What antibiotics are recommended during pregnancy?

Recommended Antibiotics During Pregnancy

Penicillins and cephalosporins are the safest antibiotic classes during pregnancy and should be used as first-line treatments when indicated. 1

Safe First-Line Antibiotics in Pregnancy

Penicillins

• Amoxicillin: 500 mg orally three times daily for 7 days 1, 2
  • FDA Pregnancy Category B
  • First-line for dental, respiratory, and urinary tract infections
  • Safe throughout all trimesters

Cephalosporins

• Cefazolin: 2g IV initial dose, then 1g IV every 8 hours until delivery 3
  • Preferred alternative for penicillin-allergic patients without history of anaphylaxis
  • Safe for intrapartum prophylaxis

Safe Alternative Antibiotics

• Azithromycin: 1g orally as a single dose 1

  • Particularly useful for chlamydial infections
  • Alternative for streptococcal pharyngitis

• Erythromycin base: 500 mg orally four times a day for 7 days 3

  • Recommended for chlamydial infections in pregnancy
  • Alternative: Erythromycin ethylsuccinate 800 mg orally four times a day for 7 days

• Clindamycin: 900 mg IV every 8 hours until delivery 3, 1

  • For penicillin-allergic patients with high risk for anaphylaxis
  • Only if isolate is susceptible to clindamycin and erythromycin

• Spiramycin: 1g (3 million IU) orally three times daily 3

  • Specifically for toxoplasmosis in pregnancy
  • Available in the US only through FDA's Investigational New Drug process

Antibiotics to Avoid During Pregnancy

• Tetracyclines (including doxycycline): Contraindicated due to risk of tooth discoloration and bone growth inhibition 1, 4

• Fluoroquinolones: Contraindicated due to risk of cartilage damage 1, 4, 5

• Trimethoprim-sulfamethoxazole: Associated with increased risk of birth defects 1, 6

• Aminoglycosides: Should be avoided due to risk of ototoxicity and nephrotoxicity 1, 4

Special Considerations

For Penicillin-Allergic Patients

1. Without history of anaphylaxis, angioedema, respiratory distress, or urticaria:

   • Use cefazolin 3

2. With history of anaphylaxis or severe reactions:

   • Order susceptibility testing for clindamycin and erythromycin 3
   • If susceptible, use clindamycin 900 mg IV every 8 hours
   • If not susceptible or results unavailable, use vancomycin 1g IV every 12 hours until delivery 3

For Specific Infections

Group B Streptococcus Prophylaxis

• First-line: Penicillin G, 5 million units IV initial dose, then 2.5-3.0 million units every 4 hours until delivery 3
• Alternative: Ampicillin, 2g IV initial dose, then 1g IV every 4 hours until delivery 3

Chlamydial Infection

• Recommended: Erythromycin base 500 mg orally four times a day for 7 days 3
• Alternative: Amoxicillin 500 mg orally three times a day for 7 days 3
• Alternative: Azithromycin 1g orally in a single dose (preliminary data indicate safety) 3

Toxoplasmosis

• For negative AF PCR test: Spiramycin 1g (3 million IU) orally three times daily until delivery 3
• For documented fetal infection: Pyrimethamine + sulfadiazine + folinic acid 3

Important Clinical Pearls

1. Physiological changes in pregnancy (increased GFR, total body volume, enhanced cardiac output) may require dose adjustments 6

2. Test of cure is recommended 3 weeks after treatment completion, especially for chlamydial infections 3, 5

3. Partner treatment is essential to prevent reinfection 3, 5

4. Erythromycin estolate is contraindicated during pregnancy due to drug-related hepatotoxicity 3

5. Duration of treatment may often be shorter than in non-pregnant patients - 7-10 days is typically sufficient for most infections 7

By following these guidelines and selecting appropriate antibiotics based on the specific infection and patient factors, clinicians can effectively treat infections during pregnancy while minimizing risks to both mother and fetus.