Birth trauma: short and long term effects of forceps delivery compared with spontaneous delivery on various pelvic floor parameters

Objective To compare the effects of forceps delivery and spontaneous delivery on pelvic floor functions in nulliparous women. Design A longitudinal prospective study with investigations during the first pregnancy, 10 weeks and 10 months after delivery. Setting Antenatal clinic in a teaching hospital. Population One hundred and seven patients aged 28.4 years, divided into those with forceps (n= 25) or spontaneous (n= 82) delivery. Methods Investigations with a questionnaire, clinical examination, assessment of bladder neck behaviour, urethral sphincter function, intra‐vaginal/intra‐anal pressures during pelvic floor contractions. Results The incidence of stress urinary incontinence was similar in both groups at 9 weeks (32%vs 21%, P= 0.3) and 10 months (20%vs 15%, P= 0.6) after delivery, as was the incidence of faecal incontinence (9 weeks: 8%vs 4%, P= 0.9; 10 months: 4%vs 5%, P= 1) and the decreased sexual response at 10 months (12%vs 18%, P= 0.6). Bladder neck behaviour, urethral sphincter function and intra‐vaginal and intra‐anal pressures were also similar in the two groups. However, 10 months after delivery, the incidence of a weak pelvic floor (20%vs 6%, P= 0.05) and the decrease in intra‐anal pressure between the pre‐ and post‐delivery values (−17±28 cm H2O vs 3±31 cm H2O, P= 0.04) were significantly greater in the forceps‐delivered women. Conclusions Forceps delivery is not responsible for a higher incidence of pelvic floor complaints or greater changes in bladder neck behaviour or urethral sphincter functions. However, patients with forceps delivery have a significantly greater decrease in intra‐anal pressure and a greater incidence of a weak pelvic floor.