Is azithromycin (a macrolide antibiotic) safe during pregnancy?

From the Guidelines

Azithromycin is generally considered safe during pregnancy when medically necessary, as indicated by its classification as FDA pregnancy category B and supported by studies such as 1.

Key Points to Consider

• Azithromycin is often preferred over other antibiotics for treating certain infections during pregnancy, including respiratory tract infections, chlamydia, and other bacterial infections.
• The typical adult dose is 500 mg on day one, followed by 250 mg daily for 4 more days for most infections, though single-dose regimens (1 gram) may be used for certain conditions like chlamydia.
• Azithromycin works by inhibiting bacterial protein synthesis, and it concentrates in tissues, allowing for once-daily dosing and shorter treatment courses.
• While considered relatively safe, it should still only be used during pregnancy when the potential benefit justifies the potential risk to the fetus, and treatment decisions should be made in consultation with a healthcare provider who can evaluate individual circumstances and the specific infection being treated.
• An epidemiological study suggests a very low risk of hypertrophic pyloric stenosis in infants exposed to macrolides, including azithromycin, during the first 13 days of breastfeeding, but not after 2 weeks, as noted in 1.

Important Considerations for Use

• The use of azithromycin during pregnancy should be based on the potential benefits outweighing the potential risks, as with any medication.
• Healthcare providers should consult the latest guidelines and studies, such as those published in the European Respiratory Journal 1, to inform their decision-making.
• Patients should be informed about the potential risks and benefits of azithromycin use during pregnancy and breastfeeding, to ensure they can make informed decisions about their care.

From the FDA Drug Label

PregnancyTeratogenic Effects. Pregnancy Category B Reproduction studies have been performed in rats and mice at doses up to moderately maternally toxic dose concentrations (i.e., 200 mg/kg/day). These doses, based on a mg/m2 basis, are estimated to be 4 and 2 times, respectively, the human daily dose of 500 mg. In the animal studies, no evidence of harm to the fetus due to azithromycin was found. There are, however, no adequate and well-controlled studies in pregnant women Because animal reproduction studies are not always predictive of human response, azithromycin should be used during pregnancy only if clearly needed.

Azithromycin use in pregnancy is categorized as Pregnancy Category B. While animal studies have shown no evidence of harm to the fetus, there are no adequate and well-controlled studies in pregnant women. Therefore, azithromycin should be used during pregnancy only if clearly needed 2.

From the Research

Safety of Azithromycin in Pregnancy

• The use of azithromycin in pregnancy has been studied, and the results are mixed 3.
• Some studies have reported increased risks of spontaneous miscarriage, major congenital malformations, cardiovascular malformations, digestive system malformations, preterm birth, and low birth weight, while others have found no association 3.
• Azithromycin is categorized as pregnancy class B, and the data for risk of congenital malformations associated with its use during pregnancy ranges from no risk to a small increased risk 4.
• The benefits of azithromycin treatment should be weighed against the potential risks, and it should only be used during pregnancy when clinically indicated 3.

Azithromycin Use in Pregnancy for Specific Conditions

• Azithromycin is useful for the treatment of sexually transmitted diseases, toxoplasmosis, and malaria in pregnant women 3.
• It is also used in the management of preterm pre-labor rupture of membranes and as adjunctive prophylaxis for cesarean delivery 3, 5.
• A study found that adjunctive azithromycin prophylaxis for prelabor cesarean birth was associated with lower odds of postpartum infection 5.

Comparison with Other Antibiotics

• Azithromycin is one of several antibiotics that may be used during pregnancy, and its safety profile is similar to that of other macrolides 6, 7.
• Other antibiotics, such as beta-lactams, vancomycin, nitrofurantoin, metronidazole, clindamycin, and fosfomycin, are generally considered safe and effective in pregnancy 6.
• Fluoroquinolones and tetracyclines are generally avoided in pregnancy due to potential risks to the fetus 6.