Pelvic floor mechanics during childbirth for athletic and non-athletic women

Abstract

There is preliminary evidence to suggest that female athletes who undergo sustained, high-impact training tend to experience a prolonged second stage of labour compared to non-athletes. It is postulated that such training can cause changes in muscle size and tone, which may contribute to birth complications. The aim of this study, therefore is to create a simplified model of the mechanics of the second stage of labour. In order to do this, we created two finite element descriptions of the geometry of the pelvic floor (13 components) from magnetic resonance images of one nulliparous athlete and one non-athlete. To model the second stage of labour, the fetal head was passed through the levator ani muscle over several displacement steps. The muscle was fixed at its attachment points to the bony pelvis. The mechanical interaction between the head and the passive muscle was modelled using finite deformation elasticity coupled with frictionless contact mechanics. The simulation indicated that the peak force required for the athlete was 30% more than that for the non-athlete, indicating that greater force during childbirth is required for athletic mothers. The maximum principal stretch ratio exceeded 2 for both the athlete and the non-athlete.