Lower UTI in Pregnancy

Comments from Expert Advisory Group

  • Send mid-stream urine (MSU) for culture.
  • Nitrofurantion should be avoided after 36+0 weeks due to risk of neonatal haemolysis.
  • Refer to local resistance patterns for empiric therapy where available and refer to MSU results.
  • Amoxicillin has been removed from the empiric treatment table as it is not suitable for empirical treatment due to high rates of resistance and should only be prescribed when pathogen is confirmed to be sensitive to amoxicillin.
  • Review empirical treatment with results of MSU culture and susceptibility.
  • Trimethoprim should not be prescribed for pregnant patients with established folate deficiency, low dietary folate intake, or women taking other folate antagonists.
  • Note guidelines on Asymptomatic Bacteriuria in Pregnancy
  • If acute pyelonephritis is suspected, consider referral to hospital. Consider acute pyelonephritis / upper urinary tract infection (UTI) when there is:
    • Flank pain which radiates to the iliac fossa and suprapubic area.
    • General systemic disturbance with fever, rigors, vomiting.
    • Tenderness and guarding over the kidney.
    • Nausea and / or vomiting.


Drug Dose Duration Notes
1st choice options

Nitrofurantoin Immediate Release Capsules

50 mg every 6 hours

7 days


Avoid after 36+0 weeks due to risk of neonatal haemolysis.

Immediate / Prolonged Release should be stated on the prescription1





Nitrofurantoin Prolonged Release Capsules 100 mg every 12 hours 7 days
2nd choice option



500 mg every 8 hours

7 days


 Cephalosporins should not be used in severe penicillin allergy. 


Alternative (if resistance to the above agents is suspected or if adherence to the above treatment course would be particularly problematic)




3 g



Single dose



Fosfomycin should only be used after a careful risk benefit assessment. Data in pregnancy is limited but to date has not indicated teratogenicity. Manufacturer advises that Fosfomycin should only be used during pregnancy if clearly necessary.
Fosfomycin should ideally be taken at night, on an empty stomach, and empty bladder to maximise absorption and effectiveness.

*Seek specialist/microbiologist advice in case of severe penicillin allergy in pregnant patients if nitrofurantoin is not an option.

1Two nitrofurantoin formulations are available: nitrofurantoin immediate release capsules (Macrodantin®) and nitrofurantoin prolonged release capsules (MacroBid®). For the treatment of infection the prolonged release capsules are dosed twice daily whilst the standard capsules are dosed four times daily. These products are not interchangeable

Patient Information

Safe Prescribing (visit the safe prescribing page)

Reviewed June 2024

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