Association of the second birth mode of delivery and interval with maternal pelvic floor changes: a prospective cohort study.

BACKGROUND: This study aimed to explore the association of the second birth delivery mode and interval with maternal pelvic floor changes.

METHODS: This prospective cohort study included women who had a first delivery and were in weeks 36-41 of a subsequent pregnancy at Panzhihua Central Hospital between July 2017 and June 2018. The primary outcomes of the study were the hiatus area at 6 months postpartum and bladder neck (mm) at rest and during a maximum Valsalva maneuver.

RESULTS: There were 112 women with vaginal delivery and 182 with Cesarean section. The hiatus area and hiatus circumference decreased at all time points (all P < 0.001). The women with Cesarean section had a smaller hiatus area and circumference (P < 0.001 and P < 0.001). The hiatus diameters decreased with time in both groups (all P < 0.001) and were smaller after Cesarean section (both P < 0.001). The bladder neck at maximum Valsalva increased with time (all P < 0.001) without significant differences between the two groups. Finally, the proportion of patients with POP-Q stage 0/I increased with time in both groups (all P < 0.001), with the proportions being higher in the Cesarean group (P = 0.002). The birth interval was negatively correlated with the hiatus area (B=-0.17, 95%CI: -0.25, -0.08, P < 0.001) and positively correlated with the bladder neck at rest (B = 0.22, 95%CI: 0.08, 0.35, P = 0.001) and at maximum Valsalva (B = 0.85, 95%CI: 0.65, 1.05, P < 0.001).

CONCLUSIONS: In conclusion, the mode of delivery at the second birth could influence the hiatus area and circumference and bladder neck size. The birth interval was negatively correlated with the hiatus area and positively correlated with the bladder neck at rest and at maximum Valsalva.