Department of Obstetrics and Gynecology, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
Department of Legal Medicine, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
Forensic Sci Int. 2019 Sep;302:109888. doi: 10.1016/j.forsciint.2019.109888. Epub 2019 Jul 26.
Pregnant women often suffer from negative fetal outcomes, despite wearing a seatbelt correctly. When restrained vehicle passengers are involved in a frontal collision without suffering from any injuries, the forces they experience are particularly concentrated in the chest because of the seatbelt. We analyzed the biomechanics of chest injuries sustained by restrained pregnant drivers and possible effects of these injuries on the fetus.
The Maternal Anthropometric Measurement Apparatus dummy, version 2B, representing a pregnant woman at 30 weeks of gestation, was used. Sled tests were performed for recreating frontal impact situations with vector velocity changes at impact speeds of 13, 26, and 40km/h. Overall kinematics of the dummy were examined using high-speed video imaging. Quantitative dummy responses, such as time course of acceleration of the sled and chest, pressure of the belt, and deflection of the chest (right and left) during impact were also measured.
Although collision velocities were different, the distances of forward movement of the dummy were similar (121-129mm) owing to the safety devices. However, maximum deflection of the chest (35.4mm to the left and 15.7mm to the right) was obtained at a 26-km/h collision. Additionally, maximum deflection of 28.7mm to the left and 10.9mm to the right of the chest were obtained at 40km/h.
Because the uterus enlarges and the fundus reaches the lower part of the rib cage during late pregnancy, we consider that the reason for negative fetal outcomes is partly owing to chest compression and subsequent applied forces on the uterus, even in minor to moderate frontal collisions. This knowledge may be useful for forensic scientists who determine the causes and mechanisms of a fetal death or the offenders' responsibilities for both maternal and fetal outcomes when the mother is involved in a frontal vehicle collision.
尽管孕妇正确系好了安全带，她们仍经常遭遇负面的胎儿结局。当约束在车内的乘客在没有受伤的情况下遭遇正面碰撞时，由于安全带的存在，他们所承受的力特别集中在胸部。我们分析了约束孕妇驾驶员胸部受伤的生物力学机制以及这些损伤对胎儿可能产生的影响。
使用 Maternal Anthropometric Measurement Apparatus （MAMA） 假人 2B 版本，代表妊娠 30 周的孕妇。进行了滑橇测试，以模拟冲击速度为 13、26 和 40km/h 的正面碰撞情况。使用高速视频成像检查假人的整体运动学。还测量了假人在碰撞过程中的加速度、胸部压力、安全带压力和胸部（左右）挠度等定量响应的时间历程。
尽管碰撞速度不同，但由于安全装置的作用，假人的向前移动距离相似（121-129mm）。然而，在 26km/h 的碰撞中，胸部的最大挠度为 35.4mm （左侧）和 15.7mm （右侧）。此外，在 40km/h 的碰撞中，胸部的最大挠度为左侧 28.7mm 和右侧 10.9mm。
由于子宫在妊娠晚期增大且宫底到达肋骨下部分，我们认为，即使在轻微到中度的正面碰撞中，导致胎儿不良结局的部分原因是胸部受压，随后对子宫施加了作用力。这些知识可能对法医科学家有用，他们在母亲遭遇正面车辆碰撞时，确定胎儿死亡的原因和机制，以及母亲和胎儿结局的罪犯责任。
