Biomechanical modeling of pregnant occupants in far-side vehicle crashes.

Automobile crashes are the largest single cause of death for pregnant women and the leading cause of traumatic fetal injury mortality in the United States. The purpose of this paper is to evaluate the risk of fetal injury in pregnant occupants exposed to far-side vehicle crashes. A test matrix of nine computer simulations was performed using a computational model of a 30-week pregnant occupant. Three separate far-side impact severities were modeled including velocity changes of 5 mph, 15 mph, and 25 mph over the same 100 ms period. Three restraint conditions were modeled including no restraint, lap-belt only, and the three-point belt. All simulations at 5 mph resulted in very low risk of maternal or fetal injury. The simulations at 15 mph and 25 mph demonstrated the protective benefit of the three-point belt as both the lap-belt and no restraint tests resulted in the mother's head contacting the opposite door resulting in severe head injuries with HIC values above 2000. All simulations at 15 mph and 25 mph indicate possible fetal injury risk regardless of restraint condition as the peak strain values at the utero-placental interface were between 27.1% and 44.9% which equate to fetal injury risks between 36.9% and 61.0%. Direct abdominal contact from the shoulder strap of the three-point belt caused this strain in contrast to the inertial loading induced strain in the lap-belt and unbelted cases. Overall, the console was not a potential fetal injury mechanism in these simulations as the occupant either passed over it in the unrestrained simulations or rotated above it for the lap-belt and three-point belt tests. The results of this study are consistent with previous studies that show the three-point belt is the best and most important safety device for protecting pregnant occupants.