What do medical sources say about Amoxicillin during pregnancy?

1st Trimester: MotherToBaby's April 2026 sheet covers amoxicillin with clavulanic acid and says most first-trimester studies did not find more birth defects. It also says a few studies of amoxicillin alone reported more cleft lip or palate, while other studies did not. A 2025 study of records from about 180 US institutions found an association between amoxicillin and clefting, but its authors said the study could not show cause. A registry study published in a 2026 journal issue found no increased miscarriage risk with amoxicillin. The NHS says amoxicillin can be taken during pregnancy, while the FDA label says to use it only if clearly needed because controlled studies in pregnant women are lacking. Ask your provider about your situation. 2nd Trimester: MotherToBaby says amoxicillin with clavulanic acid is not expected to increase preterm birth or low birth weight, though research on the combination is limited. In a Danish registry study, researchers found no higher risk of preterm birth, low birth weight, malformations, or miscarriage among 401 pregnancies with amoxicillin prescriptions, but the study was small. The NHS says amoxicillin can be taken during pregnancy, while the FDA label says to use it only if clearly needed because controlled pregnancy studies are lacking. The available studies do not give a separate second-trimester risk estimate. Ask your provider about your situation. 3rd Trimester: MotherToBaby says the combination of amoxicillin and clavulanic acid is not expected to increase preterm birth or low birth weight overall. After early breaking of the waters (PPROM), one large trial found more cases of newborn necrotizing enterocolitis (NEC), a serious bowel disease, with co-amoxiclav. This finding concerns the combination in PPROM and does not establish the same risk for amoxicillin alone in routine late pregnancy. The NHS says amoxicillin can be taken during pregnancy, while the FDA label says to use it only if clearly needed because controlled pregnancy studies are lacking. Ask your provider about your situation.

What do medical sources say about Amoxicillin while breastfeeding?

LactMed says amoxicillin reaches milk at low levels and is acceptable for nursing mothers; occasional reports of infant rash, diarrhea, or thrush have not been fully evaluated. In a 2026 milk study of 25 mother-infant pairs, the estimated relative infant dose stayed below 0.4%, and no infant effects were reported. NHS SPS lists amoxicillin among preferred penicillins during breastfeeding and recommends precautionary monitoring for full-term, healthy infants. FDA labeling says penicillins pass into milk and advises caution because infant sensitization may occur. Ask your provider about your situation.

Where do sources disagree on Amoxicillin in pregnancy or breastfeeding?

First-trimester cleft findings and pregnancy label wording The NHS says amoxicillin can be taken during pregnancy. MotherToBaby says most studies have not found more birth defects, while noting mixed cleft findings for amoxicillin alone. The FDA label says to use amoxicillin during pregnancy only if clearly needed because adequate, well-controlled studies in pregnant women are lacking. Lin et al. and Laspro et al. reported associations with cleft outcomes. The label wording reflects a lack of controlled human studies. The cleft studies use different designs and exposure records, and they report associations rather than proof of cause. Studies of overall major malformations and specific cleft outcomes do not answer exactly the same question. The evidence does not establish that amoxicillin causes clefts. Large observational cohorts have not found an increase in overall major malformations, while two studies report cleft-specific associations. The NHS and FDA label frame pregnancy use differently, so the mixed cleft finding and the reason for the label precaution are both stated.

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Amoxicillin

Medication

Penicillin-like antibiotic

Pregnancy

First-trimester major malformations: Daniel et al. (2019) linked four databases for 101,615 pregnancies. The abstract lists 6,919 total exposed and 1,045 amoxicillin-only and 6,041 amoxicillin/clavulanate exposures; those printed counts do not add up, so the total is not used to infer subgroup counts. The authors found no significant association between either exposure and major malformations overall or by organ system. Muanda et al. (2017) studied 139,938 liveborn singleton infants and found no association between first-trimester amoxicillin and major congenital malformations. Cleft signals: Lin et al. (2012), a case-control study with 877 cleft lip with or without palate cases, 471 cleft-palate-only cases, and 6,952 controls, found an adjusted OR of 2.0 (95% CI 1.0-4.1) for first-trimester amoxicillin and cleft lip with or without palate; the OR for cleft palate alone was 1.0 (95% CI 0.4-2.3). Laspro et al. (online 2024, journal issue 2025) analyzed records from about 180 US institutions and found an association between amoxicillin and orofacial clefting (OR 1.22, 95% CI 1.14-1.30). Exposure included prescriptions, provider administration, or maternal reports, and the authors said causality was not assessed. Miscarriage: Boissiere-O'Neill et al. (online 2025, journal issue 2026) studied 704,082 pregnancies in Norwegian registries and found amoxicillin was not associated with increased miscarriage risk; the abstract does not state the amoxicillin-specific exposed count. The Danish cohort by Jepsen et al. (2003) included 401 amoxicillin-exposed pregnancies and 10,237 controls; it found no significant increases in preterm delivery, low birth weight, malformations, or spontaneous abortion, but estimates were imprecise. Newborn effects: In the ORACLE I randomized trial of 4,826 women with PPROM, co-amoxiclav (250 mg amoxicillin plus 125 mg clavulanic acid) was one assigned regimen and was associated with more neonatal necrotizing enterocolitis. This is evidence about the combination after PPROM, not amoxicillin alone in routine pregnancy. A 2026 mouse study reported changes in lung development after prenatal amoxicillin exposure; this animal finding does not establish a human pregnancy effect.

Breastfeeding

LactMed (last revised June 15, 2026) reports low milk levels. It cites a single-dose study and reports six women received 1 g amoxicillin; the primary abstract describes 42 mothers across several antibiotics but does not state the amoxicillin subgroup count. LactMed estimates that the infant dose from this study would be 0.25-0.5% of a typical infant amoxicillin dose. Baklouti et al. (2026) studied 25 mother-infant pairs with 75 milk and 75 plasma samples; modeled relative infant dose remained below 0.4% using adult or pediatric dosing benchmarks, including a simulated maternal dose of 6 g/day, and no infant adverse effects were reported. LactMed also summarizes a small controlled study of 40 infants exposed to amoxicillin in milk, with two cases of diarrhea and one rash. Benyamini et al. (2005) followed 67 infants exposed to amoxicillin/clavulanate and 40 amoxicillin-only comparison infants; 15 of 67 combination-exposed infants and 3 of 40 amoxicillin-exposed infants had reported adverse effects. The reported effects were minor and self-limited, and no significant differences were found for specific events. The combination results must not be generalized to amoxicillin alone.

First-trimester cleft findings and pregnancy label wording

Source A says: The NHS says amoxicillin can be taken during pregnancy. MotherToBaby says most studies have not found more birth defects, while noting mixed cleft findings for amoxicillin alone. (NHS: Pregnancy, breastfeeding and fertility while taking amoxicillin, MotherToBaby: Amoxicillin and Clavulanic Acid fact sheet)
Source B says: The FDA label says to use amoxicillin during pregnancy only if clearly needed because adequate, well-controlled studies in pregnant women are lacking. Lin et al. and Laspro et al. reported associations with cleft outcomes. (DailyMed: Amoxicillin capsules, current label record, Lin et al. 2012: Maternal exposure to amoxicillin and the risk of oral clefts, Laspro et al. 2025: Association of commonly prescribed antepartum medications and incidence of orofacial clefting)
Why they differ: The label wording reflects a lack of controlled human studies. The cleft studies use different designs and exposure records, and they report associations rather than proof of cause. Studies of overall major malformations and specific cleft outcomes do not answer exactly the same question.
Other sources: Daniel et al. and Muanda et al. found no association between amoxicillin exposure and overall major congenital malformations in large observational cohorts. (Daniel et al. 2019: The safety of amoxicillin and clavulanic acid use during the first trimester of pregnancy, Muanda et al. 2017: Use of antibiotics during pregnancy and risk of major congenital malformations)
What the evidence shows overall: The evidence does not establish that amoxicillin causes clefts. Large observational cohorts have not found an increase in overall major malformations, while two studies report cleft-specific associations. The NHS and FDA label frame pregnancy use differently, so the mixed cleft finding and the reason for the label precaution are both stated.

Breastfeeding label caution and clinical guidance

Source A says: LactMed says amoxicillin reaches milk at low levels and is acceptable for nursing mothers. NHS SPS lists amoxicillin among preferred penicillins during breastfeeding for full-term, healthy infants, with precautionary monitoring. (LactMed: Amoxicillin, NHS Specialist Pharmacy Service: Using penicillin antibiotics during breastfeeding)
Source B says: The DailyMed label says penicillins pass into human milk, amoxicillin may lead to infant sensitization, and caution should be exercised. (DailyMed: Amoxicillin capsules, current label record)
Why they differ: The product label presents a precaution about possible sensitization, while LactMed and NHS SPS weigh the low measured milk levels and available infant follow-up. The human infant studies are small, so monitoring remains part of the clinical guidance.
Other sources: The NHS says only tiny amounts enter milk and describes reported infant symptoms as mild and rare. (NHS: Pregnancy, breastfeeding and fertility while taking amoxicillin)
What the evidence shows overall: The sources agree that amoxicillin enters milk and that infant symptoms can occur, but differ in how they frame the evidence. LactMed considers it acceptable, NHS SPS supports its use with monitoring for full-term, healthy infants, and the label retains a caution about sensitization.

Last reviewed 2026-10-16

Independent check 2026-10-16

Not yet clinician-reviewed

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Amoxicillin

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