Maternal urinary tract infections in pregnancy showed an association with a higher rate of preterm birth in previous studies. The aim of this study was to check this relationship, and in addition to evaluate the efficacy of recent medical treatments. The population-based large control (without any defects) data set of the Hungarian Case-Control Surveillance System of Congenital Abnormalities was evaluated. Of 38,151 newborn infants, 2188 (5.7%) had mothers with urinary tract infections during pregnancy, and 90% of these maternal diseases were prospectively and medically recorded. The prevalence of pre-eclampsia and polyhydramnios showed an association with urinary tract infections during pregnancy. Pregnant women with urinary tract infections in pregnancy had a somewhat shorter gestational age (0.1 week) and a higher proportion of preterm births (10.4% vs 9.1%). These differences were correlated with the severity of urinary tract infections. However, the preterm-inducing effect of maternal urinary tract infections is preventable by some antimicrobial drugs such as ampicillin, cefalexin and cotrimoxazole. In conclusion, maternal urinary tract infections during pregnancy increase pre-eclampsia and polyhydramnios, and in addition the rate of preterm birth; however, the latter is preventable by appropriate drug treatments.