholland, A. (2017, May 1). Certain antibiotics linked to increased risk of miscarriage, study confirms. In ctvnews.ca. Retrieved July 30, 2017.