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Abstract

Motor vehicle collisions (MVCs) are the leading cause of trauma in pregnancy to both the carrying parent and the fetus. Pregnant individuals involved in a MVC have an increased risk of adverse fetal and pregnancy outcomes even when injuries to the pregnant individual are minor, but the difference in the absolute risk of minor injury between pregnant and non pregnant females is unknown. The mechanisms of MVC-related injury are identified using human surrogates. While these models have been adapted for use in pregnant occupant motor vehicle safety, the pregnant surrogates are based on manually measured seated anthropometry, which don’t consider changes in internal anatomy, and supine medical imaging, ignoring the effects of a seated posture on soft tissue distribution and the geometry of internal anatomical structures such as the uterus in a seated posture. This study aimed to further the field of motor vehicle safety for pregnant occupants by: (1) Comparing the relative risk of minor injury between age-matched pregnant and non-pregnant female vehicle occupants in the United States following a MVC, (2) Quantifying uterine geometry in a diverse subject pool of pregnant individuals between 24- and 36-weeks gestation in automotive seated, supine, and standing postures, and (3) Estimate abdominal loads and compression, and uterine strain in pregnant individuals with computational simulated crash severities between 15 and 50 km/h using subject-specific MRI scans. From (1), we found that pregnant individuals were significantly more likely to sustain minor injuries (OR: 2.46, CI: 1.85-3.26), specifically to the abdomen and extremities, than non-pregnant females. From (2), we found that the pregnant uterus had changes in its dimensions, uterine tilt, and maximum protrusion from both the pelvis and spine between gestational week groups and postures. From (3), the calculated force and compression on the pregnant abdomen from simulations increased significantly with body mass and abdominal adipose tissue depth. These findings highlight that pregnant occupants are at a higher risk of minor injury than non pregnant females in similar severity impacts and that changes in gestational age, posture, and body morphology significantly impact uterine geometry.