The Risk of Preterm Birth in Low Risk Pregnant Women with Urinary Tract Infections

Objective Urinary tract infections are among the most common infections during pregnancy. The association between symptomatic lower urinary tract infections during pregnancy and fetal and maternal complications such as preterm birth and low birthweight remains unclear. The aim of this research is to evaluate the association between urinary tract infections during pregnancy and maternal and neonatal outcomes, especially preterm birth. Study Design This study is a secondary analysis of a multicenter prospective cohort study, which included patients between October 2011 and June 2013. The population consists of women with low risk singleton pregnancies. We divided the cohort into women with and without a symptomatic lower urinary tract infection after 20 weeks of gestation. Baseline characteristics and maternal and neonatal outcomes were compared between the two groups. Multivariable logistic regression analysis was used to correct for confounders. The main outcome was spontaneous preterm birth at <37 weeks. Results We identified 4,918 pregnant women eligible for enrollment, of whom 9.4% had a symptomatic lower urinary tract infection during their pregnancy. Women with symptomatic lower urinary tract infections were at increased risk for both preterm birth in general (12 vs. 5.1%, adjusted OR 2.5; 95% CI 1.7-3.5) as well as a spontaneous preterm birth at <37 weeks (8.2 vs. 3.7%, adjusted OR 2.3; 95% CI 1.5-3.5). This association was also present for early preterm birth at <34 weeks. Women with symptomatic lower urinary tract infections during pregnancy are also at increased risk of endometritis (8.9 vs. 1.8%, adjusted OR 5.3; 95% CI 1.4-20) and mastitis (7.8 vs. 1.8%, adjusted OR 4.0; 95% CI 1.6-10) postpartum. Conclusion Low risk women with symptomatic lower urinary tract infections during pregnancy are at increased risk of spontaneous preterm birth. In addition, an increased risk for endometritis and mastitis postpartum was found in women with symptomatic lower urinary tract infection during pregnancy. Key Points UTIs increase the risk of preterm birth. UTIs increase the risk of endometritis postpartum. UTIs increase the risk of mastitis postpartum.