While the literature is clear that childbirth is a risk factor for pelvic floor dysfunction, how does a first childbirth affect the pelvic floor muscles? Does a vaginal delivery, instrumented delivery, or cesarean delivery affect the muscles differently? These questions were addressed in a prospective, repeated measures study involving 36 women. Outcomes included pelvic muscle function via vaginal squeeze pressure and questionnaires, prior to and following childbirth. The women were first evaluated between 20-26 weeks gestation and again between 6-12 weeks postpartum. All participants were primiparas, meaning that they had not given birth previously, and were found to have a significant decrease in strength and endurance after their first childbirth.
Pelvic floor muscle strength and endurance testing included maximum voluntary contraction (3 repetitions for up to 5 seconds) , sustained contraction, and repeated contractions at least 15 times. Ability to correctly contract the pelvic muscles was assessed via vaginal digital testing (with one examining finger) and perineal observation. A Myomed device was utilized with a vaginal sensor to more accurately measure strength. At the time of postpartum measurement, 33 of the 36 women were breastfeeding, the instrumented deliveries were completed with vacuum extraction, and all episiotomies were performed as right mediolateral procedures. Although the women in the study were asked if they completed pelvic muscle exercises- they were not instructed in any specific exercises.