OBJECTIVE: To describe the prevalence and severity of urinary incontinence in the 12-month postpartum period and to relate this incontinence to several potential risk factors including body mass index, smoking, oral contraceptives, breast-feeding, and pelvic floor muscle exercise. METHODS: Participants were 523 women, aged 14 to 42 years, who had obstetrical deliveries. The women were interviewed in their rooms on postpartum day 2 or 3 and by telephone 6 weeks, 3 months, 6 months, and 12 months postpartum. Chart abstraction was conducted to obtain obstetrical data from the index delivery. RESULTS: At 6 weeks postpartum, 11.36% of women reported some degree of urinary incontinence since the index delivery. Although the rate of incontinence did not change significantly over the postpartum year, frequency of accidents decreased over time. In the generalized estimating equation, postpartum incontinence was significantly associated with seven variables: baseline report of smoking (odds ratio [OR] 2.934; P =.002), incontinence during pregnancy (OR 2.002; P =.007), length of breast-feeding (OR 1.169; P =.023), vaginal delivery (OR 2.360; P =.002), use of forceps (OR 1.870; P =.024), and two time-varying covariates: frequency of urination (OR 1.123; P = <.001) and body mass index (OR 1.055; P =.005). Factors not associated with postpartum incontinence included age, race, education, episiotomy, number of vaginal deliveries, attendance at childbirth preparation classes, and performing pelvic floor muscle exercises during the postpartum period. CONCLUSION: Postpartum incontinence is associated with several risk factors, some of which are potentially modifiable and others that can help target at-risk women for early intervention.