Thanks. I get it, I really do, but if it's soooo much safer for kids to remain RF until 2 yrs then why is the law still 1 yr and 20 pounds? It's very confusing. And if I return my combination seat and get a convertible, does this mean I will be having to get a separate booster down the road?
Well, there's two things to consider here. How the government machine works, and how physics work.
Here's the physics side of the equation:
Everybody knows that there are gaps in an infant's skull so that the brain can grow. What most parents don't realize is that the whole spinal column is set up the same way. Every vertebrae in their neck and back has three gaps covered with connective tissue so that they do not form a complete circle. This allows the pieces of bone to get wider as the spinal cord gets bigger around.
A car seat that is rear facing will move with a child in a crash and his head and neck are supported by the car seat shell. Basically, the car seat acts as a back board/stretcher.
When a child is forward facing and his head whips forward and side to side in a crash, this connective tissue can let the pieces of bone in the neck stretch up to two inches. The spinal cord itself can only stretch about a quarter of an inch before it snaps.
These gaps in the bone BEGIN to close up around age one, and complete the process at around age six. A one year old is safER ffing than a newborn, because the head is not as large in proportion to his body, but the bone structure itself is no more mature, so the risk to the spine is still really significant.
And here is where the law comes in:
Years ago the 1 year recommendation for ffing was decided on because, at the time, that was the size of child the car seats on the market could reasonably accommodate. We had no choice but to take the risk of ffing before the neck had developed, and there would have been no value in writing a law that was impossible to buy the equipment to follow.
We have car seats today that can keep a child rfing for much longer and protect their spines longer. What we don't have is the money to go about changing laws that typically encounter great opposition in the first place (It took 5 years to pass the booster seat law here in CA because a certain individual in the state capital opposes seat belt laws for all passengers). With the economy the way it is right now, our representitives have bigger priories than changing a law that benefits people that are 17 years away from being able to vote.