BEST CLINICAL PAPER: Pelvic Floor Symptoms 4 Years After Planned Labor Induction versus Expectant Management

Objective: Pelvic floor disorders (PFDs) are common and burdensome. There is perception amongst women that labor induction causes more painful or difficult labor, and that this may subsequently predispose women to pelvic floor damage. Data about the effect of induction of labor on PFDs are sparse and results are mixed. The aim of this follow-up study to a randomized trial is to determine whether labor induction increases the risks of urinary incontinence, anal incontinence, and symptomatic prolapse.

Methods: This is a follow-up study of the ARRIVE trial (A Randomized Trial of Induction Versus Expectant Management) conducted by the Maternal-Fetal Medicine Units Network in which low-risk nulliparas with a singleton fetus in the vertex presentation were randomized to elective induction of labor at 39 weeks 0 days to 39 weeks 4 days of gestation or expectant management in which induction occurred no earlier than 40 weeks 5 days. Participants were invited to complete pelvic floor symptom questions 4 years (IQR 3.5-5.3) after delivery, including the 3 Incontinence Questionnaire (3-IQ), Incontinence Severity Index (ISI), and questions about anal incontinence and prolapse from the Epidemiology of Prolapse and Incontinence Questionnaires (EPIQ), as well as questions about subsequent pregnancies and other demographics. Three primary outcomes included moderate to severe urinary incontinence (ISI score > 3), anal incontinence (loss of gas, liquid or solid stool > once/month), and sensation of vaginal bulge. We excluded women recently delivered or currently pregnant at follow-up. Adjusted analysis using log-binomial regression modeling included number of pregnancies (>20 weeks gestation), maternal age, body mass index (BMI) at index pregnancy, and subsequent modes of delivery.

Results: 766 of 1042 original participants responded (74%). After excluding 119 for current or recent pregnancy, 647 participants were included in the analysis. Follow-up duration since index delivery ranged from 2.5-6.4 years. The mean age for both groups was 25(SD=4) years and body mass index 31 kg/m2 (SD=6). Overall prevalence of moderate to severe UI, AI and POP were 21%, 14% and 8%. There were no significant differences in any primary outcome between women randomized to induction of labor versus expectant management (Figure), either on unadjusted or adjusted analyses. There were also no differences in secondary outcomes, including subtypes of urinary incontinence or flatal versus stool incontinence.

Conclusions: As the original multicenter ARRIVE trial concluded that labor induction at 39 weeks in low-risk nulliparas did not differ from expectant management in composite adverse perinatal outcome, but did result in a fewer cesarean deliveries, more women may choose induction. Our results from a single site did not demonstrate an increased risk with elective induction of urinary incontinence, anal incontinence, or symptomatic vaginal bulge, although for the least frequent outcome (prolapse) meaningful differences cannot be ruled out.