To determine the rates of urinary incontinence in a racially diverse, tertiary care obstetrical population during the third trimester and postpartum using a validated symptom-screening questionnaire. Third trimester prenatal patients receiving obstetric care at Loyola University Medical Center between March and November 2003 participated in this prospective study approved by the Institutional Review Board. Third-trimester participants completed the 15-item, validated Medical, Epidemiological, and Social Aspects of Aging (MESA) questionnaire and the Hunskaar Severity Index. The MESA was readministered to participants during a 6- to 8-week postpartum visit. One hundred and thirteen women completed antenatal and postpartum MESAs. Seventy-four percent (83 of 113) of the patients in the third trimester were categorized as incontinent. The postpartum incontinence rates decreased to 44% (50 of 113). Twenty-one percent (24 of 113) of the participants after delivery reported pure stress incontinence, 3% (3 of 113) urge incontinence, and 20% (23 of 113) mixed incontinence. Only 4% (5 of 113) of the women developed de novo incontinence postpartum: three reported symptoms of pure stress incontinence and two reported symptoms consistent with urge incontinence. The MESA questionnaire identifies more women with antenatal and postpartum urinary incontinence than currently described in the literature.