Urinary tract infections are common during pregnancy. The growing uterus slows the flow of urine by pressing against the tubes that connect the kidneys to the bladder or the ureters. This slow movement of urine is unable to wash down the bacteria which in turn can increase the risk of infection. But severe infections increase the risk of preterm labor and rupture of the membranes containing the fetus. Sometimes an infection in the bladder or ureters spreads up the urinary tract and reaches a kidney, causing an infection there. Antibiotic treatment can cure the problem completely.