UTIs during pregnancy are a common cause of serious maternal and perinatal morbidity. Pregnancy-related physiological changes increases risk of UTI, which more frequently progresses to pyelonephritis. We aimed to examine the common etiology of UTI in obstetrics and its correlation with the age of patients. A total of 300 urine samples were collected from obstetric patients at their third trimester of pregnancy attended at an urban hospital in Dhaka, Bangladesh. Mid stream urine samples were processed for culture. Isolates were identified and antimicrobial drug susceptibility was found out. Obstetric patients had higher prevalence of UTI, found in 23% of the patients in the study. Among the UTI cases, 59% developed purulent infection. Pregnancies in both lower and higher age are more vulnerable to UTI infections. Mostly isolated etiological agents were E. coli and Klebsiella spp. among the Gram negative bacteria. Staphylococcus spp. and Enterococcus spp. were isolated among the Gram positive bacteria. Candida spp. were also isolated in a significant number of cases. The prevalence of UTI cases and the etiological agents varied with the age of patients; E. coli was found prevalent in younger patients which markedly declined in patients aged above 33 years. The occurrence of Candida spp. increased in older age. The prevalence as well as associated etiological agent of UTI in obstetric patients was found to have strong correlation with the age. Both the lower and higher age groups are more vulnerable to UTI and the later had the most versatile etiology.