Treatment of Uncomplicated UTIs in Pregnant Women
For uncomplicated urinary tract infections in pregnant women, obtain a urine culture and treat with nitrofurantoin (100 mg twice daily for 5 days), fosfomycin trometamol (3 g single dose), or a first-generation cephalosporin, avoiding trimethoprim in the first trimester and trimethoprim-sulfamethoxazole in the last trimester. 1
Diagnostic Approach
Urine culture is mandatory in all pregnant women with suspected UTI, unlike non-pregnant women where empiric treatment based on symptoms alone may be acceptable 1. This is critical because:
- Pregnancy itself is a risk factor requiring culture confirmation before treatment 1
- Untreated UTIs in pregnancy carry significant risks of ascending infection and complications for both mother and fetus 2
- Asymptomatic bacteriuria must be identified and treated in pregnancy (unlike non-pregnant women) to prevent progression to pyelonephritis 1, 3
First-Line Antibiotic Options
The 2024 European Association of Urology guidelines provide specific pregnancy-safe options from their general cystitis recommendations 1:
Preferred Agents:
- Nitrofurantoin: 100 mg twice daily for 5 days (macrocrystals or monohydrate formulations) 1, 2
- Fosfomycin trometamol: 3 g single dose 1, 2
- First-generation cephalosporins (e.g., cephalexin): 500 mg twice daily for 3-7 days 3
Important Trimester-Specific Restrictions:
- Trimethoprim: Contraindicated in first trimester (teratogenic risk) 1
- Trimethoprim-sulfamethoxazole: Contraindicated in last trimester (risk of neonatal hyperbilirubinemia and kernicterus) 1
Treatment Duration
Standard treatment duration is 5-7 days for symptomatic UTI in pregnancy 2, 4. While single-dose therapy has been studied with amoxicillin (showing approximately 80% cure rates), three-day regimens are generally preferred for symptomatic infections to ensure adequate treatment 4.
Post-Treatment Monitoring
Obtain repeat urine culture 7 days after completing therapy to document microbiological cure 4. This is essential in pregnancy because:
- Treatment failure requires prompt identification 4
- Persistent bacteriuria increases risk of pyelonephritis 3
- Recurrent infections may require suppressive prophylaxis throughout pregnancy 3
Special Considerations for Pyelonephritis
If the pregnant patient presents with fever, flank pain, or systemic symptoms suggesting pyelonephritis:
- Hospitalization with intravenous antibiotics is indicated 5
- Second or third-generation cephalosporins (ceftriaxone 1-2 g daily or cefotaxime 2 g three times daily) are preferred initial therapy 1, 3
- Use ultrasound or MRI (not CT) for imaging if complications are suspected to avoid fetal radiation exposure 1
Critical Pitfalls to Avoid
- Never use fluoroquinolones in pregnancy—they are teratogenic and contraindicated despite being first-line in non-pregnant women 1
- Avoid ampicillin monotherapy due to high E. coli resistance rates (>20% in most regions) 3
- Do not treat asymptomatic bacteriuria without culture confirmation, but once confirmed, treatment is mandatory in pregnancy (unlike non-pregnant patients) 1
- Screen all pregnant women for bacteriuria routinely with urine culture, as untreated asymptomatic bacteriuria progresses to pyelonephritis in 20-40% of cases 3