What are safe antibiotics and antiemetics for pregnant women?

Safe Antibiotics and Antiemetics in Pregnancy

Safe Antibiotics: First-Line Agents

Amoxicillin and 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, 2

Penicillins (Preferred)

• Amoxicillin is classified as Category A/B and compatible throughout all trimesters and breastfeeding, with extensive human data showing no harm to the fetus at therapeutic doses 1, 2, 3
• Ampicillin is an acceptable alternative to penicillin, particularly for Group B Streptococcus prophylaxis 2
• Piperacillin-tazobactam is explicitly listed as compatible for use during pre-conception and first trimester 3
• All penicillins are considered low risk based on decades of clinical experience 3, 4

Cephalosporins (Preferred)

• Cephalexin (first-generation) has moderate-quality evidence supporting safety throughout pregnancy with no demonstrated fetal harm 1, 2, 3
• Cefazolin is the preferred agent for penicillin-allergic women without history of anaphylaxis 2
• Cefuroxime and ceftazidime are safe throughout pregnancy with no demonstrated fetal harm 2
• Cephalosporins are considered first-line agents with extensive safety data 4

Alternative Safe Options

• Azithromycin is considered a safe alternative for penicillin-allergic patients, though preliminary data remain insufficient for routine recommendation 3
• Erythromycin base 500 mg orally four times daily for 7 days is recommended for chlamydial infections in pregnancy 1, 3
• Clindamycin has moderate evidence supporting its safety with no significant risks of congenital anomalies or preterm delivery 3
• Metronidazole is considered safe during pregnancy and breastfeeding; if single 2g dose used during breastfeeding, stop feeding for 12-24 hours 1, 5

Antibiotics to STRICTLY AVOID

Tetracyclines (Contraindicated)

• Doxycycline and all tetracyclines should be avoided after the fifth week of pregnancy due to tooth discoloration, transient bone growth suppression, and potential maternal fatty liver of pregnancy 1, 2, 3, 6

Trimethoprim-Sulfamethoxazole (Contraindicated)

• Co-trimoxazole should be avoided, especially during the first trimester, due to increased risk of preterm birth, low birthweight, kernicterus, hyperbilirubinemia, and fetal hemolytic anemia 1, 2, 3
• If necessary during first trimester, supplement with 5 mg/day folic acid due to neural tube defect risk 3

Fluoroquinolones (Contraindicated)

• Ciprofloxacin and ofloxacin should be avoided due to potential fetal cartilage damage in animal studies 2, 3, 5

Aminoglycosides (Use Only if Life-Threatening)

• Gentamicin and tobramycin should be avoided if possible due to eighth cranial nerve toxicity and nephrotoxicity risk 2, 6
• Systematic use should be considered solely in life-threatening infections with gram-negative pathogens and/or treatment failure of recommended antibiotics 6

Other Agents to Avoid

• Erythromycin estolate is contraindicated during pregnancy due to drug-related hepatotoxicity 3
• Amoxicillin-clavulanate should be avoided in women at risk of preterm delivery due to very low risk of necrotizing enterocolitis in the fetus 2, 3

Infection-Specific Dosing 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 1, 2

Chlamydia

• Erythromycin base 500 mg orally four times daily for 7 days OR amoxicillin 500 mg orally three times daily for 7-10 days 1
• Azithromycin 1g single dose is preferable to 7-day erythromycin course 5

Chancroid

• Azithromycin 1-2g single dose OR ceftriaxone 250 mg intramuscularly 5

Trichomonas Vaginalis

• Metronidazole 500 mg twice daily for 7 days (earlier fears of teratogenesis have not been confirmed) 5

Bacterial Vaginosis (in high-risk women)

• Metronidazole 1 g/day orally for 5 days (treat only women with risk factors for preterm delivery) 5

Safe Antiemetics in Pregnancy

Note: The provided evidence does not contain specific information about antiemetics in pregnancy. Based on general medical knowledge, first-line safe antiemetics include:

• Pyridoxine (Vitamin B6) with or without doxylamine is considered first-line
• Ondansetron has extensive safety data though some studies suggest caution in first trimester
• Metoclopramide is generally considered safe
• Promethazine can be used but may cause sedation

Critical Clinical Pitfalls to Avoid

Mandatory Screening

• All pregnant women should be screened for asymptomatic bacteriuria and Group B Streptococcus at 35-37 weeks gestation 1, 2

Penicillin Allergy Considerations

• Penicillin-allergic patients with history of anaphylaxis, angioedema, respiratory distress, or urticaria should NOT receive penicillin, ampicillin, or cefazolin 2

Breastfeeding Monitoring

• Monitor all breastfed infants for gastrointestinal effects when mother receives antibiotics 1, 2
• Antibiotics in breast milk may cause falsely negative cultures if febrile infant requires evaluation 1, 2, 3

Drug Interactions

• Amoxicillin may affect intestinal flora, leading to reduced efficacy of combined oral estrogen/progesterone contraceptives 7
• Concurrent use with oral anticoagulants may result in abnormal prolongation of prothrombin time (increased INR); appropriate monitoring required 7

Test of Cure

• Both test of cure and re-testing after several weeks are advisable in most pregnant patients with STDs because partner notification and treatment are likely less efficient during pregnancy 5