The effect of placenta location on the safety of pregnant driver and her fetus

Placental abruption accounts for more than half of fetal mortality in automobile collisions. In most of the pregnancies, placenta is located at the fundus position of the uterus. However, in real life, placenta can also be found at different locations in the uterus. The goal of this study is to investigate whether the location of the placenta in the uterus of pregnant driver has a role on the risk of placental abruption in motor vehicle accidents. In addition to the most common fundus position, four other placental locations, namely anterior, posterior, lateral left and lateral right, are considered within the computational pregnant driver model ‘Expecting’, and used in collision simulations with impact severities from 15 to 30 kph with 5-kph increments. Scenarios also include four cases where the pregnant driver is fully restrained with three-point seatbelt and airbag, three-point seatbelt only, airbag only and no restraint at all. The maximum strains developed in the utero-placental interface of the model in this set of 64 simulations together with the fundus-location simulations are determined and compared in order to investigate the effect of placental location on the placental abruption prediction. Placenta located at anterior position is found to be at higher risk than other placental positions considered in this investigation. The results demonstrate that being fully restrained is the safest option and the three-point seatbelt is the most effective restraint system whilst the airbag makes a small contribution to the protection of pregnant driver and her fetus

Hybrid foetus with an FE head for a pregnant occupant model for vehicle safety investigations

‘Expecting’, a computational pregnant occupant model, developed to simulate the dynamic response to crash impacts, possesses anthropometric properties of a fifth percentile female at around the 38th week of pregnancy. The model is complete with a finite element uterus and a multi-body foetus which is a novel feature in models of this kind. In this paper, the effect of incorporating a foetus with a finite element head into ‘Expecting’ is investigated. The finite element head was developed using detailed anatomic geometry and projected material properties. Then it was integrated with the ‘Expecting’ model and validated using the lap belt loading and the rigid bar impact tests. The model is then used to simulate frontal impacts at a range of crash severities with seatbelt and airbag, seatbelt only, airbag only as well as no restraint cases to investigate the risk of placental abruption and compare it with the model featuring the original multi-body foetus. The maximum strains developed in the utero-placental interface are used as the main criteria for foetus safety. The results show comparable strain levels to those from the multi-body foetus. It is, therefore, recommended to use the multi-body foetus in simulations as the computation time is more favourable

The effect of including a fetus in the uterus model on the risk of fetus mortality through drop test and frontal crash simulations

© 2016 Informa UK Limited, trading as Taylor & Francis Group Computational modelling is an effective way of estimating the risk of injuries and fatalities in road traffic accidents. Computational pregnant occupant modelling has an additional important role in the investigation of the risk of fetus mortality in crash test simulations. In this paper, the effect of including the fetus in the uterus of the pregnant occupant model is investigated. First, isolated drop test simulations with the uterus of the computational pregnant occupant model, ‘Expecting’, with and without a fetus are used to show the effect of the presence of fetus in the uterus model. Then ‘Expecting’ with and without the fetus is used with varying levels of restraint system use, such as fully restrained, ‘seatbelt only’, ‘airbag only’ and ‘no restraint’, in frontal crash simulations, representing five levels of impacts. Maximum strains developed in the uteroplacental interface with and without a fetus are compared in every case. Both simulations predict higher risks of placental abruption when the fetus is included in the model. Simulations with and without a fetus model show that inclusion of a 38-week fetus model causes higher strains in the placental region of uterus