Impact of Maternal Urinary Tract Infections and Pathogen Eradication on Preterm Birth Risk: A Prospective Cohort Study

Abstract

Background:
Urinary tract infections (UTIs) are common during pregnancy and can induce systemic inflammatory cascades and uterine contractions, predisposing to preterm birth.
Objectives: To evaluate the risk of preterm birth associated with asymptomatic bacteriuria, acute cystitis, and gestational pyelonephritis in pregnant women.
Materials and methods: We conducted a prospective cohort study involving 410 pregnant women screened for UTIs in the first, second, and third trimesters. The incidence of preterm birth (< 37 weeks of gestation) was evaluated according to UTI subtype and response to antimicrobial therapy.
Results: Gestational UTI was diagnosed in 82 (20.0%) women (asymptomatic bacteriuria: 10.2%, acute cystitis: 6.8%, gestational pyelonephritis: 2.9%). The risk of preterm birth in women with UTIs was 18.3% (n = 15) compared with 6.7% (n = 22) in uninfected controls (OR = 3.11; 95% CI: 1.54–6.28; p = 0.001). Gestational pyelonephritis increased the preterm delivery risk 5.4-fold (95% CI: 1.82–16.01; p = 0.002). Successful antimicrobial eradication of asymptomatic bacteriuria reduced preterm birth risk to baseline population levels (p = 0.42).
Conclusions: Maternal urinary tract infections represent a significant, modifiable risk factor for preterm birth, reinforcing the necessity of routine screening and timely antimicrobial treatment.

Keywords:
Urinary Tract Infection, Asymptomatic Bacteriuria, Pyelonephritis, Preterm Birth, Pregnancy Outcomes.