From the Guidelines
Nitrofurantoin is the recommended first-line antibiotic for treating urinary tract infections (UTIs) during pregnancy, specifically 100 mg twice daily for 5 days, as it is safe and effective in this context. According to the European Association of Urology guidelines on urological infections, published in 2024 1, nitrofurantoin macrocrystals are a suggested antimicrobial therapy regimen for uncomplicated cystitis in women. The guidelines provide various options for treating UTIs, including:
- Fosfomycin trometamol (3 g single dose) for uncomplicated cystitis in women
- Nitrofurantoin macrocrystals (50–100 mg four times a day or 100 mg twice daily) for 5 days
- Pivmecillinam (400 mg three times a day) for 3–5 days
- Cephalosporins (e.g., cefadroxil) (500 mg twice daily) for 3 days, if the local resistance pattern for Escherichia coli is <20%
It's essential to note that some antibiotics, such as trimethoprim and trimethoprim-sulfamethoxazole, have restrictions during pregnancy 1. Trimethoprim should be avoided in the first trimester, while trimethoprim-sulfamethoxazole should not be used in the last trimester. Pregnant women should always consult their healthcare provider to determine the best course of treatment for their specific situation.
From the FDA Drug Label
- 1 Pregnancy Teratogenic Effects: Reproduction studies have been performed in mice and rats at doses up to 2000 mg/kg (3 and 6 times the 3 g human dose, based on body surface area). There was no evidence of harm to the fetus due to amoxicillin. There are, however, no adequate and well-controlled studies in pregnant women Because animal reproduction studies are not always predictive of human response, amoxicillin should be used during pregnancy only if clearly needed.
Amoxicillin can be used during pregnancy if clearly needed, as there is no evidence of harm to the fetus in animal studies, but no adequate and well-controlled studies have been conducted in pregnant women 2.
From the Research
Safe Antibiotics for UTIs during Pregnancy
The following antibiotics are considered safe for treating urinary tract infections (UTIs) during pregnancy:
- Nitrofurantoin: This antibiotic has been used for over 35 years to treat UTIs, including asymptomatic bacteriuria of pregnancy, and is considered safe for use during pregnancy 3, 4, 5.
- Cephalexin: This antibiotic has been shown to be effective in preventing recurrent UTIs during pregnancy and is considered a safe option 4.
- Amoxicillin: This antibiotic has been recommended for the treatment of symptomatic UTIs during pregnancy, with a cure rate of approximately 80% 6.
- Trimethoprim/sulfamethoxazole: This antibiotic combination has been shown to provide cure rates of greater than 80% for UTIs during pregnancy, but its use is recommended with caution due to potential risks associated with sulfonamides 7, 6.
- Fosfomycin: This antibiotic has been found to be effective and safe for the treatment of uncomplicated UTIs in women, including those who are pregnant 5.
Considerations for Antibiotic Use during Pregnancy
When treating UTIs during pregnancy, it is essential to consider the potential risks and benefits of antibiotic use. The American College of Obstetricians and Gynecologists (ACOG) recommends that sulfonamides and nitrofurantoin may be prescribed in the first trimester of pregnancy only when other antimicrobial therapies are deemed clinically inappropriate 7. Additionally, women's health care providers should be familiar with the ACOG recommendations and consider the possibility of early pregnancy when treating women of reproductive age 7.