Urinary tract infections (UTIs) are the most sparing infectious diseases that can cause dangerous infections. In the structure of extragenital pathology in prematurity they are also presented in the second place after diseases of the cardiovascular system. The problem of UTIs is due to the peculiarities of clinical courses, diagnosis and treatment of urinary tract infections during pregnancy. Asymptomatic bacteriuria (IBU), which is a preclinical form of UTI and is characterized by recurrent course, low proportion of self-healing, high choice of complications for mother and fetus.