Effects of Age and Parity on Pelvic Floor Dysfunction and Recovery in the Early Postpartum Period: A Retrospective Cohort Study.

Aims/Background Pregnancy and childbirth can significantly alter pelvic floor structure and function, particularly during the postpartum period, often resulting in dysfunction. Although maternal age and the number of vaginal deliveries have been reported as risk factors for pelvic floor dysfunction, studies on how these factors interact to impact pelvic floor dysfunction and recovery in the postpartum period are limited. Therefore, this study explored the integrated effects of age groups and the number of vaginal deliveries on pelvic floor electromyography and structural indicators among postpartum women. Methods This retrospective cohort study collected data of 245 postpartum women 42-60 days after delivery from the clinic's records of the Jiading District Central Hospital Affiliated Shanghai University of Medicine and Health Sciences between January 2020 and December 2022. Of these patients, 108 were multiparous and 137 were primiparous. Based on age, participants were divided into two groups: ≤30 (n = 102) and >30 (n = 143) years groups. Pelvic floor recovery was compared across these subgroups using ultrasound and electromyography (EMG). Results Findings revealed age-related disparities in electromyography findings of slow-twitch pelvic floor muscles. Postpartum women aged ≤30 years exhibited higher endurance contraction variability of slow-twitch muscles (p = 0.049). Pelvic floor ultrasound showed that women aged >30 years had greater anorectal angles (p = 0.024) and levator hiatus areas (p = 0.034) after the Valsalva maneuver. Multiparous women exhibited increased variability in slow-twitch muscle contractions (p = 0.026) and prolonged relaxation time (p = 0.031). Primiparous women showed higher post-resting average values (p = 0.009). Pelvic floor ultrasound indicated greater bladder neck mobility (p < 0.001), levator hiatus area (p = 0.013), and urinary incontinence prevalence (p = 0.026) in multiparous women. When cross-grouped, multiparas ≤30 years exhibited higher pre-resting EMG values (p = 0.035). Additionally, tonic contraction variability (p = 0.014), tonic contraction relaxation time (p = 0.025), and post-resting mean values (p = 0.003) showed significant differences, particularly in women over 30. In contrast, multiparas demonstrated both increased bladder neck mobility (p = 0.004) and significant differences in the anorectal angle (p < 0.001) and levator hiatus area (p = 0.038) compared to other groups. Conclusion Reproductive-aged women over 30 years with multiple deliveries exhibit compounded pelvic floor dysfunction, particularly in slow-twitch muscle coordination and structural support parameters (anorectal angle and levator hiatus area), informing targeted rehabilitation strategies to optimize rapid recovery.