Biomechanical Impact of Recurrent Childbirth on the Female Pelvic Floor.

Every year, millions of childbirths occur globally, yet the rate of maternal morbidity and mortality remains unacceptably high. This study investigates the biomechanical impact of multiple vaginal deliveries on pelvic floor dysfunction (PFD), a key contributor to maternal morbidity. While the effects of first childbirth on pelvic floor injuries have been widely studied, less is known about the impact of subsequent deliveries. Epidemiological data show that the risk of PFD increases with the number of births, making it crucial to understand how later deliveries exacerbate damage. Using a finite element model, this research simulates the biomechanical effects of first and second vaginal delivery. The model incorporates pelvic floor muscles and a fetal head, considering factors such as muscle recovery and fetal head size. Simulations were run for both first and second deliveries, with varying recovery rates of muscle damage and fetal head sizes (50th and 5th percentiles). Results indicate that muscle damage is most severe at the pubovisceral muscle's origin, which is consistent with previous studies. In second-birth simulations, more muscle damage was observed, particularly when no recovery occurred. Smaller fetal head sizes led to less muscle stretch and accumulated damage. The study supports existing literature linking subsequent childbirths to a higher risk of PFD and highlights the importance of muscle recovery in mitigating damage. It also provides valuable insights into the biomechanics of childbirth, offering a step forward in improving understanding of pelvic floor injuries.