Computational modeling of vacuum-assisted delivery: biomechanics of maternal soft tissues

Childbirth is a complex process influenced by physiological, mechanical, and hormonal factors. While natural vaginal delivery is the safest, it is not always feasible due to diverse circumstances. In such cases, assisted delivery techniques, such as vacuum-assisted delivery (VAD), may facilitate vaginal birth. However, this technique can be associated with a higher risk of maternal injuries, potentially resulting in long-term conditions such as pelvic organ prolapse or incontinence. This study investigates the biomechanical impact of VAD on maternal tissues, aiming to reduce these risks. A finite element model was developed to simulate VAD, incorporating maternal musculature, a deformable fetal head, and a vacuum cup. Twelve simulations were conducted, varying contraction durations, resting intervals, and the number of pulls required for fetal extraction. Results revealed that prolonged contraction durations, coupled with extended resting intervals, lead to a reduction in pelvic floor stress. Elevated stress levels were observed when fetal extraction involved two pulls, with an 8.43% decrease in maximum stress from two pulls to four. The peak stress recorded was 0.81 MPa during a 60-second contraction, followed by a 60-second rest period. These findings indicate that longer maneuvers may reduce trauma, as extended pulls allow muscles more time to relax and recover during both contraction and rest phases. Furthermore, an increased number of pulls extends the duration of the maneuver, facilitating fetal rotation and improved adjustment to the birth canal. This study offers crucial insights into the biomechanics of childbirth, providing clinicians with valuable information to enhance maternal outcomes and refine assisted delivery techniques.