What is the first line antibiotic for a urinary tract infection (UTI) during pregnancy?

From the Guidelines

Nitrofurantoin is the first-line antibiotic for treating uncomplicated urinary tract infections during pregnancy, typically prescribed as 100 mg twice daily for 5 days. According to the European Association of Urology guidelines on urological infections, published in 2024 1, nitrofurantoin macrocrystals or monohydrate are recommended as first-line treatment options. The guidelines suggest a daily dose of 50–100 mg four times a day or 100 mg twice daily for 5 days.

• Key considerations for treating UTIs during pregnancy include:
  • Effectiveness against common UTI pathogens like E. coli
  • Safety profile for both mother and fetus
  • Avoiding certain antibiotics during specific trimesters due to potential risks
• Other options like fosfomycin trometamol, given as a single 3-gram dose, may be considered in certain situations, but nitrofurantoin remains the preferred first-line choice due to its efficacy and safety profile, as supported by the 2024 guidelines 1.
• It is crucial for pregnant women to complete the full course of antibiotics, even if symptoms improve quickly, and to stay hydrated by drinking plenty of water. If symptoms worsen or do not improve within 48 hours, patients should notify their healthcare provider, as untreated UTIs can lead to serious complications such as pyelonephritis and increased risk of preterm labor.

From the FDA Drug Label

CLINICAL STUDIES Controlled clinical trials comparing nitrofurantoin monohydrate/macrocrystals capsules 100 mg p.o. q12h and nitrofurantoin macrocrystals 50 mg p.o. q6h in the treatment of acute uncomplicated urinary tract infections demonstrated approximately 75% microbiologic eradication of susceptible pathogens in each treatment group. The first line antibiotic for a urinary tract infection during pregnancy is nitrofurantoin 2.

• Nitrofurantoin is used for the treatment of acute uncomplicated urinary tract infections.
• The drug has shown approximately 75% microbiologic eradication of susceptible pathogens.

From the Research

First Line Antibiotic for Urinary Tract Infection During Pregnancy

• The first line antibiotic for a urinary tract infection (UTI) during pregnancy is not universally agreed upon, but several options are recommended based on various studies 3, 4, 5, 6, 7.
• According to a study published in 1994, amoxicillin 500 mg tid for three days is recommended for symptomatic UTI in pregnancy 3.
• Another study from 1992 suggests that postcoital prophylaxis with a single oral dose of either cephalexin (250 mg) or nitrofurantoin macrocrystals (50 mg) can be effective in preventing recurrent UTIs during pregnancy 4.
• A 2012 systematic review found that a daily dose of nitrofurantoin and close surveillance did not prevent recurrent UTI compared to close surveillance alone, but significantly reduced asymptomatic bacteriuria in women with high clinic attendance rates 5.
• A 2022 systematic review and meta-analysis compared the efficacy and safety of fosfomycin and nitrofurantoin for the treatment of uncomplicated lower UTI in women, and found no significant differences in clinical and microbiological cure rates, but more adverse events with fosfomycin 6.
• A 2010 Cochrane review found that different antibiotic regimens for treating asymptomatic bacteriuria in pregnancy had varying results, and no definitive conclusion could be drawn on the most effective and safest antibiotic regimen 7.

Key Findings

• Amoxicillin, cephalexin, and nitrofurantoin are potential first line antibiotic options for UTI during pregnancy.
• The choice of antibiotic may depend on factors such as local availability, cost, and side effects.
• More research is needed to determine the optimal antibiotic regimen for preventing recurrent UTI in pregnant women.