Stress and urgency urinary incontinence one year after a first birth—prevalence and risk factors. A prospective cohort study

Few prospective studies have examined the effect of pregnancy and childbirth on stress and urgency urinary incontinence separately. The aim of the present study was to assess the extent to which pregnancy, vaginal delivery, and vaginal delivery characteristics affect the risk of significant stress and urgency incontinence 1 year after delivery.We conducted a prospective cohort study of 670 nulliparous women from early pregnancy to 1 year partum. The women were recruited at maternity health care service in Region Örebro County, Sweden, between October 1, 2014 and October 1, 2017 and completed questionnaires in early and late pregnancy and at 8 weeks and 1 year postpartum. Primary outcome measures were significant stress and urgency incontinence at 1 year postpartum in women who reported being continent before pregnancy. Generalized linear models were used.Stress and urgency incontinence commencing before pregnancy were reported by 4% and 3% of women, respectively, in the first questionnaire in early pregnancy, and these women were excluded from subsequent analysis. Stress and urgency incontinence were reported by 21% and 8%, respectively, at 1 year postpartum, in women not reporting incontinence before pregnancy. Stress incontinence during pregnancy increased the risk of stress incontinence postpartum (risk ratio [RR] 2.48, 95% CI 1.86-3.3). Urgency incontinence during pregnancy increased the risk of urgency incontinence postpartum (RR 4.07, 95% CI 2.1-7.89). Vaginal delivery increased the risk of stress incontinence postpartum (adjusted RR 2.63, 95% CI 1.39-5.01) but not of urgency incontinence. This effect of vaginal delivery on stress incontinence was similar irrespective of incontinence status during pregnancy. The population-attributable fraction of stress incontinence associated with vaginal delivery was 0.58 (95% CI 0.23-0.77).This study shows essentially different risk factors for stress and urgency incontinence, supporting stress incontinence as being the subtype mostly associated with pregnancy and childbirth, and urgency incontinence as being more stable over time. At a population level, vaginal delivery was the major risk factor for stress incontinence, followed by reporting stress incontinence during pregnancy.