Symptomatic pelvic organ prolapse in middle-aged women - a national matched cohort study on the influence of childbirth

Abstract BACKGROUND The relative impact of age, pregnancy and vaginal delivery on symptomatic pelvic organ prolapse is still an unresolved issue that involves the controversial question about the protective effect of cesarean section. OBJECTIVES The purpose of this study was to compare the age-related prevalence of symptomatic genital prolapse in nulliparous, vaginal and cesarean delivered women aged 40 to 64 years. STUDY DESIGN This Swedish, nationwide matched cohort study involved 14,335 women. Three restricted, randomly selected source cohorts of women (nulliparous women unexposed to childbirth (n = 9136), one-para cesarean delivered women, exposed to one pregnancy (n = 1412), and one-para women exposed to one pregnancy followed by vaginal delivery (n = 3787) were retrieved from The Swedish Medical Birth Register and Statistics Sweden and surveyed in 2008 and 2014. The surveys used a postal and internet-based questionnaire containing validated questions for pelvic floor disorders. Symptomatic prolapse was defined by the question “Do you have a sensation of tissue protrusion (a vaginal bulge) from your vagina?”. In this study the symptom frequencies “Sometimes and Often” were defined as a positive response. Parous women were all assessed 20 years postnatally. One-to-one matching with an age interval for pairing of three years and three units of body mass index (kg/m2) was used in women aged 40 to 64 years. The procedure succeeded in 2,635 out of 2,640 women (99.8%), resulting in an adequate distribution of age and body mass index (kg/m2) between matched groups. For comparison between groups Fisher’s exact test was used for categorical variables and the Mann–Whitney U test for continuous variables. Trend between matched groups was analysed with Mantel-Haenszel statistics. Estimated, age-related values of symptomatic prolapse were obtained by logistic regression analysis. RESULTS In nulliparous and cesarean delivered women the prevalence of symptomatic prolapse was relatively similar and below 5% across ages 40 to 64 years. In contrast, in women after vaginal delivery, there was an accelerating increase in the prevalence of symptomatic genital prolapse up to 65 years of age. Estimated probability from the regression model increased fourfold from 3.8% at 40 years to 13.4% at 64 years of age. The observed induction period associated with one vaginal delivery seemed to be at least 20 years among women giving birth in their early twenties. At age 64 the estimated probability of symptomatic prolapse was twelve times higher after vaginal delivery compared to cesarean section [13.4 % (95% CI 9.4-18.9) versus 1.1 % (95% CI 0.4-2.5 ), P CONCLUSION In this national matched cohort study the interaction between vaginal delivery and aging was the most important factor for the occurrence of symptomatic prolapse. Since the effect of aging can only be modified to a small extent, preventive strategies for genital prolapse should focus on how to avoid the adverse events related to a vaginal delivery.