Urinary tract infections are common complications of pregnancy; upper tract infections in particular may lead to significant morbidity for both the mother and fetus. Bacteriuria is a significant risk factor for developing pyelonephritis in pregnant women. Therefore, proper screening and treatment of bacteriuria during pregnancy is necessary to prevent complications. All women should be screened for bacteriuria in the first trimester, and women with a history of recurrent urinary tract infections or anomalies should have repeat bacteriuria screening throughout pregnancy. Treatment of bacteriuria should include 3-day therapy with appropriate antimicrobials, and women should be followed closely after treatment because recurrence may occur in up to one third of patients.