Summary: Urinary tract infections (UTI) are more common during pregnancy than in non-pregnant women due to hormonal and mechanical changes in the urinary tract that cause urine stasis, in many of them accompanied by vesicoureteral reflux. Unlike in the general population, in pregnant women asymptomatic bacteriuria carries a considerable risk of UTI, with serious complications dangerous for both the mother and the unborn child, including pyelonephritis, urosepsis, preterm labor and low birth weight. Therefore all pregnant women should be screened for asymptomatic bacteriuria in the first trimester and treated if necessary. The paper briefly the principles of diagnosis, monitoring and appropriate antibiotic choices in pregnant women with asymptomatic bacteriuria and UTI.