Why Rear Facing: the Science Junkie’s Guide

If you’re looking for just the facts about rear facing versus forward facing, you’ve come to the right place. There are multiple factors involved in this discussion; the unique physiology of a young toddler combined with the type of force in the most severe crashes adds up to the perfect storm that puts kids at significant risk if they are forward facing too early.

First, let’s explore the difference in anatomy. Toddlers are not just small adults; their bodies are still developing and those developmental changes make them more vulnerable than an adult. A toddler’s vertebrae are connected via cartilage rather than ossified bone. Those connections are called synchondroses, which are slowly closing over time. There are three major points of ossification, each with two synchondroses. According to a study published in the Association for the Advancement of Automotive Medicine, the first station to close is the C3, second is the axis, and third is the atlas. The results of the study show:

  • 50% probability that the primary closure of the C3 is complete at age 2 and the secondary at age 3.
  • 50% probability that the primary closure of the axis is complete at age 5 and the secondary at age 6.
  • 50% probability that the primary closure of the atlas is complete at age 7 and the secondary at age 8. 1
Vertebrae age 1 and 6 rear facing

Vertebrae age 1 and 6 Photo Credit: White, T. Human Osteology, 2000

This image to the right shows the cervical (top), thoracic (middle), and lumbar (bottom) vertebrae of a one year old (left, each photo) and six year old (right, each photo). Note the easily visible synchondroses in each.

These findings show that before age two, none of the cartilaginous spaces have completed ossification. Those pieces of cartilage have the ability to stretch up to two inches. Yet only 1/4″ stretch is enough to rupture the spinal column, resulting in paralysis or death. 2





why children should rear face

Image Courtesy of Securatot UK

Additionally, a child’s immature spine is responsible for supporting a much larger proportion of body weight than an adult’s more mature spinal column. The average nine month old child’s head makes up 25% of his body weight; while an adult’s head only makes up 6% of its body weight. 3  This difference in proportion only adds to the need to safeguard the spinal column.

Second, let’s talk crashes. According to NHTSA, roughly 60% of vehicle crashes are frontal impacts and 20% are side impacts. During a crash, occupants will travel towards the point of impact, putting all the stress on the neck and spine. At that moment there are actually three impacts: the vehicle striking whatever it strikes, the body of the occupant being retained by the seat belt or harness, and then the internal organs striking the front of the inside of the body. When someone is rear facing, crashes two and three occur in concert and the forces of the crash are more equally diffused along the shell of the seat, holding the neck and spine in line.

The American Academy of Pediatrics recommends rear facing until a minimum of age two, based on findings published by BMJ Injury Prevention. This study compared injury statistics for 15 years worth of crashes involving children under age 2. Researchers compared the injuries sustained by the children in crashes and found “the odds of severe injury for forward-facing infants under 12 months of age were 1.79 times higher than for rear-facing infants; for children 12 to 23 months old, the odds were 5.32 times higher.” 4

Why the recommendation to rear face until a minimum of age two? Presently, the only data with hard numbers comparing injury when rear versus forward facing are centered around that age group. However, age two is truly a bare minimum. According to the previously noted study, at age three there is still only a 50% probability that the C3 vertebra has finished ossification. The older a child gets, the more time their spinal column has to strengthen and the reality is the longer, the better. Most car seats on the market today will easily rear face even above average height and weight kids until 3-4 years of age. Without a CT scan, there is no way to know what stage of development your child’s spinal column is in, so the safest option is to rear face to the maximum weight or height of a convertible car seat. As time goes on and more older children are rear facing, there will be more scientific data to compare the benefits of a rear facing car seat for preventing spinal injury.

Rear facing is not a choice to be made based on parenting style or opinion; it’s one based on scientific fact. The more we know about crashes, the better we’re able to protect our kids from severe injury as a result of a crash.



  1. Narayan Yoganandan, PhD, Frank A. Pintar, PhD, and Sean M. Lew, MD.  Ann Adv Automot Med. 2011 October; 55: 159–168.http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3256844/
  2. Brockmeyer, Doug MD, Pediatric Spinal Cord and Spinal Column Trauma http://www.neurosurgery.org/sections/section.aspx?Section=PD&Page=ped_spine.asp
  3. Thomas Turbell, VTI (Swedish National Road and Transport Research Institute) http://www.rearfacing.co.uk/expertquotes.php
  4. PEDIATRICS Vol. 121 No. 3 March 1, 2008 pp. 619 -620  (doi: 10.1542/peds.2007-3637) http://pediatrics.aappublications.org/content/121/3/619.full

18 thoughts on “Why Rear Facing: the Science Junkie’s Guide

  1. Pingback: Rear Facing Car Seat Myths Busted | Car Seats For The Littles

  2. Pingback: Evenflo Sureride Convertible Seat: a mini review | Car Seats For The Littles

  3. Pingback: Graco MyRide 65 Convertible Car Seat Mini Review | Car Seats For The Littles

  4. Pingback: The Four Steps of Car Seat Safety | Car Seats For The Littles

  5. Pingback: How much Headroom? A Height Comparison of Rear Facing Convertible Car Seats | Car Seats For The Littles

  6. Pingback: The Ultimate Car Seat Guide for New Parents | Car Seats For The Littles

  7. Hi! I am sorry to post a random question on a themed post, but I am in need of some help. My family just had a massive vehicle catastrophe and we had to move from a Dodge Caravan to a Nissan Versa. We currently have our children in a Graco Argos and a Graco Nautilus. Do you know of any more inexpensive car seats with a base slimmer than 17inches?

  8. Pingback: Evenflo SecureKid Review | Car Seats For The Littles

  9. Thank you for your article (“Why Rear-Facing..”) and for your references. I found reading through your Works Cited list very helpful and informative. I am a mother of a 2 year-old boy and I have just turned him around to face forward in our SUV as he was uncomfortable rear facing and often screamed. I thought that at two years old he was now in the safety zone to be moved. I am now going to move him back to RF again and see what I can do to get around some of the problematics of RF, i.e. finding a carseat to best fit him, working through his screaming fits, ..etc. Our screaming situation is not yet as extreme as others who have posted their struggles here. Looking through your research I see why it is so important to switch back!

    I did want to add that had I not looked at this article and your references and instead had just read your other post “Rear Facing Myths Busted” I would likely have not decided to switch back. This site certainly seems to have only the best intentions in protecting children. But the rhetoric in “..Myths Busted” is frustrating.

    I’ve copied below a few of the statements that were most irritating in the tone used. For many parents, myself included, it is simply not true that children are happy to have their legs rearranged up against the back seat, that they really don’t care about this arrangement, or that they are screaming because the sky is blue and not because they are uncomfortable.” These lines belittle parents who have dealt with some very wild temper tantrums on the road because their kids were uncomfortable in certain rear facing positions. (And yes, my child did completely stop rioting when I switched him to forward facing.) And these temper tantrums are so hard on parents, particularly those of us that for whatever reason cannot tune it out as well as others, and are also driving often and for long distances.

    Nevertheless I am going to switch my son back to RF after reading this article because the research supports that in general in most situations that is the safer choice. And I appreciate the suggestions you gave for how to best work with children to feel comfortable when RF. Certainly I am better educated about this data after coming to your site. Truly, I thank you for the info!

    But I do think the writers of the other post should rethink some of the language used. Offending or irritating a significant portion of your readers and starting such a heated debate seems so unnecessary and so against your purpose of informing folks to “do better”. Simply qualifying some of your statements (copied below), acknowledging stressful situations that make RF challenging, and then offering immediate, accessible, and provocative statistics as support for working to overcome these challenges would have resonated I imagine so much more successfully with so many of your readers who grew quite angry over the argument presented.

    All of that said, and nit-picking aside, I appreciate that I know better now. And to paraphrase your own comments– now I can do better as well. I’m grateful to you and need now only to show this research to my husband when he thinks we’re crazy to again RF:)

    Sample Quotes:
    “Here’s another long legged three year old in a seat that is well known for limited rear facing leg room –…. She is happy to cross her legs, prop them up on the seat back, or hang them over the sides of the seat. ”

    “It may seem incredibly uncomfortable to think of sitting with legs crossed or propped up for an extended period of time as an adult, but toddlers and preschoolers just really don’t care.”

    “This little one is 35 months, 30 lbs and 35″ in a Diono Radian Rear Facing Car Seat Myths Busted. She slept through her family’s entire day trip without a peep, safely buckled in rear facing. Clearly she is tremendously uncomfortable!”

    “Toddlers rarely scream in the car because rear facing is terrible – it’s just as likely they’re screaming because the sky is blue, their cereal was in the wrong bowl at breakfast time, or they just plain don’t like being restrained, regardless of the direction they’re facing.”

  10. Pingback: safety is my middle name | Thoughts and Musings

  11. Pingback: CAR SEAT SAFETY! What you NEED to know!!! | Mama Bree

  12. I appreciate this website and the great information, I have a 3 1/2 yr boy who has been FF since 14 months and in a Graco Argos seat we have really loved, easy to install, all this RF for longer info is new to me, and I’m just learning about it. I have a second child who is approaching 1yr old and is already 20 lbs, I’ve been looking in to car seats for him to switch to, I was thinking forward facing seats but I wouldn’t now after all this great info. Also he is going to have spinal surgery in a couple months, so with his condition RF as long as possible. I still have not decided on a seat but am considering Graco fit4me. I’ve been very happy with graco products we have used the infant seat snug ride 35 for both babies now, and thrilled with it. My concern for my 31/2 yr old is he’s thin and tall but would fit RF requirements, how ever his car seat does not. And it was expensive around 200 dollars. And he’s been FF for a year and a half I don’t think I could afford a new seat, and don’t think he would tolerate it. However the baby will def remain RF as long as possible. I wish vehicles would support RF and put DVD players in position there so kids can see that direction. I don’t love screen time but if kids have to face that way, they may be happier with something to watch or look at. Just my opinion

  13. Even in a rear-impact crash, from the way I understand it, most of the forces are still pushing toward the front of both cars. In this case, rear-facing would still be safer.

Comments are closed.