What are safe antibiotics and anti-emetics (anti-emetic medications) for pregnant women?

Safe Antibiotics and Anti-Emetics in Pregnancy

Safe Antibiotics in Pregnancy

Penicillins (particularly amoxicillin) and cephalosporins (particularly cephalexin) are the safest first-line antibiotics for pregnant women, with decades of clinical experience demonstrating no teratogenic effects and compatibility throughout all trimesters and during breastfeeding. 1

First-Line Safe Antibiotics

• Penicillins are the preferred agents throughout pregnancy, with amoxicillin classified as Category A/B and compatible in all trimesters 2, 1
• Ampicillin is an acceptable alternative to penicillin, particularly for Group B Streptococcus prophylaxis (2 g IV initial dose, then 1 g IV every 4 hours until delivery) 2
• Cephalosporins (cephalexin, cefuroxime, ceftazidime) are safe throughout pregnancy with no demonstrated fetal harm 2, 1, 3
• Cefazolin is the preferred agent for penicillin-allergic women without history of anaphylaxis (2 g IV initial dose, then 1 g IV every 8 hours) 2
• Erythromycin is probably safe and can be used when penicillins are contraindicated 2
• Azithromycin is probably safe (Category B1) but carries very low risk of hypertrophic pyloric stenosis if used during first 13 days of breastfeeding 2

Second-Line Antibiotics (Use with Caution)

• Clindamycin (900 mg IV every 8 hours) is acceptable for penicillin-allergic women at high risk for anaphylaxis if isolate is susceptible 2, 4
• Vancomycin (1 g IV every 12 hours) should be reserved for penicillin-allergic women at high risk for anaphylaxis when susceptibility testing unavailable 2
• Metronidazole is possibly safe but should only be used if no safer alternatives exist; if single 2 g oral dose used during breastfeeding, stop feeding for 12-24 hours 2, 1

Antibiotics to AVOID

• Tetracyclines (doxycycline) should be avoided after the fifth week of pregnancy due to tooth discoloration, transient bone growth suppression, and potential maternal fatty liver 2, 1
• Trimethoprim-sulfamethoxazole (co-trimoxazole) should be avoided, especially during first trimester, due to increased risk of preterm birth, low birthweight, kernicterus, hyperbilirubinemia, and fetal hemolytic anemia 2, 1
• Fluoroquinolones (ciprofloxacin) should be avoided due to potential fetal cartilage damage in animal studies 2
• Aminoglycosides (gentamicin, tobramycin) should be avoided if possible due to eighth cranial nerve toxicity and nephrotoxicity risk; only use for severe infections when other antibiotics have failed 2

Infection-Specific Recommendations

• Group B Streptococcus prophylaxis: Penicillin G 5 million units IV initially, then 2.5-3.0 million units IV every 4 hours until delivery 2, 1
• Endocarditis treatment: Penicillin, ampicillin, amoxicillin, erythromycin, mezlocillin, and cephalosporins can all be given during all trimesters 2

Anti-Emetics in Pregnancy

Note: The provided evidence does not contain specific guideline or drug label information about anti-emetic medications safe in pregnancy. Based on general medical knowledge, the following are commonly used:

Generally Safe Anti-Emetics

• Vitamin B6 (pyridoxine) with or without doxylamine is first-line for nausea and vomiting of pregnancy
• Ondansetron is commonly used but should be discussed with obstetric provider
• Metoclopramide is generally considered safe
• Promethazine can be used but may cause sedation

Critical Clinical Pitfalls

• Screen all pregnant women for asymptomatic bacteriuria and Group B Streptococcus at 35-37 weeks gestation 1
• Monitor breastfed infants for gastrointestinal effects when mother receives antibiotics 1
• Antibiotics in breast milk may cause falsely negative cultures if febrile infant requires evaluation 2, 1
• Penicillin-allergic patients with history of anaphylaxis, angioedema, respiratory distress, or urticaria should NOT receive penicillin, ampicillin, or cefazolin 2
• Amoxicillin-clavulanic acid is not recommended in women at risk of pre-term delivery due to very low risk of necrotizing enterocolitis in the fetus 2