A recent Quora query went like this: What is the safety effect of rear-facing car seats and forward-facing car seats/boosters?
My answer was pretty simple:
You’re describing three different things here. So it’s worth looking at each individually.
The infant seat, which faces rearward in the car, is equipped with two items that are the primary safety items on them: a 5-point harness and a seatback facing towards the most likely collision point. The 5-point harness not only secures baby in the seat, but it also spreads the load of an impact across the little one’s torso, which lowers the amount of stress on any given point of baby’s body. The rear-facing seat means that in a forward collision, which is the most likely collision point at speed, the G force of the sudden stop is absorbed by the baby’s back and ribs, again spreading the load of the impact. Specifically, this spread of forces backwards supports baby’s head and neck.
The forward-facing child safety seat, similar to that infant seat, also has a 5-point harness and secure anchor to the car’s seat so it won’t move on impact. Unlike the rear-facing seat, however, the forward-facing seat puts all of the forward impact forces onto the child’s body front (torso), but still spreads it with the 5-point harness. The larger child should be able to take this impact.
Finally, booster seats are nothing more than devices used to position a child so that the car’s built-in seatbelts are correctly positioned on the child’s body. They basically raise the child upwards so that the shoulder part of the belt goes over the child’s shoulder and across his/her chest. Without the booster, the seatbelt would likely be across the child’s chin or neck; neither of which is safe in an impact. At this point, a child is considered large and strong enough to take the same body forces as an adult in terms of G-force distribution.