Is ertapenem (a carbapenem antibiotic) safe to use during the last month of pregnancy?

Ertapenem Use During the Last Month of Pregnancy

Ertapenem can be used during the last month of pregnancy if the potential benefit justifies the potential risk to the fetus, as it is classified as a category B drug by the FDA. 1

Safety Profile of Ertapenem in Pregnancy

• The FDA pregnancy risk classification for ertapenem is Category B, indicating that animal reproduction studies have not demonstrated fetal risk, but there are no adequate and well-controlled studies in pregnant women 1
• According to the FDA drug label, available data from a small number of post-marketing cases with ertapenem use in pregnancy are insufficient to inform any drug-associated risks for major birth defects, miscarriage, or adverse maternal or fetal outcomes 1
• Animal studies show no evidence of developmental malformations in rats at systemic exposures up to approximately 1.2 times the human exposure at the maximum recommended human dose 1

Carbapenems in Pregnancy

• In the 2020 ERS/TSANZ task force statement, meropenem (another carbapenem) is listed as "possibly safe" during the first trimester and "probably safe" during the second and third trimesters 2
• Carbapenems are generally considered when other safer alternatives fail to control infection, particularly for severe infections 2
• A 2025 Mayo Clinic Proceedings review suggests ertapenem as an alternative to conventional peripartum antibiotic regimens, indicating its potential use in pregnancy when clinically indicated 2

Clinical Decision-Making Algorithm

1. Assess infection severity and necessity:

   • Determine if the infection requires carbapenem therapy (e.g., resistant organisms, failure of first-line agents) 2
   • Consider if other pregnancy-compatible antibiotics would be effective 2

2. Consider alternative antibiotics first:

   • Beta-lactams (penicillins, cephalosporins) are generally considered first-line during pregnancy 3
   • Cephalosporins are listed as "compatible" during pregnancy in guidelines 2

3. When to use ertapenem:

   • When first-line antibiotics are ineffective or contraindicated 2
   • For severe infections requiring broad-spectrum coverage 4
   • When the benefit of treating the maternal infection outweighs potential risks 1

Important Considerations

• Physiological changes in pregnancy may affect pharmacokinetics, potentially requiring dose adjustments or careful monitoring 5
• Ertapenem has been studied for specific obstetric infections like chorioamnionitis after cesarean delivery, showing effectiveness and potential cost benefits compared to traditional regimens 6
• Ertapenem is present in human milk, but there are no data on the effects on the breastfed infant or milk production 1

Potential Advantages of Ertapenem

• Once-daily dosing due to extended half-life (approximately 4 hours) 4, 7
• Broad-spectrum activity against many gram-positive and gram-negative aerobes and anaerobes 4
• Resistance to nearly all beta-lactamases, including extended-spectrum beta-lactamases and AmpCs 7

Potential Concerns

• Limited data specifically on use in the last month of pregnancy 1
• As with all medications during pregnancy, the benefit-risk ratio must be carefully evaluated 2
• Monitoring for any adverse effects in both mother and fetus is recommended 1

Remember that while ertapenem appears to have an acceptable safety profile based on available evidence, the decision to use it during the last month of pregnancy should be made after considering the severity of the infection, potential alternatives, and the risk-benefit ratio for both mother and fetus 1, 2.