Is Augmentin (amoxicillin-clavulanate) safe to use intravenously (IV) at 36 weeks of pregnancy?

IV Augmentin at 36 Weeks Pregnancy

IV amoxicillin-clavulanate (Augmentin) is classified as Pregnancy Category B and can be safely used at 36 weeks of pregnancy when clinically indicated, though it is not a first-line agent for routine Group B Streptococcus prophylaxis. 1

Safety Profile During Late Pregnancy

The FDA drug label confirms that amoxicillin-clavulanate is Pregnancy Category B, meaning reproduction studies in pregnant rats and mice at doses up to 1200 mg/kg/day revealed no evidence of fetal harm. 1 However, the label notes that oral ampicillin-class antibiotics are poorly absorbed during labor, and it is unknown whether use during labor or delivery has adverse effects on the fetus or prolongs labor. 1

• Animal studies at doses 4 times (rats) and 2 times (mice) the maximum recommended adult human dose showed no teratogenic effects. 1
• No adequate and well-controlled studies exist in pregnant women, so the drug should be used only if clearly needed. 1
• Amoxicillin is excreted in human milk and may lead to infant sensitization. 1

Clinical Context at 36 Weeks Gestation

At 36 weeks, several important considerations apply:

• Women on anticoagulation for prosthetic valves should be switched from oral anticoagulants to LMWH or unfractionated heparin from the 36th week. 2
• GBS screening is recommended at 36 0/7 to 37 6/7 weeks gestation with vaginal-rectal culture. 3
• For preterm labor or PPROM scenarios at <37 weeks, ampicillin 2 g IV once followed by 1 g IV every 6 hours for at least 48 hours is adequate for both latency and GBS prophylaxis. 3

When IV Augmentin is Appropriate vs. Alternatives

For GBS Prophylaxis (NOT Recommended as First-Line)

For intrapartum GBS prophylaxis, penicillin G (5 million units IV initially, then 2.5-3.0 million units every 4 hours) is the preferred agent due to its narrow spectrum and universal GBS susceptibility. 2, 4

• Ampicillin (2 g IV initially, then 1 g every 4 hours) is an acceptable alternative but has broader spectrum activity. 2, 4
• Augmentin is NOT listed as a recommended agent for routine GBS prophylaxis in CDC guidelines. 2

For Penicillin-Allergic Patients

For patients without high-risk allergy features, cefazolin (2 g IV initially, then 1 g every 8 hours) is the preferred alternative. 5

• For high-risk allergy (anaphylaxis, angioedema, respiratory distress, urticaria), clindamycin 900 mg IV every 8 hours (if susceptible) or vancomycin 1 g IV every 12 hours should be used. 4, 5

For Chorioamnionitis or Broader Coverage

When chorioamnionitis is suspected, broader spectrum agents active against GBS and other organisms (including E. coli and gram-negative pathogens) are necessary. 4

• In this scenario, ampicillin-based regimens including amoxicillin-clavulanate may be appropriate as they provide coverage beyond GBS alone. 4

General Safety of Beta-Lactams in Pregnancy

Penicillins and cephalosporins are first-line antibiotics during pregnancy with extensive safety data. 6

• Beta-lactams have a long history of use without significant deleterious effects on fetuses. 7
• Penicillins are considered to have "none" teratogenic potential based on "good data." 8
• Amoxicillin has "unlikely" teratogenic potential based on "fair data." 8

Critical Dosing Considerations

Significant pharmacokinetic changes occur during pregnancy for penicillins, indicating that dosage adjustments may be necessary. 8

• The duration of antibiotic treatment during pregnancy is commonly 10 days (44.4%) or 7 days (27.9%). 9
• Penicillin was occasionally prescribed at increased dosage (25.6%), while amoxicillin was sometimes administered at reduced dosages (42.5%). 9
• Dosages should be individualized according to pharmacokinetic information specific to pregnancy. 9

Common Pitfalls to Avoid

• Do not use Augmentin as routine first-line GBS prophylaxis when penicillin G or ampicillin alone would suffice. 2, 4
• Ensure at least 4 hours of IV antibiotics before delivery for adequate neonatal GBS protection. 4
• Do not assume all penicillin allergies are true IgE-mediated reactions; detailed allergy history can identify patients who can safely receive penicillin. 4
• For GBS bacteriuria detected during pregnancy, treatment of the acute UTI does NOT eliminate colonization, and intrapartum prophylaxis is still required during labor. 3

Bottom Line for Clinical Practice

IV amoxicillin-clavulanate is safe at 36 weeks pregnancy when indicated for specific infections requiring broader gram-negative coverage (such as complicated UTI, intra-abdominal infection, or chorioamnionitis), but should not replace penicillin G or ampicillin for routine GBS prophylaxis. 1, 2, 4 The choice should be guided by the specific infection being treated, local resistance patterns, and whether broader coverage beyond GBS is clinically necessary.