Rear facing is a much safer position because it distributes the crash forces across the entire body and protects the head and spine.
Once kids are turned forward facing the crash forces are much more concentrated increasing the likelihood of injuries occurring
Car seats now go to much high weight and height limits making it easier to keep kids rear-facing even up until the age of 3-4 years old.
Many may think that sounds a little crazy, and would argue that their legs will become cramped and uncomfortable.
Kids will fold their legs or stretch them up the back of the seat. Leg injuries do not increase with rear-facing use.
Keeping their head and spine protected is much better for the child and they will find ways to be comfortable.
Labels on car seats and owner manuals will show the weight and height limits of the car seats. If you choose to use an infant carrier when the child is first born, it is recommended to then switch to a convertible car seat that has a higher weight and height limit so rear facing can be extended.