Objective: In this study was designed to see the risk factors of UTI in pregnant women and the maternal and perinatal outcome. Methods: In this case control study, women enrolled in antenatal OPD of North East Medical College and Hospital, Sylhet, during July 2020 to December 2020, were randomly allocated into case and control group. The inclusion criteria for pregnant women during the 13th - 26th weeks of pregnancy in the case group was the positive urine cultures of bacteria (more than 10 5 colonies growth in a standard positive urine culture). The same with negative culture was control group. Then parameters such as parity, sexual activity, type of delivery, and infants' birth weight were recorded in questionnaire. Results: Incidence of UTI in mid trimester pregnancy during study period was 26%. Risk factors like previous history of UTI, sexual activity and multipara were higher in case group. Highest age incidence was between 20-30 years. Predominantly patients were asymptomatic. Lower abdominal pain was a common symptom. Eshcherichia coli was commonest organism. Prevalence of bacteriuria was more in women with history of UTI earlier in pregnancy. Premature rupture of membrane was significantly higher in case group. Caesarean section was higher in the case group. According to this study, the average weight of newborns whose mothers had UTI was 2.83 kg and it was 0.44 kg lower than the newborns of healthy mothers. Conclusion: According to the conducted study, UTI in mothers is the major reason for comparatively lower birth weight of infants. Routine urine check during pregnancy is helpful in diagnosing this early and fast care. For better results, more analysis is required.