Objective: Our goal was to develop a pregnancy insert for the Hybrid III (First Technology, Farmington, Mich.) crash dummy allowing evaluation of the effects of various restraint conditions on energy transmission to both the fetal and maternal compartments.
Study design: A pregnancy insert with an elasticized vinyl uterine shell, simulated silicon amniotic fluid, and a 28-week simulated fetus was fitted to a female crash dummy. The fetus was instrumented with accelerometers in the head and thorax and a transducer to measure force transmission through the uterus. Thirty-nine crash tests were run under six different restraint conditions at speeds ranging from 10 to 25 miles/hr. Fetal responses were compared for different restraint conditions.
Results: Increasing speed of the crash resulted in greater force transmission through the uterus. Placement of the lap belt over the uterus instead of under the uterus resulted in a threefold to fourfold increase in force transmission through the uterus at all speeds tested. Air bag deployment in the unbelted or out-of-position dummy (laying against air bag) appears to impart significant energy transmission to the fetus.
Conclusions: Energy transmission can be measured in terms of both abdominal force and acceleration within the fetal head and thorax. This new dummy demonstrates substantial transmission of energy, which is accentuated in some restraint conditions commonly used by pregnant women. The use of the 3-point restraint system appears to reduce the likelihood of injury in this model.