What antibiotics are safe during pregnancy?

Safe Antibiotics During Pregnancy

Penicillins and cephalosporins are the safest antibiotics to use during pregnancy, with amoxicillin, amoxicillin-clavulanate, and cephalexin being first-line options. 1

First-Line Safe Antibiotics

Penicillins

• Amoxicillin is considered safe throughout pregnancy (FDA Category B) with no evidence of harm to the fetus based on extensive clinical experience 1, 2
• Amoxicillin-clavulanate (Augmentin) is compatible with pregnancy, though it's not recommended in women at risk of preterm delivery due to very low risk of necrotizing enterocolitis in the fetus 1
• All penicillins are generally considered low risk in pregnancy 1

Cephalosporins

• Cephalexin is recommended as first-line therapy during pregnancy with moderate evidence supporting its safety 1
• Cefuroxime and other cephalosporins are compatible with pregnancy, with human data indicating they are not teratogenic at usual therapeutic doses 1
• Most studies confirm that cephalosporin antibiotics in general are safe to use during pregnancy 1

Macrolides

• Azithromycin is considered safe during pregnancy (FDA Category B) with moderate evidence supporting its use 1
• Erythromycin (Category B) is probably safe, particularly in second and third trimesters 1
• Avoid erythromycin estolate due to potential maternal hepatotoxicity 1

Second-Line Options

Clindamycin

• Moderate evidence supports clindamycin's safety in pregnancy 1
• May be considered when first-line agents are not appropriate 1
• Can be used as monotherapy, though data are less robust than for combination therapy 1

Metronidazole

• Can be used during pregnancy if there are no safer alternatives 1
• Associated with possible increased risk of low birthweight and neuroblastoma (low quality evidence) 1
• Earlier concerns about teratogenesis in humans have not been confirmed by recent data 3

Nitrofurantoin

• Generally considered safe and effective in pregnancy, particularly for urinary tract infections 4
• Should be avoided near term due to theoretical risk of hemolytic anemia in neonates with G6PD deficiency 4

Antibiotics to Avoid During Pregnancy

Tetracyclines

• Strong recommendation to avoid doxycycline due to risk of congenital anomalies, binding to fetal bones, and tooth discoloration 1
• Tetracyclines should be avoided after the fifth week of pregnancy 5
• Categorized as FDA Category D, contraindicated during second and third trimesters 1

Fluoroquinolones

• Ciprofloxacin and other fluoroquinolones should generally be avoided during pregnancy 1, 6
• In animal studies, fluoroquinolones may be associated with fetal cartilage damage, though human data suggest low risk 1
• If a fluoroquinolone is absolutely necessary, ciprofloxacin is preferred 1

Aminoglycosides

• Should be avoided if possible due to risk of eighth cranial nerve toxicity in the fetus 1, 5
• Only used as second or third-line treatment in mothers with severe infection when other antibiotics have failed 1
• If necessary, monitor levels carefully and use once-daily dosing 1

Other Antibiotics to Avoid

• Co-trimoxazole (trimethoprim/sulfamethoxazole): Avoid due to increased risk of preterm birth, low birthweight, and kernicterus 1
• Trimethoprim: Avoid, especially during first trimester 1
• Dapsone: Avoid due to risk of preterm birth, low birthweight, and hemolysis 1

Special Considerations

• Antibiotic selection should be guided by the specific infection being treated and local resistance patterns 4
• Physiological changes in pregnancy (increased glomerular filtration rate, increased total body volume) may require dosage adjustments 4
• For severe infections, the benefit of appropriate antibiotic therapy outweighs potential risks to the fetus 5
• When treating pregnant women with antibiotics, consider monitoring for adverse effects more closely than in non-pregnant patients 7

Conclusion for Clinical Practice

When prescribing antibiotics during pregnancy, follow this algorithm:

1. First consider penicillins (amoxicillin, amoxicillin-clavulanate) or cephalosporins (cephalexin, cefuroxime) 1
2. If penicillin allergy exists, consider azithromycin or clindamycin based on the infection type 1
3. For anaerobic infections requiring treatment, metronidazole may be used if benefits outweigh risks 1, 3
4. Always avoid tetracyclines, fluoroquinolones, and aminoglycosides unless absolutely necessary for maternal health 1, 5