Long-term effect of vaginal deliveries on anorectal function in normal perimenopausal women

PURPOSE: This study was undertaken to determine the long-term effects of vaginal deliveries on anorectal function in healthy perimenopausal women. METHODS: An observational study of 144 perimenopausal women living in the county of Aarhus, Denmark, aged 45 to 57 (mean, 50) years were randomly selected from the National Register. All women had delivered 0 to 6 (mean, 2) times 10 to 34 years before the investigation. Examinations describing pelvic floor function were measurements of perineal position at rest and descent during straining, anal mucosa electrosensitivity, maximum resting pressure and maximum squeeze pressure of the anal sphincters, and pudendal nerve terminal motor latency. All tests were performed by one of the authors (AMR) and without knowledge of parity. Data were analyzed using the multiple regression technique, and all associations between anorectal function and parity were corrected for age and hysterectomy status. RESULTS: Increasing parity correlated with a lowered perineal position at rest (correlation coefficient (r) = 0.26: P = 0.003), an increased descent during straining (r = 0.24; P = 0.006), an increased threshold of anal mucosa electrosensitivity (r = 0.21, P = 0.008), and an increased pudendal nerve terminal motor latency on both sides (r = 0.27; P = 0.002). No effect of parity on the maximum resting pressure (r = 0.06; P = 0.70) and maximum squeeze pressure (r = 0.06, P = 0.36) was found. The number of vaginal deliveries account for only a minor fraction of the total variability seen in the tests of pelvic floor function (between 1.6 and 5.7 percent), CONCLUSION: Repeated vaginal deliveries have a long-term adverse effect on anorectal physiology in a population of randomly selected healthy perimenopausal women.