Antimicrobials in pregnancy

Principles

• Use medications only if absolutely necessary
• If possible, avoid therapy during the first trimester
• Use a safe medication
• Use the narrowest spectrum and shortest course
• When possible, use a single agent

Specific Antimicrobials

Generally considered safe in pregnancy:

• Penicillins, including amoxicillin, ampicillin
• Cephalosporins, including cefaclor, cephalexin, although they have been associated with kernicterus (ceftriaoxone)
• Azithromycin, which is preferred to erythromycin and clindamycin
• Vancomycin, daptomycin, fidaxomicin
• Nitrofurantoin, although it has been associated with orofacial clefts including cleft lip and cleft palate
• Metronidazole, though topical should be avoided
• Fosfomycin

Avoid unless benefits outweight risks:

• Fluoroquinolones, based on animal data of bone and cartilage damage
• Linezolid
• Polymixins
• Cotrimoxazole: avoid in first trimester (congenital malformations), and after 32 weeks (risk of kernicterus); has been associated with diaphragmatic hernia and esophageal atresia

Should be avoided altogether:

• Tigecycline
• Aminoglycosides: streptomycin associated with hearing loss, while others may be used for short courses
• Tetracyclines can discolor a developing baby's teeth and aren't recommended after the 15th week of pregnancy

Further Reading

• A Review of Antibiotic Use in Pregnancy. Pharmacotherapy. 2015;35(11):1052-62. doi: 10.1002/phar.1649