Analysis of pregnant occupant crash exposure and the potential effectiveness of four-point seatbelts in far side crashes.

The purpose of this paper is to present the crash exposure patterns of pregnant occupants and to evaluate the effectiveness of restraint systems, including four-point seatbelts, in far side crashes. The NASS CDS database revealed that 53.0 % of pregnant occupants are exposed to frontal crashes while 13.5 % are exposed to far side impacts. Given that far side crashes were the second leading crash mode after frontal impacts, a previously validated MADYMO computer model of a 30 week pregnant occupant was utilized to investigate pregnant occupant biomechanics in far side crashes. Three impact speeds (5, 15, and 25 mph) were simulated with four restraint conditions: unbelted, lap-belt only, three-point belt, and a four-point belt. Direct abdominal contact from the shoulder strap of the three-point or four-point belt caused uterine-placental strain in contrast to the inertial loading induced strain in the lap-belt and unbelted cases. Overall, the three-point and four-point belt systems provide superior restraint effectiveness for the pregnant occupant compared to the lap-belt and no restraint cases. The four-point resulted in slightly better performance than the three-point belt by reducing the fetal injury risk and occupant excursion.