Is Amoxicillin Safe in Pregnancy?
Yes, amoxicillin is safe to use during pregnancy and is considered a first-line antibiotic for treating bacterial infections in pregnant women. 1, 2
Evidence Supporting Safety
Amoxicillin is classified as "Compatible" for use during pregnancy according to multiple clinical practice guidelines. 1 The FDA drug label states that reproduction studies in mice and rats at doses up to 3-6 times the human dose showed no evidence of harm to the fetus, though it notes that animal studies are not always predictive of human response. 2
Key Safety Data:
No teratogenic effects have been documented with amoxicillin use, unlike tetracyclines and fluoroquinolones which are contraindicated in pregnancy 1, 3
A population-based study of 401 pregnant women in Denmark found no increased risk of adverse pregnancy outcomes including low birth weight, preterm delivery, congenital malformations, spontaneous abortion, or perinatal death with amoxicillin exposure 4
Decades of clinical experience with penicillins have documented their overall safety for the fetus 3
Clinical Applications During Pregnancy
Amoxicillin is specifically recommended for multiple infections in pregnant women:
Chlamydia trachomatis infections: 500 mg orally every 8 hours as an alternative when erythromycin cannot be tolerated, with a 98.4% cure rate 1, 5
Anthrax post-exposure prophylaxis: 500 mg every 8 hours for 60 days when susceptibility testing confirms penicillin susceptibility 6, 1
Salmonella gastroenteritis: Recommended to prevent extraintestinal spread that could lead to placental and amniotic fluid infection 1
Uncomplicated urinary tract infections: 500 mg IV/PO every 8 hours for 3-7 days 6
Important Caveats and Precautions
Amoxicillin-Clavulanic Acid Combination:
- Use with caution in women at risk of preterm delivery due to theoretical (though not evidence-based) risk of necrotizing enterocolitis in the fetus 1
Drug Interactions:
May reduce efficacy of combined oral contraceptives by affecting intestinal flora and estrogen reabsorption 2
Can cause transient decrease in plasma concentration of conjugated estriol and estradiol 2
May increase INR in patients on oral anticoagulants, requiring monitoring 2
Dosing Considerations:
Amoxicillin should only be used when clearly needed, as with any medication in pregnancy 2
The drug is excreted in breast milk and may lead to sensitization of infants, though it is considered compatible with breastfeeding 1, 2
Comparison to Other Antibiotics
Amoxicillin is preferred over several other antibiotic classes during pregnancy:
Fluoroquinolones should be avoided entirely during pregnancy 1
Tetracyclines are contraindicated after the fifth week of pregnancy due to known fetal toxicity 3, 7
Aminoglycosides have known toxic effects on the fetus and should be avoided unless maternal necessity justifies fetal exposure 3, 7
Bottom Line for Clinical Practice
Penicillins, including amoxicillin, represent first-line antibiotic treatment during pregnancy except in cases of maternal penicillin allergy. 7 The extensive clinical experience and favorable safety profile make amoxicillin an appropriate choice when bacterial infection requires treatment in pregnant women. 3, 8