Reducing pelvic floor injury by induction of labor

We hypothesized that elective induction of labor (eIOL) at 39 weeks is protective of levator ani muscle injury (LAMI) and is associated with decreased pelvic symptoms at 6 weeks postpartum compared to expectant management of labor.

Prospective cohort pilot study of uncomplicated, primiparous women with a singleton, vertex gestation enrolled immediately post-vaginal delivery (VD). Subjects were dichotomized into two groups based on labor management: eIOL without complication defined by the ARRIVE trial versus spontaneous VD between 39 weeks^0/7 and 42 weeks^5/7 or no indication for IOL prior to 40 weeks^5/7. The primary outcome was LAMI at 6 weeks postpartum as evidenced by any of the following ultrasound measures: (1) increased levator hiatal area (LHA) > 2500 mm², (2) increased elasticity index (EI, > 75th quartile) or (3) levator enthesis avulsion.

Analysis represents 45/102 consented women from July 2019-October 2020 (eIOL n = 22 and spontaneous VD, n = 23). Neither maternal, clinical, sociodemographic characteristics nor pelvic symptoms differed between groups. Fewer women had LAMI as defined by the primary outcome with eIOL (n = 5, 23.8%) compared to spontaneous VD (n = 15, 65.2%), p = 0.008. Levator enthesis was more deformable (increased EI) with spontaneous VD as compared to the eIOL [10.66 (8.99) vs. 5.68 (2.93), p = 0.046]. On univariate logistic regression women undergoing spontaneous VD had unadjusted OR of 6.0 (1.6-22.5, p = 0.008) of sustaining LAMI compared to those undergoing eIOL.

Composite measures of LAMI though not pelvic floor symptoms were markedly increased in women undergoing spontaneous VD compared to those undergoing eIOL at 39 weeks.