The influence of neonatal birth weight on postpartum pelvic floor function in primiparas.

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.