What is the recommended treatment for a Urinary Tract Infection (UTI) in a pregnant woman?

Treatment of UTI in Pregnant Women

Pregnant women with UTI should receive antibiotic therapy with nitrofurantoin, fosfomycin trometamol, or cephalosporins as first-line agents, with treatment duration of 3-7 days depending on the specific antibiotic chosen. 1

Diagnostic Approach

• Obtain a urine culture before starting antibiotics in all pregnant women with suspected UTI, as this is specifically recommended for this population 1
• Screen for asymptomatic bacteriuria in early pregnancy (12-16 weeks) with urine culture, as untreated bacteriuria increases risk of pyelonephritis from approximately 20-30% to 1-4% with treatment 1
• Dipstick testing alone has low sensitivity (~50%) and should not replace urine culture in pregnant women 1

First-Line Antibiotic Options

Nitrofurantoin 1, 2, 3:

• Nitrofurantoin macrocrystals 50-100 mg four times daily for 5 days, OR
• Nitrofurantoin monohydrate/macrocrystals 100 mg twice daily for 5 days
• Avoid in the first trimester when other options are available due to potential risk of birth defects, per ACOG recommendations 4
• Generally considered safe in second and third trimesters 3

Fosfomycin trometamol 1, 2, 3:

• Single 3-gram dose
• Particularly convenient for asymptomatic bacteriuria or uncomplicated cystitis
• Safe throughout pregnancy 3

Cephalosporins 1, 2, 5:

• Cefadroxil 500 mg twice daily for 3 days, OR
• Cefixime (third-generation cephalosporin) - dosing per local protocols
• Safe and effective throughout pregnancy 3

Amoxicillin 5:

• 500 mg three times daily for 3 days
• Cure rates approximately 80% with single-dose therapy, higher with 3-day courses 5

Alternative Agents (Use with Caution)

Trimethoprim-sulfamethoxazole 1:

• 160/800 mg twice daily for 3 days
• Avoid in first trimester (risk of neural tube defects) 1, 4
• Avoid in last trimester (risk of kernicterus) 1
• May be used in second trimester if other options are unsuitable 1

Treatment Duration

• Standard duration: 3-7 days depending on the antibiotic chosen 1, 5
• Single-dose fosfomycin is acceptable for uncomplicated cases 1
• A Cochrane review found insufficient evidence to definitively recommend optimal duration, but 3-7 day regimens are standard practice 1

Critical Management Points

Post-Treatment Follow-Up 1, 5:

• Repeat urine culture 1-2 weeks after completing therapy to confirm eradication
• This is essential in pregnancy due to high risk of complications from persistent infection 1

Avoid These Antibiotics 4, 3:

• Fluoroquinolones (ciprofloxacin): Associated with musculoskeletal abnormalities, despite being commonly prescribed 4, 3
• Tetracyclines: Risk of tooth discoloration and bone growth abnormalities 3
• Sulfonamides in first trimester: Risk of birth defects including anencephaly and heart defects 4

Asymptomatic Bacteriuria

• Screen and treat asymptomatic bacteriuria in all pregnant women with standard short-course treatment or single-dose fosfomycin 1
• This is one of the few populations where treating asymptomatic bacteriuria is strongly indicated, as it prevents pyelonephritis and preterm labor 1
• Treatment reduces pyelonephritis risk from 20-35% to 1-4% 1

Recurrent UTI Prevention in Pregnancy

For pregnant women with history of recurrent UTIs 6:

• Post-coital prophylaxis with either cephalexin 250 mg or nitrofurantoin 50 mg as single dose after intercourse is highly effective 6
• This approach reduced UTI incidence from 130 infections in 7 months pre-prophylaxis to only 1 infection during 39 pregnancies 6

Common Pitfalls to Avoid

• Do not rely on dipstick alone - always obtain culture in pregnant women 1
• Do not use nitrofurantoin or sulfonamides in first trimester unless no alternatives exist 4
• Do not skip post-treatment culture - confirmation of cure is essential in pregnancy 1, 5
• Do not prescribe fluoroquinolones despite their common use - they carry unnecessary fetal risks 4, 3
• Do not treat for longer than 7 days for uncomplicated UTI - this promotes resistance without added benefit 1