Material and Method: The present study population comprised ≥36 weeks singleton pregnant women attending the ANC at King Chulalongkorn Memorial Hospital between 2009 and 2010. Questionnaire was developed from International Continence Society Questionnaire, which consisted of two parts, (1) socioeconomic demographic, characteristics related to UI, and (2) obstetric characteristic, UI experienced after delivery. Validity and reliability of the questionnaire were tested (Cronbach’s alpha = 0.8). Chi-square, t-test, Pearson correlation McNemar test, and Binary logistic regression were used for comparison.

Results: The majority of the participants (93.8%) were aged between 20 and 39 years old. The prevalence of UI during late pregnancy and three months postpartum were 53.8% and 7.8%, respectively. This difference reached statistical significance (p<0.001). There were 53.5% of stress UI, 20% of urge incontinence, and 7.8% of mixed type UI during late third trimester, whereas only stress UI was found in three months postpartum period. The only risk factor for late antenatal and early postpartum UI was high pre-pregnancy BMI (OR 2.3; 95% CI 1.38-3.85, p<0.001 and OR 3.3; 95% CI 1.8-6.0, p<0.001, respectively).

Conclusion: The prevalence of UI was quite high during the late third trimester (53.8%) and decreased significantly three months postpartum (7.8%). Pre-pregnancy BMI is the only risk factor for developing UI in late antenatal and early postpartum period. This may help obstetricians for prediction and prevention of UI during pregnancy and postpartum in high-risk group.

Keywords: Prevalence, Urinary Incontinence, Third trimester, Postpartum, Risk factor