Pelvic floor dysfunction after intervention, compared with expectant management, in prolonged second stage of labour: A population-based questionnaire and cohort study

Objective: To investigate the effect of vacuum extraction (VE) or caesarean section (CS), compared with expectant management, on pelvic floor dysfunction (PFD) 1–2 years postpartum in primiparous women with a prolonged second stage of labour. Design: A population-based questionnaire and cohort study. Setting: Stockholm, Sweden. Population: A cohort of 1302 primiparous women with a second stage duration of ≥3 h, delivering from December 2017 to November 2018. Methods: The 1-year follow-up questionnaire from the Swedish National Perineal Laceration Register was distributed 12–24 months postpartum. Exposure was VE or CS at 3–4 h or 4–5 h, compared with expectant management. Main outcome measures: Pelvic floor dysfunction was defined as at least weekly symptoms of urinary incontinence, pelvic organ prolapse or a Wexner score of ≥4. The risk of PFD was calculated using Poisson regression with robust variance estimation, presented as crude and adjusted relative risks (RRs and aRRs) with 95% confidence intervals (95% CIs). The implication of obstetric anal sphincter injury (OASI) on pelvic floor disorders was investigated through mediation analysis. Results: In total, 35.1% of women reported PFD. Compared with expectant management, the risk of PFD was increased after VE at 3–4 h (aRR 1.33, 95% CI 1.06–1.65) and 4–5 h (aRR 1.34, 95% CI 1.05–1.70), but remained unchanged after CS. The increased risk after VE was not mediated by OASI. Conclusions: Pelvic floor dysfunction was common in primiparous women after a prolonged second stage, and the risk of PFD increased after VE but was unaffected by CS, compared with expectant management. If a spontaneous vaginal delivery eventually occurred, allowing an extended duration of labour did not increase the risk of PFD.