Pregnancy and antibiotics

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Pregnancy and antibiotics

For UTI, use nitrofurantoin prescribe as 50 mg QID for 7 days.1 However, avoid in patients who are ≥ 36 weeks gestation (risk of neonatal hemolysis) or those with creatinine clearance < 60 mL/min.1 Alternatives are trimethoprim (after the first 3 months) and amoxicillin (both only if directed by culture results) or cefalexin; 500 mg BD for 7 days.1

Asymptomatic bacteriuria (growth of greater than 105 cfu/mL) or Group B strep on urine culture can be treated with amoxil or cefalexin and then give penicillin prophylactically at time of delivery.2
For bacterial vaginosis: metronidazole can be used but not ornidazole.1
For pertussis, azithromycin is the preferred macrolide.1
Antibiotics to avoid include amoxycillin with clavulanate, quinolones (norfloxacin and ciprofloxacin), tetracyclines (including doxycycline) trimethoprim in first trimester and co-trimoxazole.1


  1. NZ Formulary View here
  2. Prevention of Early-onset Neonatal Group B Streptococcal Disease. Green-top Guideline No. 36. BJOG (2017). View here

Gems are chosen by the Goodfellow director Dr. Bruce Arroll to be either practice changing or practice maintaining. The information is educational and not clinical advice.

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As published in NZ Doctor 11/12/2019