What is to blame for postnatal pelvic floor dysfunction in primiparous women—Pre-pregnancy or intrapartum risk factors?

The aetiology of pelvic floor dysfunction (PFD) is still poorly understood. However childbearing is recognized as a major risk factor.To elucidate the natural history of PFD by investigating the impact of the mode of delivery on postnatal pelvic floor dysfunction in primiparas, when PFD existing before the first pregnancy is taken into consideration.4P-study (Prevalence and Predictors of Pelvic floor dysfunction in Primips) is a prospective cohort study, nested within the Screening for Pregnancy Endpoints (SCOPE) study set in a tertiary referral teaching hospital with 9000 deliveries annually. Established and proposed risk factors for urinary, fecal, prolapse and sexual dysfunction and the severity of symptoms for each of these outcomes were assessed using the Australian Pelvic Floor Questionnaire in 1482 nulliparous women, who each completed the questionnaire in early pregnancy. Of these, 1060 (72%) repeated the questionnaire 12 months postpartum.Outcomes were analyzed using multivariate ordinal logistic regression.Significant (p<0.05) risk factors for postpartum PFD were pre-pregnancy presence of similar symptoms Odds Ratio (OR) (5.0-30.0), smoking (OR 2.2-4.6), recurrent UTI (OR 2.2-17.3), high hip circumference (OR1.4-1.6), vigorous exercising (OR 3.1-17.9), induction of labor (OR 1.5-2.3), forceps delivery (OR 1.8-8.8), and 3rd degree perineal tear (OR 2.4-2.7). Cesarean section was associated with a lower risk of stress urinary incontinence (OR 0.3-0.5). Other common pre-pregnancy significant (p<0.05) risk factors for various PFD types prior to the first pregnancy were: diagnosed depression - (OR 1.6-2.1), high BMI (OR 3.1), strenuous exercising (OR 1.3-2.2), recurrent UTI (OR 1.5-2.5) and lower educational achievement (OR 1.5-1.6).Pre-pregnancy PFD was mainly associated with modifiable risk factors such as smoking and exercising. The main risk factor for postpartum PFD was the presence of similar symptoms prior to pregnancy, followed by anthropometric and intrapartum factors. Hip circumference seems to be a better predictor of PFD compared to BMI. When pre-pregnancy PFD was included in the analysis, Cesarean section was protective only for stress urinary incontinence, while delivery by forceps increased the risk of prolapse.