HBB or FF 5 point for a 15kg child

[Somuchgoo]

My 5.5yo is 14.5-15kg (15kg in clothes on a good day, before a poo basically 😂). We've recently turned her round but she's getting near the height limit of her current seat. I wish we were still RF her, but we turned her on holiday as couldn't otherwise fit the car seat in, and now she won't go back.

With just a few exceptions, 5 point harnesses FF seats stop at 104cm (which sure is under, but not by much) and then it's either ERF or HBB. I understand that the current seats mostly go on height but weight, but I've also read the guidance behind the Regulations, and it's clear they go on height because parents are more likely to know their child's height, and because less children will be prematurely turned/put in HBB etc going by height (off the scale weight toddlers more common than really tall ones).

I've read that HBB is ok for over 15kg, but also that they shouldn't really be used under 18kg.

Having a HBB would be useful as we have an older child in one, and it makes it easier to give friends a lift etc, but I feel like my youngest is too physically small and I don't want to compromise on safety, unless it actually is as safe of course...

It's tricky.

I personally am happy to use the 5 point harness in a 123 type seat (e.g. Maxi Cosi Titan Pro, Britax Advansafix, Silver Cross Balance - and these are the 123 seats I'd use, preferably) over the 105cm, as long as the child is under the weight limit and physically fits well in the seat (and particularly if they are under 18kg).

I also noticed in the manual of my Britax one, it says when used in an i-size position it's 105cm/21kg, and when used in a non i-size isofix position, it's 18kg [no height limit]. Which makes absolutely no logical sense because there is no physical difference between i-size isofix and non i-size isofix (it's literally just the age of the car).

I do understand why they do it that way - it's under two different safety certifications - but it also tells me that using the seat without height limit up to 18kg is safe, regardless of the fact it is no longer certified once the child is 106cm+. (Worth noting if child is under 104cm and on a lower growth centile, the last 2-ish cm might take a lot longer than you think to gain.)

OTOH to continue using the harness is technically not a legal use of the seat and some people might not feel comfortable with that.

There are also 25kg harness FF seats from R44 so no height limit, like Joie Bold R (not i-Bold) or Cozy n Safe Hudson/Excalibur. (Not i-size). But the safety is likely not that great on these.

It might well be that the min limits are to do with avoiding switching at too early an age, so when your child is much older than the average but only at the minimum weight it's less of an issue. And it might be that the studies in the US which show 30lbs (13.5kg) is a much more vulnerable weight than 40lbs (18kg) are because of the fact more 30lb children will be under age 3 and more 40lb children will be over age 4. I can speculate on that but I don't know for sure.

Have you tried your DD in a HBB, maybe her sibling's? To see how it fits and how you feel about it.

Thank you.

I was considering the Bold, it's just so difficult to know whether that is going to be safer than one of the better HBB, given that the HBB isn't really designed for sometime so light.

I'm probably more than a little overprotective over her safety, she's had extensive brain surgery and health issues and I worry she wouldn't be as resilient in a crash. But I also appreciate that I can't keep her wrapped up in cotton wool forever.

She is tiny - she's gone under the bar in a roller coaster when braking, because she's that slight (fortunately small coaster and I was sat next to her to grab her). She's done a runner by rolling under toilet doors before 😂

I suspect her legs are longer proportionally then her torso. She needs 3-4 in length trousers but still wears Medium tops (we've just put away a 9-12m one - the length is time but the arms are too short).

She's currently in a britax romer dualfix (not isize).

Oh! Well if she's in a non i-size Dualfix, then there's no problem. She can stay in it until her shoulders don't fit under the headrest when it's at the highest position. There is no height limit on R44 seats, so it doesn't matter how long her legs are.

I do think the shell was quite short on that seat so that might happen earlier than in other seats, so you might want to look into 123 type seats anyway.

One feature to consider on high back boosters is the ones with a hook that goes between the legs almost like a strap for a 5-point harness. Britax Kidfix has this and Besafe izi Flex fix.

You could also speak to the In Car Safety Centre. They are experts in supporting children with all kinds of needs.