Clarithromycin Use in the First Trimester Is Not Associated With Fetal Abnormalities

Area of Science:

• Pharmacology and Toxicology
• Obstetrics and Gynecology
• Teratology

Background:

• Clarithromycin, a macrolide antibiotic, is frequently prescribed, including during pregnancy.
• Limited research exists on the safety of clarithromycin monotherapy in early pregnancy.
• Evaluating pregnancy outcomes after first-trimester exposure is crucial.

Purpose of the Study:

• To assess pregnancy outcomes following first-trimester exposure to clarithromycin.
• To compare the incidence of major anomalies in women exposed to clarithromycin versus beta-lactams or known safe control drugs.
• To determine the safety profile of clarithromycin in early pregnancy.

Main Methods:

• Retrospective cohort study conducted at two centers.
• Data collected on medication use, obstetric history, and pregnancy outcomes via postal questionnaires.
• Comparison of major anomaly rates between clarithromycin, beta-lactam, and control drug groups.

Main Results:

• Incidence of major anomalies: 2.31% (clarithromycin), 1.90% (beta-lactams), 1.37% (controls).
• No statistically significant differences in major anomaly rates were observed between the groups, even after adjusting for live births or using inverse probability weighting.
• Odds ratios for major anomalies in the clarithromycin group were not significantly elevated compared to control or beta-lactam groups.

Conclusions:

• First-trimester clarithromycin exposure is not associated with an increased risk of major congenital anomalies.
• The safety profile of clarithromycin in early pregnancy appears comparable to beta-lactams and other safe control medications.
• Further research may be warranted, but current findings support its use when indicated in pregnancy.