Motor vehicle accidents are the largest single cause of accidental death and the leading cause of traumatic injuries for the pregnant occupant and her fetus. Computational pregnant occupant modelling has a role to play in the investigation of the risk of fetal injuries and mortality in crash test simulations. Effective investigation depends on realistic representation of pregnant occupant and her fetus in a virtual environment. However, known pregnant occupant models normally do not include a fetus in the uterus. ‘Expecting’, the first computational model of a pregnant occupant with a fetus, is used in the current research. The model has a detailed multi-body representation of the fetus as well as a finite element uterus and placenta.

In this paper, the effect of including the fetus in the uterus of the pregnant occupant model is investigated using ‘Expecting’ in crash test simulations. Previously, drop test simulations with and without a fetus showed that, the presence of fetus in the uterus suggests higher risks to the fetus. Using the pregnant occupant model, ‘Expecting’, with and without a fetus, provides more realistic simulations to explore the role of including a fetus in the uterus. Five frontal impact speeds, 15, 20, 25 30 and 35 kph with varying levels of restraint system including ‘seatbelt and airbag’ (ie fully restrained), ‘seatbelt only’, ‘airbag only’ and ‘no restraint’ are used in the simulations. Maximum strains developed in the uteroplacental interface with and without a fetus are compared. The effect of including a fetus in the pregnant occupant model is discussed.