Biomechanics of Birth – The Fallacy of Gentle Birth: Physician Exerted Pressures in Vaginal and Cesarean Delivery

Vaginal delivery may be complicated by either disproportion with the maternal pelvis or fetal malpresentation. Shoulder dystocia with brachial plexus injury is a frequent subject of medical malpractice complaints based on the assumption injury equals excess physician force despite the fact the normal range of force is unknown. Further, cesarean delivery has become common in part based on the assumption it is gentler than vaginal delivery. Unfortunately, there have been few attempts to quantify the physician-exerted forces required for vaginal delivery, and none for cesarean delivery. This study initiates our investigation into physician hand exerted pressures required for human birth. Our long-term goal is to use calibrated pressure sensors and motion analysis of the physician hands to calculate forces exerted on the fetus at birth. In the present study, pressure sensors were attached to gloves to record physician-exerted pressures during six vaginal (one with shoulder dystocia) and six cesarean deliveries (one of a breech fetus). The subject mean and peak values (over time) of the average sensor pressure were significantly greater for cesarean than vaginal deliveries. This study provides the first pressure data for cesarean delivery of vertex and breech fetuses and reveals that the pressure exerted for cesarean delivery is greater than vaginal delivery. Though the peak pressure among vaginal deliveries was highest with shoulder dystocia, it was still less than the peak pressures required for cesarean delivery. In conclusion, these studies reveal the complexity of assessing the total forces of delivery (maternal, uterine and physician) and represent a first step toward accurate modeling of delivery biomechanics, the development of teaching tools to enhance safety, and a reduction in malpractice claims based on faulty assumptions.