A recent article in Pediatrics, the Official Journal of the American Academy of Pediatrics, (excerpt) highlights the importance of extended rear-facing in carseats. The current MINIMUM requirement for turning a child forward-facing is 1 year AND 20 pounds. However, new studies have shown that this is inadequate, and the new MINIMUM should be 2 years AND 30 pounds. However despite the increased safety, few parents are following the new suggestions. A 2007 study done statewide in Indiana showed that while 85 percent of infants under age one are riding rear-facing in car seats, only seven percent of children between 1 and 2 are riding rear-facing. Here are some highlights from the print article, that show why "extended" rear-facing is so important.
"A recent analysis of the protection provided in rear-facing compared with forward-facing car safety seats has revealed that children under the age of 2 years are 75% less likely to die or sustain serious injury when they are in a rear-facing seat."
"The odds of severe injury for forward-facing infants under 12 months of age were 1.79times higher than for rear-facing infants; for children 12 to 23 months old, the odds were 5.32 times higher." (I think the under 1 information may be skewed because most people know the 1&20 rule and do not forward face their child before age 1 so there is less data to analyze. And this data only looked at children that were seriously injured, not killed and a child under 1 forward-facing in a serious crash is more likely to be killed than seriously injured.)
"Another barrier to implementation of this best-practice recommendation is the common myth that if a child's feet or legs reach the back of the vehicle seat, he or she is at an increased risk for a lower-extremity injury. Current data do not substantiate this myth. [...] In addition...these injuries, as well as injuries to the head and spine, have been described in forward-facing children in child-restraint systems."
Going along with the previous point, many people feel the child will be uncomfortable once their legs touch. LP is a very tall 2 year old, always in the 90th percentile for height, and is very comfortably still rear-facing. Children's legs are very flexible and they don't mind having them curled up in the seat or stretched out on the seat back. In fact, it is often more comfortable than having their legs hanging down without being able to rest anywhere.
Unfortunately the studies have only been done using data on children up to age 2, so they do not indicate what the safety increases are for children over 2. However it is well known that even adults are safer rear-facing in crashes, so it is safe to assume that a 2 or 3 year old who is under the height and weight limit for their seat would still be safer rear-facing.
OK, that's my public service announcement for now. I'll save extended harnessing for another day!