The Effect of Pregnant Occupant Position and Belt Placement on the Risk of Fetal Injury 2004-01-0324

The goal of this project was to evaluate the effect of occupant seating and seatbelt placement on the risk of adverse fetal outcome from a motor vehicle crash. Unrestrained, 3-pt belt, and 3-pt belt plus airbag tests were simulated with the Virginia Tech pregnant occupant computational model in both a driver-side and passenger-side vehicle interior in frontal impacts at 35 kph. The pregnant occupant model is a small female human body model modified to include a finite element uterine model. The model was previously created and validated with abdominal force-deflection responses. Peak uterine strain was reduced by 30% to 50% in passenger-side simulations vs. driver-side simulations. However, in the unrestrained, passenger-side simulation, the pregnant occupant sustained a HIC score of 2820, suggesting immediate maternal death and a high likelihood of fetal death. Additional simulations were run in which the vertical position of the lap-belt was varied through three heights. It was found that the vertical position of the lap-belt can increase the risk of adverse fetal outcome by a factor of three. The worse case lap-belt height corresponds to the belt being placed directly over the placenta. This case produced a peak uterine strain of 97%, well above the reputed tissue limit of 60%. It is recommended that, when practical, the pregnant woman ride in the passenger seat with a 3-pt belt. The seat should be positioned as far rearward as possible and the lap-belt should be worn as low as possible