Nitrofurantoin Safety in Pregnancy for Lower UTI Treatment

Recommended Dosing and Duration

The American College of Obstetricians and Gynecologists recommends nitrofurantoin monohydrate/macrocrystals 100 mg twice daily for 5 days as the guideline-recommended regimen for treating lower UTIs during pregnancy, with a strength of evidence based on clinical guidelines 1, 2
The standard treatment duration is 7-14 days for pregnant women to ensure complete eradication, though 5-day courses have been studied, with a moderate strength of evidence 3, 2

Nitrofurantoin is recommended as first-line therapy for UTIs in the first trimester, with a high strength of evidence 3, 2
The use of nitrofurantoin reduces pyelonephritis risk from 20-35% to 1-4% when bacteriuria is treated, with a moderate to high strength of evidence 3, 2
Nitrofurantoin must be avoided after 37 weeks gestation due to the theoretical risk of neonatal hemolytic anemia in G6PD-deficient newborns, with a high strength of evidence 3

The Infectious Diseases Society of America recommends cephalexin 500 mg four times daily for 7-14 days as a first-line alternative when nitrofurantoin is contraindicated, with a moderate strength of evidence 3
Fosfomycin 3g single dose is also an acceptable alternative, although with limited data, and a low to moderate strength of evidence 3, 2

Untreated bacteriuria increases pyelonephritis risk 20-30 fold, with a high strength of evidence 3, 2
Treatment reduces premature delivery and low birth weight, with a moderate strength of evidence 3
Even asymptomatic bacteriuria must be treated in pregnancy, with a high strength of evidence 3, 2

The American College of Obstetricians and Gynecologists recommends obtaining urine culture before treatment to guide therapy, with a high strength of evidence 3, 2
Follow-up culture 1-2 weeks after completion is necessary to confirm cure, with a moderate strength of evidence 3