Abstract
This study aims to investigate the effect of birth weight on the incidence of pelvic floor dysfunction (PFD) in primiparas at 42 days and 1-year postpartum, using pelvic floor ultrasound and surface electromyography (sEMG). A retrospective analysis was conducted on 200 primiparas women who had a full-term vaginal delivery. All participants underwent pelvic floor evaluation at 6 to 8 weeks postpartum, with a follow-up at 1 year. The primiparas were categorized into 2 groups based on infant birth weight: a study group (n = 100, 3500 g ≤ birth weight <4000 g) and a control group (n = 100, 2500 g ≤ birth weight <3500 g). Significant differences were observed in prenatal body mass index, duration of the second stage of labor, incidence of gestational diabetes, perineal laceration, and episiotomy between the 2 groups (P <.05). At 42 days postpartum, the study group had significantly higher incidence rates of stress urinary incontinence, bladder prolapse, and uterine prolapse compared to the control group (P <.05). However, at 1-year postpartum, only the differences in the incidence of bladder prolapse and stress urinary incontinence remained statistically significant (P <.05). The sEMG assessment revealed significant differences in all 5 measured characteristics between the 2 groups at both 42 days and 1-year postpartum (P <.05). Ultrasound findings among PFD primiparas showed that, at 42 days postpartum, the study group had smaller bladder neck-symphaseal distance in the resting state and maximum Valsalva state (R-BSD and V-BSD), and greater bladder neck descent (BND), urethral rotation angle, and 1evator hiatus area in maximum Valsalva state (V-LHA) than the control group (P <.05). At 1 year, differences in V-BSD, BND, urethral rotation angle, and V-LHA remained significant. Among primiparas without PFD, significant differences were only found in V-BSD, BND, and V-LHA at both time points (P <.05). Higher birth weight is associated with impaired postpartum pelvic floor function and may be a significant risk factor for PFD.