Several classes of commonly used antibiotics, such as quinolones and tetracyclines, may be associated with an increased risk of miscarriage in early pregnancy, according to new Canadian research published May 1.
The risk of miscarriage linked to taking antibiotics during pregnancy could be raised by as much as between 60 and 100 percent, according to research from the Université de Montréal in Canada, studying data from 95,722 women aged between 15 and 45 years old.
The study identified five classes of antibiotics associated with increased miscarriage risk, including macrolides, used to treat infections of the ears, nose and throat, airways, lungs, skin, genitals and mouth.
The others are quinolones (genital, urinary, intestinal, nose and throat infections, and cystitis), tetracyclines (infectious diseases, notably of the respiratory tract and genitals, plus acne), sulfonamides and metronidazole (abdominal, vaginal and intestinal infections).
However, erythromycin was not associated with a higher risk of miscarriage, according to the study, published in The Canadian Medical Association Journal, nor was nitrofurantoin, which is often used to treat urinary tract infections in pregnant women.
The authors studied a group of 8,702 cases, defined as clinically detected spontaneous abortions. Mean gestational age at the time of miscarriage was 14 weeks of pregnancy. This group was matched with a control group of 87,020 women. A total of 1,428 cases, or 16.4 percent, were exposed to antibiotics during early pregnancy compared to 11,018, or 12.6 percent, of the control group.
The authors point out that 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 analyses. The study also notes that the severity of the infection treated by antibiotics should be taken into account as a potential cofactor for miscarriage risk. JB