Rear Facing Car Seats - What You Need to Know
Moms View Message Board: Parenting Discussion: Archive January-June 2005:
Rear Facing Car Seats - What You Need to Know
The bare minimum requirements for turning a baby forward facing are 12 mos. AND 20 lbs.. Safety Experts and the AAP now recommend babies stay rear facing as long as possible, until they reach the rear facing limits of their convertible car seat. The neck and spine are best protected during a crash when rear facing. Most convertibles now rear face up to 30 lbs., some up to 33-35. Height wise, there needs to be at least 1" of hard plastic seat shell above the child's head. As far as the legs, there have been no documented cases of broken legs from touching the vehicle seat back. Regardless, broken legs are MUCH easier to fix than a broken spine. More info here:
Rear-facing - Unmatched Safety
Below is an article by Kathleen Weber, the Director of the Child Passenger Protection Research Program at the University of Michigan Medical School
Rear-Facing Car Seats: What You Need To Know
Common Misunderstanding
There are many misunderstandings and misconceptions about the crash environment that lead even the best-intentioned parent or pediatrician to believe a child is "safe" facing forward when s/he is still very young. These come from obsolete ideas and advice that may still appear in older pamphlets and pediatric literature but that have been updated in recent years.
The most prevalent misunderstanding is the idea that muscle strength and control have anything to do with whether it is reasonable to face a child forward and subject his/her neck to the extreme forces pulling the head away from the body in a frontal crash.
Crash Dynamics
This will be a somewhat technical explanation, but it is an important concept to understand. When a car hits something else at, say, 25 miles per hour to 30mph, it will come to a stop at a deceleration rate of about 20 or 25G. But, due to the time lag between when the vehicle stops and the occupants eventually do, the head of a forward-facing adult or child may experience as much as 60 or 70G.
Physiological Impact
Even strong neck muscles of military volunteers cannot make a difference in such an environment. Rather it is the rigidity of the bones in the neck, in combination with the connecting ligaments, that determines whether the spine will hold together and the spinal cord will remain intact within the confines of the vertebral column.
This works for adults, but very young children have immature and incompletely ossified bones that are soft and will deform and/or separate under tension, leaving the spinal cord as the last link between the head and the torso. Have you ever pulled an electric cord from the socket by the cord instead of the plug and broken the wires? Same problem.
This scenario is based on actual physiological measures. According to Huelke et. al. (1), "In autopsy specimens the elastic infantile vertebral bodies and ligaments allow for column elongation of up to two inches, but the spinal cord ruptures if stretched more than 1/4 inch." Real accident experience has also shown that a young child's skull can be literally ripped from its spine by the force of a crash. Yes, the body is being held in place, but the head is not. Is it a statistically rare event? Yes. If it's my child, does it matter that it's rare?
Facing Directions
When a child is facing rearward, the head is cradled and moves in unison with the body, so that there is little or no relative motion that might pull on the connecting neck.
Another aspect of the facing-direction issue that is often overlooked is the additional benefit a child gains in a side impact. Crash testing and field experience have both shown that the head of a child facing rearward is captured by the child restraint shell in side and frontal-oblique crashes, while that of a forward-facing child is thrown forward, around, and often outside the confines of the side wings. This can make the difference between a serious or fatal head injury and not.
Turn-Around Time
There are no magical or visible signals to tell us, parents or pediatricians when the risk of facing forward in a crash is sufficiently low to warrant the change, and, when a parent drives around for months or years without a serious crash, the positive feedback that the system they have chosen "works" is very difficult to overcome. When in doubt, however, it's always better to keep the child facing rearward.
In the research and accident review(2) that I did a few years ago, the data seemed to break at about 12 months between severe consequences and more moderate consequences for the admittedly rare events of injury to young children facing forward that we were able to identify. One year old is also a nice benchmark, and the shift to that benchmark in the last few years has kept many kids in a safer environment longer and has probably saved some lives, some kids from paralysis and some parents from terrible grief.
Leg Length
As a side comment, some convertible child restraints indicate in their instructions that a child should face forward when his/her feet touch the vehicle seatback, or alternately when the legs must be bent. This prohibition is not justified by any accident experience or any laboratory evidence, and we are hoping that these instructions will soon be revised. The only physical limit on rear-facing use is when the child's head approaches the top of the restraint shell. At this point, s/he should be moved to a rear-facing convertible restraint, or, if the child is already using one, to its forward-facing configuration.
Parents and pediatricians need to know the real reasons for the current push to keep babies rear-facing to at least one year of age, in order to be able to make an informed judgment. Perhaps this will help spread the word.
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