Use of Certain Antibiotics in Pregnancy Tied to Spontaneous Abortion — Physician’s First Watch
Use of Certain Antibiotics in Pregnancy Tied to Spontaneous Abortion
By Amy Orciari Herman
Many commonly used antibiotics seem associated with increased risk for spontaneous abortion, according to a case-control study in the Canadian Medical Association Journal.
Using data from a Quebec prescription database, researchers matched 8700 cases of spontaneous abortion to 87,000 control pregnancies that did not end in spontaneous abortion. Antibiotics had been used during early pregnancy in roughly 16% of cases and 13% of controls.
After multivariable adjustment, compared with no antibiotic use, the following antibiotics and antibiotic classes were associated with significantly increased risk for spontaneous abortion: azithromycin, clarithromycin, tetracyclines, doxycycline, minocycline, quinolones, ciprofloxacin, norfloxacin, levofloxacin, sulfonamides, and metronidazole. (The majority of these drugs were associated with a roughly twofold increase in risk, but the number of exposed cases reached as low as 8 in one instance). Neither erythromycin nor nitrofurantoin was associated with increased risk. Findings were similar when penicillins or cephalosporins were used as the reference group.
Dr. Anna Wald of NEJM Journal Watch Women's Health commented: "The results of this study suggest that penicillins and cephalosporins should be drugs of choice in the first half of pregnancy, when appropriate. The difficulty in interpreting this study is that the indications for which women received non-penicillin antibiotics may in themselves increase the risk of spontaneous abortion." Ultimately, she said, "the role of antibiotics in these outcomes is not that clear."