Is Clarithromycin (Biaxin) Safe During Pregnancy?

What does the evidence say about clarithromycin during pregnancy?

1. A prospective multicenter study followed 157 pregnancies and found no significant major- or minor-malformation difference versus nonteratogenic-antibiotic controls, while spontaneous abortions were more frequent in the clarithromycin group and required further study. 1
2. In a Danish register cohort, 401 first-trimester clarithromycin exposures were associated with miscarriage after adjustment, but major malformations among 253 live births were not increased and the analysis could not resolve confounding by infection. 2
3. A 2026 two-center retrospective cohort found 8 major anomalies among 347 clarithromycin-exposed pregnancies, with no statistically significant difference from beta-lactam or control-drug groups, but confidence intervals were wide. 3
4. The U.S. Biaxin label says the limited published human data are insufficient to establish drug-associated risks and describes animal malformations at clinically relevant body-surface-area exposures. 4
5. A meta-analysis of 12 observational studies reported a clarithromycin-miscarriage association, but the authors cautioned that limitations in the available data restrict causal interpretation. 5

Is clarithromycin safe in each trimester?

• First trimester. Human malformation studies are mostly reassuring but imprecise, while several observational studies reported a miscarriage association that may reflect infection or other confounding. Ask whether a better-studied antibiotic fits the infection.
• Second trimester. Later-pregnancy clarithromycin data are much thinner than first-trimester malformation data. Culture results, infection site, allergies, and local resistance should drive the antibiotic choice.
• Third trimester. Do not substitute, delay, or stop an antibiotic without the prescriber. Clarithromycin-specific evidence remains limited for preterm delivery, low birth weight, neonatal complications, and later neurodevelopment.