From the Guidelines
Azithromycin is considered probably safe during pregnancy, with no evidence of risk in humans, and can be used when the benefits outweigh the risks, as indicated in the most recent study from 2020 1.
Key Points to Consider
- Azithromycin is classified as FDA pregnancy category B, indicating no evidence of risk in humans.
- The standard adult dosing is typically 500mg on day 1, followed by 250mg daily for 4 more days for most infections, though a single 1g dose may be used for certain conditions like chlamydia.
- Azithromycin is often preferred over other antibiotics during pregnancy because it has good tissue penetration, a long half-life allowing for once-daily dosing, and fewer concerning drug interactions.
- It is particularly useful for respiratory infections, sexually transmitted infections like chlamydia, and certain community-acquired pneumonias.
- The medication works by inhibiting bacterial protein synthesis by binding to the 50S ribosomal subunit.
- While generally well-tolerated, potential side effects include gastrointestinal disturbances, which can be minimized by taking with food.
- An epidemiological study suggests a very low risk of hypertrophic pyloric stenosis in infants exposed to macrolides during the first 13 days of breastfeeding, but not after 2 weeks 1.
- Azithromycin does not appear to increase the risk of birth defects or adverse pregnancy outcomes based on available data, making it a reasonable antibiotic choice when indicated during pregnancy, as also supported by earlier guidelines from 2006 1.
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 should be done with caution. The drug is classified as Pregnancy Category B, and 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 only be used during pregnancy if clearly needed 2.
From the Research
Azithromycin Use in Pregnancy
- Azithromycin is a commonly prescribed antibiotic during pregnancy, with good oral bioavailability and transplacental transfer, making it suitable for treating various infections 3.
- The drug is used to manage preterm pre-labor rupture of membranes, adjunctive prophylaxis for cesarean delivery, and to treat sexually transmitted diseases, toxoplasmosis, and malaria 3.
Safety and Efficacy
- Studies have yielded conflicting results regarding the safety of azithromycin use during pregnancy, with some reporting increased risks of spontaneous miscarriage, major congenital malformations, and preterm birth, while others found no significant associations 3, 4.
- A systematic review and meta-analysis found that prophylactic azithromycin during pregnancy reduced the risk of low birth weight and prematurity, but had no strong effect on neonatal mortality, infections, and admissions 4.
Clinical Applications
- Azithromycin is recommended as a single-dose therapy for the treatment of chlamydial infection, and is an alternative agent for the treatment of other sexually transmitted diseases 5.
- The antibiotic is also used to treat acne during pregnancy, as part of a comprehensive management plan that includes topical and systemic treatments 6.
- Azithromycin is utilized in the treatment of common bacterial and viral infections in pregnant patients, including pelvic inflammatory disease, gonococcal infections, and community-acquired pneumonia 7.
Considerations for Use
- Azithromycin should only be used during pregnancy when clinically indicated, and the benefits of treatment are expected to outweigh the potential risks 3.
- Clinicians should weigh the antimicrobial dosing, pharmacokinetics, safety, and established effectiveness of azithromycin when making empirical management decisions during pregnancy 7.