Safety Archive

Should You Really Be Concerned about Harness and Seat Belt Geometry?

A common question parents ask is whether or not the buckle should be sitting so high on their child after he’s buckled in the carseat. Caregivers may have heard that the buckle should fit low on the hips, like a seat belt, or have seen that the harness fits their child differently than their friend’s child who rides in a different carseat.

The simple answer is that harness geometry differs by manufacturer and may even differ within that manufacturer’s line. The lap portion of the harness may ride higher on your child’s belly in your rear-facing infant seat whereas it sits lower across his thighs when he rides in his convertible seat made by the same manufacturer. Any insert that comes with the carseat will also affect whether the straps cross your child’s thighs or his hips.

The harness may also sit quite differently on a newborn than it does on a larger child because a newborn has skinnier legs. Manufacturers certify their carseats to fit a wide range of weights and all children are proportionally built differently.

The harness also serves several purposes: it restrains a child in a crash, contacts the strongest parts of the body (the bones), spreads out the crash forces over a large part of the body, helps the body ride down crash forces, and protects the head, neck, and spinal cord. The direction the carseat faces plays a role too; a buckle sitting high on a child’s belly plays less of an injury role on a rear-facing carseat because the carseat itself is bearing the brunt of the crash force as are the shoulder straps.

One feature being provided by manufacturers that can greatly change the way the harness sits on your child’s legs is crotch strap length adjustment. Clek’s innovative way of adjusting crotch strap length is to provide two straps of different lengths on one buckle (see pics below). Baby Trend infant seats have adjustable crotch straps and require the buckle latches to be ½”-1″ from the baby’s thighs. Other manufacturers allow the crotch strap to be routed back through the outside slot, which greatly reduces the length and brings the harness down on the thighs.

The one place where harness fit counts is in the shoulder slot height. When your child is rear-facing, the straps must be at or below her shoulders. Why? The majority of crashes are frontal crashes and in all crashes, everything, including your child, will move toward the point of impact. Your rear-facing carseat will dip down and allow your child to slide up the seat. If the harness is positioned above her shoulders, she’ll slide up until she reaches the harness. Then on rebound—after the crash happens and everything that moved toward the impact comes back and settles—your child will slide back down in her seat. That’s a lot of movement and potential for injury, so keeping her down in her seat in the first place is important.

When forward-facing, you want the straps to be at or above her shoulders to hold her back in a crash. The carseat will again move down and toward the front of the vehicle. If the slots used are below her shoulders, possible spinal compression can occur as she’s held down and her shoulders roll forward.

So, for harness use, as long as the shoulder slots are properly positioned, everything else is good (as an end-user, you can’t really redesign where the lap straps are coming out of the carseat anyway). What about belt-positioning boosters and seat belts? Doesn’t using a belt-positioning booster automatically mean proper seat belt positioning?

No.

With boosters, you want the lap portion of the seat belt to fit low on the hips, touching the thighs—and there’s quite a range of what that means. Clothing can get in the way of seeing where the belt actually lies on the lap, so when assessing lap belt fit, it’s good for the child to be wearing snug-fitting clothing. The shoulder belt should be squarely on the shoulder—closer to the neck than the edge of the arm where it may slide off. It should also be noted here that since your child won’t always be wearing snug-fitting clothing, when she’s wearing jeans or other bulky clothing, she should be taught to pull the lap belt snug and low on her hips after buckling.

Younger children tend to have narrow torsos, so getting proper shoulder belt fit on them is more difficult because there’s no room for the seat belt. For a narrow kid like this, it’s better to have the shoulder belt closer to the neck—but not over the throat—so that in a crash, the child can’t slip out of the shoulder belt. Adjusting the headrest up on the booster sets the shoulder belt closer to the neck. The child below shows that she’s too small for a backless booster; she should ideally be in a harnessed seat or at the very least a highback booster so the shoulder belt is positioned better on her. A shoulder belt positioner attached to a backless booster can help too, but not as well as a highback booster. The seat belt is also not adjusted securely on her.

The lap belt portion of the seat belt should be touching or partially laying on the thighs. It can be too far forward on the thighs, which can lead to sliding (submarining) under the seat belt in a crash, and of course, it can sit too high on the soft belly, where injury to internal organs can occur in a crash.

Of course we can’t forget about the big kids who fit into seat belts. How do you know if your child is big enough to fit into a seat belt without needing a booster seat? There’s an easy test, called the 5-Step Test which allows you to tell if your kid still needs a booster.

5-Step Test

1. Does the child sit all the way back on the vehicle seat?
2. Are his knees bent comfortably at the edge of the vehicle seat?
3. Does the seat belt cross the shoulder properly on the center of the collar bone?
4. Is the lap belt low, touching the thighs?
5. Can the child stay this way for the entire ride?

Vehicle seat belts are designed to fit adult males, not children. It’s not safe for them to sit in one unless it fits them well; they’re at risk for seat belt syndrome, serious head injuries, broken bones, and death. Most kids won’t fit in a seat belt without a booster until around ages 11-12.

Another summer and kids are starting to die almost daily because the temperature is heating up and what didn’t injure them earlier in the year is lethal now. Last week alone, 4 children died from being left unattended in hot vehicles. To date, 12 children have died in 2018 from being left in vehicles; outside temperatures ranged from 81° to 99°, though in previous years, children have died when temps have been in the 60s and 70s. Children’s body temperatures heat up 3 to 5 times faster than adults’ so organ damage can happen quickly.

A vehicle’s interior can increase in temperature by 19° in 10 minutes and go up another 10° after another 10 minutes. Within only 20 minutes, your car’s interior temp has increased by 29°—if it started at 70°, it’s now 99° and roasting. It’s only up from here.

It’s easy to make parenting judgments about the parents who left their children in vehicles, how awful they are and that they should never have been parents in the first place. But there is science behind how the brain works and how it can forget really important things—like kids—when it has been stressed or exhausted or out of a routine. If you aren’t the first to realize your brain may react this way, your child is at risk too.

Here are 10 important tips to help prevent more tragedies:

1. If your child is missing, check your pool first, then your vehicle (including the trunk!)—check neighbor’s pools and vehicles second.
2. Arrange to have your childcare provider contact you when your child doesn’t show up that day. Make sure they have multiple contact numbers to call/text and that they keep calling until they reach a live person.
3. Keep all vehicles LOCKED at all times, even when they are in the garage and keep your keys/key fobs out of reach.
4. Keep your wallet AND cell phone in the back seat when you are driving.
5. Utilize available technology: Some Evenflo carseats, the Cybex Sirona M, and the Baby Trend Secure Snap Fit have technology available to let you know if your child has been left in the carseat. Some vehicles also have backseat reminders, and Hyundai is anticipating adding a rear seat sensor system in some 2019 model year vehicles.
6. Another option, put one shoe in the back seat when you are driving—you’re not going to walk away from your vehicle without your other shoe!
7. Make it a habit to always look in the back seat when getting out of the car.
8. Teach your children that it’s NEVER okay to play in the car or to go into the car to get something without a grown-up.
9. Teach your children NEVER to hide in the car or inside the trunk.
10. However, also teach your children to blow the horn repeatedly to attract attention if they are ever trapped inside a vehicle.

And don’t forget about pets and the elderly! All of these populations have bodies that heat up faster than healthy adults and they cannot handle the heat as well. We may intend to run into the store for only 5 minutes, but circumstances may change and that quick trip may end up taking 15 minutes. It’s better to err on the side of safety and not risk a life.

Infographics provided by noheatstroke.org, run by meteorologist Jan Null. He keeps this website up-to-date with the sad statistics and other scientific data regarding hot vehicles.

Putting a newborn baby in a car seat is daunting even in the best of circumstances. They are just so tiny and fragile, the buckles on the seat seem so huge and it often feels like you’re just going to smush (technical term) their insides when you tighten the harness. As they grow, they feel less breakable, but it seems there’s always something new to worry about when it comes to car seats.

One of the most common questions I see on parenting and car seat groups is regarding head slump, typically in forward-facing kids or in older rear-facing children. There are new aftermarket products coming out each day to address this issue, but as a Pediatric Physical Therapist and a CPS Technician, I have some grave concerns that these “solutions” to head slump might be much worse than the problem itself.

What is head slump?

You know when your husband sits next to you on an airplane and immediately falls asleep while you are stuck alone, anxious and bored out of your mind for the next 3 hours? (No? Just me?) Well, that moment when they’re so deeply enjoying their abandonment nap that their head falls forward is “head slump”.

Head slump is when the chin moves towards the chest in a moment of forward flexion of the cervical (upper) spine. It is most common when a person is sleeping upright, and to an adult, it’s pretty uncomfortable. Adults are not terribly flexible and some of us carry a tiny little bit (okay, a ton) of tension in our necks. But thankfully, our kids don’t. Their necks are more mobile than ours and much less prone to tightness from tension, so the forward flexed head isn’t usually painful for them. The person sleeping on the airplane isn’t in any danger from their head slump position and likewise, for most kids, it’s really a non-issue.

When is head slump something to worry about?

The first and most common scenario where head slump is a real problem is in a newborn. The airway in a newborn baby is tiny, about the diameter of a drinking straw, and often it’s a little more flexible than an adult’s, meaning it’s easier to partially block or collapse. Another reason head slump can be concerning for a newborn is that they may not have the neurological drive to reopen their airway. That is, their brain may not be developed enough to realize that it’s being deprived of oxygen or to tell the muscles to do something about it. Finally, because newborns have proportionally large heads on tiny neck muscles, even if they have the drive to lift their heads, they often lack the strength to make that lift against gravity.

Image from Journal of Emergency Medical Services

The other situation where head slump is a concern is in older children who do not have adequate head control. These are typically children with medical diagnoses of some sort and the problem is essentially the same as in a newborn – if a child cannot lift and maintain their head upright against gravity, then they need to be positioned to make sure that head slump does not occur. The same goes for babies with tracheomalacia, where the trachea is not as rigid and may be more prone to collapse.

These two groups aside, head slump is not a problematic position for typically developing children and older babies. These children have wider airways, the ability and awareness to lift their heads if they’re not getting adequate air, and the position itself isn’t inherently dangerous for the neck. There’s not a universal age where this happens, but once baby can fully lift their head and hold it up to look around for a few minutes during tummy time, they’re likely in the clear.

What should you do about head slump?

The Ford Motor Company is recalling 1.3 million Ford Fusion and Lincoln MKZ vehicles because the steering wheel can come loose and can potentially fall off while being driven.

The recall applies to certain Fusion and MKZ vehicles from the 2014-2018 model years:

• 2014-2017 Ford Fusion vehicles built at the Flat Rock Assembly plant from August 6, 2013 to February 29, 2016
• 2014-2018 Ford Fusion vehicles built at the Hermosillo Assembly Plant from July 25, 2013 to March 5, 2018
• 2014-2018 Lincoln MKZ vehicles built at the Hermosillo Assembly Plant from July 25, 2013 to March 5, 2018

The location and date of manufacture can be found on a sticker inside the driver’s door frame.

The cause of the recall is a potentially loose bolt in the steering column. Dealers will replace the existing bolt with a more secure one. According to news reports, the company is aware of at least two collisions and at least one injury resulting from this problem.

Ford’s recall notice can be found here.