Objective To investigate the current status of urinary incontinence (UI) at the third trimester of pregnancy among primiparas in Guangdong Province.Methods The convenience sampling method was adopted to conduct the retrospective analysis on 714 primiparas in 3 hospitals of Guangdong Province from June 2015 to March 2016.International Consultation on Incontinence Questionnaire Urinary Incontinence Short-Form Chinese was used to investigate the occurrence status of UI at the third trimester of pregnancy among primiparas.And its influencing factors were analyzed.Results Among 714 primiparas,192 cases (26.9％) developed UI during the third trimester of pregnancy,in which stress UI accounted for 67.2％ (129/192).The prepregnancy BMI and abortion had statistical difference between.the UI patients and non-UI patients (P＜0.05).The multivariate Logistic regression results showed that pre-pregnancy BMI was correlated with UI at the trimester stage of pregnancy (OR =1.077,P＜0.05).Conclusion Pre-pregnancy BMI might be an independent risk factor of UI occurrence at the third trimester of pregnancy.