Correct Use of a Conventional Lap-and-Shoulder Seatbelt Is Safest for Pregnant Rear-Seat Passengers: Proposal for Additional Safety Measures

Abstract

The objectives of this study were to assess the safety of various methods of seatbelt use and propose safety improvements to the lap-and-shoulder seatbelt for pregnant rear-seat passengers. The Maternal Anthropometric Measurement Apparatus dummy, version 2B, was used. Sled tests were performed to simulate frontal impact at a speed of 48 km/h in the right rear seat. Kinematics of the dummy were examined using high-speed video imaging, and time courses of the seatbelt loads and displacement and acceleration of the chest and pelvis were measured during impact. The kinematic parameters were compared under the following conditions: conventional lap-and-shoulder seatbelt used correctly, lap belt crossed over left and right femurs, and lap belt attached to both thighs using an extra restraint device. Then, by applying pretensioner and/or force limiter systems, the safest condition was investigated. Correct conventional seatbelt use was the most effective restraint method. When both pretensioner and force limiter were applied, the kinematic parameters were smallest, and the best restraint was achieved. The safety of rear-seat travel can be improved by using both pretensioner and force limiter systems, which would reduce the risk of chest and abdominal injuries to pregnant passengers and prevent negative fetal outcomes.