Booster vs harness for a 7yo--and does size matter?

I've seen a lot of threads recently with people stating that after a certain age, they feel kids are as safe, or possibly even safer in a booster vs a harness. I'm assuming that's due to concerns about neck loads. I'm wondering if anyone can point me to any information or links that would show how you're coming to your decision. My 7.5 yo is still harnessed in a Nautilus, though she rides in a booster in her Dad's car. We did just get a Vivo as our second backup booster, and at some point she will go into that in my car, but I don't know when. She's only just now moving to the last harness slots on the Nautilus, so she could fit in that for a long time. I feel like I understand the theory about neck loads in a harness in theory, but I don't understand why if it's safer for a 4yo, a 7yo (who would have a stronger bone structure) wouldn't handle those loads even better. Or is the thinking that if you could just get a 4 yo to sit perfectly in a booster, that would actually be better, but you can't, so a harness is better? What about side impacts? I can't imagine how a harness wouldn't be better that a 3-pt belt in that situation.

My other question, and it's the one that brought me to posting this today, is whether the child's size matters in making the decision, once they've passed 40 lbs and 6-ish years. I have a friend with a 6.5yo who is very thin and 45 pounds and rides in a booster. She was asking me last night about harnessed seats, because she feels like he would be safer if she put him back in one, with him being so slight. I told her if he stays in position while in his booster (she says he does), than the booster is probably just fine, but I also told her which harnessed seats would be the ones that would fit him. Any thoughts on whether a small 6.5 yo who fits his seat is any less safe in a booster than a larger one would be?

The only study I've seen talking about neck loads in kids in boosters shows an increased risk of neck injury for the under five crowd (http://www-nrd.nhtsa.dot.gov/pdf/nrd-01/esv/esv19/05-0330-O.pdf). Beyond that there is no data other than the carseat companies saying that their boosters (who I believe are tested with the six and ten year old dummies, does someone know?) pass testing within limits, so those dummies are safe in them. So without contradicting evidence to say that they're unsafe, we have to assume they're like anything else. Properly used for the proper child it's the right choice.

As for size, as long as the lap belt fits and the shoulder belt is appropriately placed, then a child of that size is ok. I've heard of a study (though I don't have a link to it) of kids under 40 pounds being more likely to submarine in a collision. Whether or not that's dependent upon the booster they're in (for instance, a 3 in 1 versus a Vivo) I don't know, but there was a decrease in submarining at 40 pounds.

My daughter is 7.5 and 43 pounds. So very slight. And she now rides boostered full time. She got to the point where even though she had 1/2" or so in the Nautilus harness, it was bothering her. And without evidence telling me she was safer, it got so that I was more annoyed with her complaining than I would be with her in a booster. I don't know that she's safer in a harness, but I know she's not unsafe in her booster. It's a high back and it fits her well.

I will put off a full time backless for as long as possible, given the lack of side impact, though she rides in one on occasion (a few times a year). Though it may come to be that studies show that it's just the videos that look scary, the load numbers are the same. Without standards and without companies releasing numbers anyway, we just don't know.

I think studies need to be done and data collected on this. Right now we cannot say that at six years and 45 pounds that one way is safer than another.

And of course this assumes the child can sit properly. At six years and not yet 40 pounds Piper would never have gone into a booster full time. Nevermind her age or her weight, she just had a nasty habit of being a backseat tech and saying, "You're not supposed to do *this*!" while we were driving along. Brilliant. So until she was trustworthy (and I spoke to her about this many times) she wasn't allowed.

Wendy

what matters partly is age... at age 6, the bones in the hips and spine are finally solid... the pics showing the comparison are still stuck in my mind from first seeing them (scanned by an anthropology student out of a textbook... they were black and white) on windsorpeak.com's carseat board.

what this does is two-fold... the hips being solid means the belt will be more likely to STAY on the hips.. not ride up... not let the child submarine out...

now of course, we still need the booster, as they aren't big enough to ensure this in just the seatbelt.

also, with the spine being solid, we don't see the floppy body when the child falls asleep... that limpness where the whole body would just flop forward... instead, only the head moves.. to the side or even back.. with the face pointing up.... keeping the child perfectly upright and still in their booster in proper position.... instead of needing the harness to hold them in position while they sleep.

beyond that, we move onto the head... at age 6, we're seeing a child whose head is much more proportional to his body... remember how big and heavy a child's head is compared to his body up till then?... again... still not quite the same as an adult, so we still need a booster.


we also know from research that kids under 40lbs are more likely to submarine out of a booster.

so my comfort zone for boosters is this...

whenever possible (I know some people are limited by what seats fit their child AND in their car with other kids in seats or by budget or all of those things), I prefer a child not to use a booster as a spare until age 5 AND at least 40lbs.

I do think that most kids, after reaching that, do need to be booster trained at some point after... because in emergencies and such, if one had to be used, you'd want them to know how... and then there are outings with friends, etc... where instead of moving seats around and knowing friends' parents often are more reliable when using boosters than on using a harnessed seat... it would be better to send a booster.

for primary seat use... I like 6 and over 40lbs... preferably at least 5lbs over the minimum weight (in the event of a bad illness, you don't want them dropping below the minimum weight of their seat)... for smaller built kids, though, you have to take practicality into it.

age 7 and around 40lbs is fine... age 8 and 35lbs is fine...

Some of the research that has been posted (which I hope others will post as I don't have the links) show that there is more loading on the neck from the harness keeping the child's body restrained and from the top tether than there is with a booster which moves with the child and allowing the body to move with the child.

I don't know why this is, but it's reason enough that I normally won't harness a kid over age 6... within reason... obviously size contributes.

I say normally, because there are exceptions... my oldest, I would have loved to keep him harnessed longer (he outgrew his regent at 6.5yrs) because he had a mild scoliosis... which caused him to flop horribly in my van in a booster. I was constantly watching him when we moved him... because his x-rays had still shown it there only a few months earlier...

miraculously, he had indeed outgrown it (couldn't be too surprised as it had made consistent progress in lessening, but still, you worry)... but had he flopped ONCE.. I would have had an 86-Y ordered and been using it with his booster in the center of my third row with the lap-only belt in a heartbeat.

I agree with everything Wendy said. :thumbsup:

We really don't have much information/data either way. My instincts tell me that harnessed is probably somewhat safer, especially in the more dangerous side-impact crashes, but really after 6 years/40 lbs. I'm fine with kids in boosters, provided they can sit properly and the booster fits them properly.

That said, my 8.5YO DS is still in a harnessed seat in our main car. There are several reasons for that - 1) I do feel that he's at least somewhat safer than in a booster 2) it's very, very hard to buckle a booster when we have three seats in our Focus 3) he prefers it! If he strongly desired a booster or complained about the comfort of his harnessed seat, I'd probably make the switch. As it is, we're going to stick with our current setup until the end of the school year (he has to be able to buckle quickly in the pickup lane after school) and then will move him to a booster in my vehicle.

Kat_Momof3 said:

what matters partly is age... at age 6, the bones in the hips and spine are finally solid... the pics showing the comparison are still stuck in my mind from first seeing them (scanned by an anthropology student out of a textbook... they were black and white) on windsorpeak.com's carseat board.

also, with the spine being solid, we don't see the floppy body when the child falls asleep... that limpness where the whole body would just flop forward... instead, only the head moves.. to the side or even back.. with the face pointing up.... keeping the child perfectly upright and still in their booster in proper position.... instead of needing the harness to hold them in position while they sleep.

beyond that, we move onto the head... at age 6, we're seeing a child whose head is much more proportional to his body... remember how big and heavy a child's head is compared to his body up till then?... again... still not quite the same as an adult, so we still need a booster.

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I've always heard that hip bones ossify at puberty. The spinal column does ossify somewhere between the ages of 3-6, differing by child. I'm not sure where "floppy body" comes into this because that's an issue of muscle tone, not spinal column ossification. When you sleep, your muscle tone relaxes and you go floppy. Kids will flop forward based on the angle of the back seat and how the booster is positioned on it. But we've gotten off the OP's original topic.

I think that harnessing or boostering once the child has reached booster maturity and min. weight limits (age 4-6 and 40 lbs.) is the parent's choice. Researchers haven't looked into harnessing vs. boostering big kids here because it's a new phenomena: we haven't had mareketable HWH seats until the last 6 years and boosters have really only been on the market for the past, what, 12 or so years? And what percentage of kids were actually riding in them until recently?

Clearly harnessing is superior at containing a child in side impacts: the child is secured better and the carseat helps absorb crash forces. In a frontal impact, a seat belt may allow extra movement that reduces neck load on the child. But, that extra movement may allow the child to hit the front seat or a structural pillar of the vehicle. It all goes back to the need for NCAP testing of carseats I think.

Thanks for the replies so far. So far, it's sounding like there may not be any information that really backs up the feeling that some people have that after a certain age (Kat mentions 6yrs and 40lbs), it is better for a child to be in a booster rather than a harness. There's nothing to say it's not better, either, but I've just been trying to figure out if there's compelling data out there that would suggest it would be better for my 7yo to move out of her harness and into a booster. She's perfectly happy in it, and I'm perfectly happy to have her in it, so I don't see a reason to make a change yet unless there is more to suggest that a booster is safer than there is to suggest a harness is safer (I know both would be "safe" for her at this point, I'm just trying to choose the best). It still seems to me that if kids under 5 have increased neck loading in a booster vs a harness, that an older child with a relatively smaller head would fare better in a harness as well. I don't understand why when they get older, those neck loads would suddenly be more, and more of a danger.

Kat_Momof3 said:

what matters partly is age... at age 6, the bones in the hips and spine are finally solid...

Click to expand...

The issue with the hip bones is not how solid they are, but rather how fully developed they are. From the CPST manual (p 123): "The child’s pelvis is small, rounded, and not fully developed until puberty. This is important to know because the lap belt does not always stay below the hip bones in pre-school or elementary school age children."

This article cites an older version of the CPST curriculum and says, "The iliac crest does not develop until a child is approximately 10 years old. Consequently, the lap belt does not reliably stay below the iliac crest, and can contribute to abdominal injuries (NHTSA, 1997). "

I think older kids can sleep better in boosters because their heads are proportionately smaller, not necessarily because of spinal development. This page has pictures of the proportional development of the head and body, and of the spinal ossification process... http://www.carseat.se/rearfacing/safety-benefits/

The short answer is that high back boosters are as safe or safer than harnessed FF seats for kids 4+. Contrary to popular opinion there is no data, statistics, research or real life experience which show harnessing older kids is better than high back boosters.

People who work with car seats professionally, not just sales but the whole spectrum, know both methods offer similar safety. There is great debate regarding HBB vs. harness for older kids on forums but not among people who work with these issues. The amount of people who are really knowledgeable of the whole car seat spectrum (testing, developing, standards, type of seats, children's bodies, research, medical issues, technical specs, etc.) is small. I have the great privilege of working and talking to some of these people. HBB vs. harnessing is not discussed since everyone know they both offer similar safety. The group of elite car seat researchers/people etc is small even when looking globally.

There is no testing between the two methods since it's too subjective, expensive and complicated. Opinions are therefore subjective and rely much on experiences in the field. As some know Sweden recommend not harnessing kids 4+, and of course Rf to at leas age 4, due to safety. This is partly based on testing but also on all accumulated experiences from the researchers. Just how safe it is is also backed up by the data during many years.

Sweden is 30 years ahead in car seat safety and keeping kids safe in cars so it think it's a good idea to consider those opinions.

Both harnessing and HBB offer good protection although rear facing a 7 year old offer a large safety advantage (but it's not practical). If a child is happy in a harnessed seat I see no reason to change to a HBB purely for safety reasons.

Clearly harnessing is superior at containing a child in side impacts: the child is secured better and the carseat helps absorb crash forces. In a frontal impact, a seat belt may allow extra movement that reduces neck load on the child. But, that extra movement may allow the child to hit the front seat or a structural pillar of the vehicle. It all goes back to the need for NCAP testing of carseats I think.

Click to expand...

Harnessing is not superior in side impact collisions.

what matters partly is age... at age 6, the bones in the hips and spine are finally solid...

Click to expand...

Bones are not solid at age 6, the ossification continues until puberty. The iliac crest is very important and is nowhere near done with development at this stage.

Weight of a child is not really of importance. The 40 lbs limit in many US states is not a magic number. A normal 35 lbs child is just as safe as a 45 lbs child.

Like Wendy said, belt fit is extremely important.

HBB offer some advantages which can be crucial and lead to large safety advantages. Those are simple things such as cost of seat, ease of installation, moving seat between cars and simplicity.

see, this is why I normally wait before replying... but I was having one of my less ditzy days and still managed to fudge up some things.

Sorry all!

Anyway.... while most of us disagree with age 4 being fine... mostly due to maturity... I still stand by age 6 being the same and much less difference.

I think all you can do at the end of the day is do the best you can with the seats on the market, what fits in your vehicle and fits your child.

And obviously, if a child shows an obvious preference after about age 6, I'm inclined to follow it, because that's an age where not only do they have definite and sure opinions, but those opinions usually affect their behavior.

I'd rather a happy 8yr old in a harness over an unhappy one in a booster... just as I'd rather a happy 8yr old in a booster over an unhappy one in a harness.

at 4-5, I say give them a say on rearfacing/forward facing... and age 6.. some say (how much depending on maturity and all that) about harness/booster.

Adventuredad said:

The short answer is that high back boosters are as safe or safer than harnessed FF seats for kids 4+. Contrary to popular opinion there is no data, statistics, research or real life experience which show harnessing older kids is better than high back boosters.

People who work with car seats professionally, not just sales but the whole spectrum, know both methods offer similar safety. There is great debate regarding HBB vs. harness for older kids on forums but not among people who work with these issues. The amount of people who are really knowledgeable of the whole car seat spectrum (testing, developing, standards, type of seats, children's bodies, research, medical issues, technical specs, etc.) is small. I have the great privilege of working and talking to some of these people. HBB vs. harnessing is not discussed since everyone know they both offer similar safety. The group of elite car seat researchers/people etc is small even when looking globally.

There is no testing between the two methods since it's too subjective, expensive and complicated. Opinions are therefore subjective and rely much on experiences in the field. As some know Sweden recommend not harnessing kids 4+, and of course Rf to at leas age 4, due to safety. This is partly based on testing but also on all accumulated experiences from the researchers. Just how safe it is is also backed up by the data during many years.

Sweden is 30 years ahead in car seat safety and keeping kids safe in cars so it think it's a good idea to consider those opinions.

Both harnessing and HBB offer good protection although rear facing a 7 year old offer a large safety advantage (but it's not practical). If a child is happy in a harnessed seat I see no reason to change to a HBB purely for safety reasons.



Harnessing is not superior in side impact collisions.



Bones are not solid at age 6, the ossification continues until puberty. The iliac crest is very important and is nowhere near done with development at this stage.

Weight of a child is not really of importance. The 40 lbs limit in many US states is not a magic number. A normal 35 lbs child is just as safe as a 45 lbs child.

Like Wendy said, belt fit is extremely important.

HBB offer some advantages which can be crucial and lead to large safety advantages. Those are simple things such as cost of seat, ease of installation, moving seat between cars and simplicity.

Click to expand...

I wish these experts would write some papers on their findings on the differences between harnessing and boosters. It's frustrating from our standpoint of trying to figure out what really is safer. It's great that a really small group of people think boostering is just as safe as harnessing, but where's the proof? I'm not opposed to boosters--my ds started in a booster at 4.5 and 50 lbs. (I think) and my dd was 40 lbs. (can't remember how old, either 5 or 6).

I'm specifically interested in your statement about how harnessed seats aren't any safer in side impacts. Again, because there aren't any studies that I've seen to show otherwise, why wouldn't a harnessed seat be a better choice for a side impact (assuming you could choose your crash)? The body is held in place and not thrown around and the carseat tends to be more encompassing than a booster, given the types of boosters on the market in the U.S.

murphydog77 said:

I wish these experts would write some papers on their findings on the differences between harnessing and boosters.

Click to expand...

Right. It doesn't really help me any to hear that some experts in another country say it's so, so it's so, kwim? I was curious if there is any actual data out there that was what had tipped some people here in the direction of feeling that a booster is actually safer after a certain age (which is what I'm specifically getting at, since I have read it from a number of people). So far it sounds like their just isn't any real data out there, and there isn't a good reason to choose one over the other at this point, so it's up to the parent.

I think a child of 6-7 should be booster-trained, because there's a pretty good chance that the child will need to use a booster for carpools or playdates. I agree that there's no evidence either way and unless there's startling new evidence, I'm comfortable concluding that both are safe and appropriate choices if they can be properly used.

Adventuredad said:

The short answer is that high back boosters are as safe or safer than harnessed FF seats for kids 4+. Contrary to popular opinion there is no data, statistics, research or real life experience which show harnessing older kids is better than high back boosters.

Click to expand...

But are there any studies or data which show that HBBs are safer for older preschoolers than harnessed FF seats are? Because "there isn't any data" means "we don't know for sure" not "the opposite is true". Further, "that's how Sweden does it" isn't a legitimate argument for the safety of any practice. Crash statistics and testing data are much more relevant when it comes to safety.