Objective. To investigate the efficiency of using cranberry (Oxycoccus) extract capsules in pregnant women with urinary tract infections and to assess the frequency of disease exacerbations, perinatal outcomes, and the efficiency of the preparation for pregnancy-induced edemas. Subjects and methods. The investigation enrolled 195 pregnant women aged 20 to 44 years in the first and second trimesters after an infection exacerbation or asymptomatic bacteriuria identified by urinalysis. The women were proposed to take one capsule containing cranberry extract (phytolysin prenatal) thrice daily during antibiotic therapy and then one capsule once daily for 28-30 days. Results. There was term labor in 188 (96.4%), premature birth in 2 (1%), and late miscarriage at 21–22 weeks’ gestation in 1 (0.5%) patient with type 1 diabetes mellitus and fetal congenital malformations. Eleven (5.6%) of the 195 women taking cranberry extract capsules were found to have adverse reactions: heartburn (n = 6 (3.1%)) gastric pain (n = 4 (2.1%)), nausea/vomiting (n = 1 (0.5%)), and diarrhea (n = 1 (0.5%)). With the use of phytolysin prenatal, there was a reduction of edema in the lower extremities, hands, and face. Conclusion. The clinical research covering 195 pregnant women with urinary tract diseases confirmed the efficacy of cranberry extract in preventing urinary tract infection exacerbations during pregnancy. Rare side effects confirmed the safety of the agent. Phytolysin prenatal may also be recommended for pregnant women with edemas. © Bionika Media Ltd.