What is i-size, and why is rear-facing safer?

Baby Safety, Life with a toddler
We may earn money or products from the companies mentioned in this post.

Car seats are a huge minefield. There are so many car seat decisions – I-size, rear-facing, isofix… Some cheap, some very expensive, some colourful, some forward facing only, some rear facing only! The list of features goes on, but what I want to know is what’s the safest. What is I-size and why is rear-facing safer? Which will protect my baby, my precious little girl the most?

What is i-size and isofix, why is rear-facing safer Group 1 car seat

Here are the options as I see it…


You may wonder what’s so fab about isofix, why not just use the seatbelt?

What is Isofix?

Isofix attaches the car seat onto the car’s chassis, and it’s much less likely to be installed incorrectly. We tried our Maxi-Cosi Pebble with just the seatbelt and were shocked at how wobbly it appeared. It was also such a faff. Isofix is the safest option, it feels solid, and all we want is to keep our little baby safe. So isofix won. Yes it costs more, but if you can afford it, or compromise somewhere else then, put safety first, and isofix is by clear a worthwhile option.
What is i-size and isofix, why is rear-facing safer Group 1 car seat

Why is it hard to install isofix incorrectly?

On our Maxi-Cosi Family Fix base there are coloured lights which tell you when you’ve met all the criteria and it’s all installed correctly – the isofix points connected, the post is down correctly, and the car seat has been clicked in properly. I believe some other isofix bases and those by other manufacturers may have similar features, but don’t hold me to that! It’s a very useful feature though, and Maxi-Cosi have done it very nicely.



I-size looks set to?become regulation in 2017 or 2018 (I’ve read both but I can’t seem to see a confirmed date!), but what everyone wants to know is what is i-size?

I-size?car seats can fit in i-size compliant cars, these cars have isofix points and are listed by the manufacturer of the car seat as fitting that car.

What are I-size car seats:?

  • They use the child’s height instead of weight to determine fit – so it’s easy to know if your little one has outgrown their car seat
  • Must be used rear-facing until little one is 15 months old
  • Have additional safety measures including :
    • Isofix – a safety mechanism which means the car seat is less likely to be installed incorrectly
    • Additional safety testing including extra side impact protection

I found this?information here: http://www.i-size.org.uk and on the Which website here.


All the major manufacturers have I-size seats now and I’m sure the range will only increase with time. I hope the price of them comes down too, as they do seem to be more expensive, which is a shame given very soon most?car seats will be I-size.

This all makes sense to me, but I’m also confused. Yes,?i-size will be a regulation, but not all cars have isofix so seat belt car seats will still be made and used. Several car seats I’ve seen do rear-facing much longer than 15 months, and say they have side impact protection, but aren’t i-siize because they’re older. I really struggle with i-size because I really think if regulations are to specify car seats be used rear-facing for longer, they should be rear facing for longer than 15 months.


Rear or forward facing?

As part of I-size, rear facing will become compulsory until 15 months. However, regardless of i-size, given the statistics I have seen, I would be keeping H rear-facing anyway. Actually, she’s 14.5 months now and still rear facing in her Pebble. We plan to keep her rear facing as long as possible, much longer than 15 months. Apparently it’s five times safer for a child to be rear facing than forward facing (according to http://www.rearfacing.co.uk/facts.php)! Well that’s a statistic I can’t argue with!

I also can’t argue the fact that rear facing is standard in Scandinavian?countries until age 4 and in those countries there are a much lower number of children injured or killed in car accidents. e.g. between July 2006 and November 2007, no children under 6 were killed in a car crash in Sweden, in the UK, 21 are killed every year (and 205 injured) (http://www.rearfacing.co.uk/facts.php)
What is i-size and isofix, why is rear-facing safer Group 1 car seat

I completely believe this, however, I also read this article in The Economist, which tells a fuller story of Sweden’s road safety policies and their population as a whole. Car seats are not the only reason for their amazing?road safety statistics.


What about the ‘science’ and medical reasoning reasoning for rear-facing?

When in a crash while travelling forward, the car rapidly slows, but our heads can’t keep up with the sudden change in forces. As our head isn’t restrained by the seatbelt (or harness in the case of a little one) it keeps going forward, resulting in injuries like whiplash. Now, in an adult, our bones are quite hard and deal with this trauma much better than babies and toddlers, who’s bones are quite soft. Our bones break, so if a seatbelt crushes into them you might have some broken ribs, but your vital organs thy are protecting, are more likely to be fine. A little ones’ bones are not fully hardened til 2+. So, in a crash, if baby/toddler is front facing, it is up to their soft bones to protect them. Their neck and spine to stretch to with the forces that are acting, and to try to keep their head under control and not cause injuries; their ribs, which are much softer, to protect their precious organs. ?A little one’s head makes up a much higher proportion of their overall size and weight than ours which doesn’t help the matter.

If rear-facing, the little one’s head keeps travelling backwards into the car seat headrest which absorbs the forces, meaning little one’s head remains fully supported through the most dangerous part of the crash. It will then move forward to an extent, but without such an intense force.

In a forward facing seat the neck is subjected to a force equivalent to 300-320kg, while in a rear facing seat, the force on the neck is equivalent to 50kg. (quoted from?http://www.rearfacing.co.uk/facts.php)?


Scandinavian children are rear facing until they are 4?5 years old (25kg or 55lbs), which has resulted in a much lower number of children injured or dead in car accidents compared with other countries, as for instance the UK.


Well this is where we hit some problems, we bought the Maxi-Cosi Family Fix base (this one) and the?Maxi-Cosi Pebble Group 0+ Car Seat?before H was born, both of which we have loved. We meant to buy the 2-Way-Family-Fix base so we could then let H be rear-facing until 105cm by buying the 2-Way Pearl as her next seat. However, I think we should cut our losses, and keep H rear-facing as long as possible. Safety wins!

The stats I have seen indicate rear-facing is so much safer.

Why we’re choosing rear facing:

  1. five times safer
  2. Toddler H has only ever faced the back, so she doesn’t know any different
  3. The rear facing seats seem to have quite a bit of room
  4. If Sweden and other European countries can do it, why don’t we? Why don’t we embrace this safer option? Why have we held back? Why have these stats not been shared with us before?

The lovely Laura at Laura’s Lovely Blog wrote a post last summer on i-size and rear-facing which covers some of what I’ve written here, but please check it out too to see why her chosen car seat is the Maxi-Cosi 2-Way Pearl – check Laura’s post out here!

What do you think of rear facing car seats for toddlers?

Lynne x

Disclaimer: I have listed my sources, and where not listed this is based on my opinion. I am not medically trained or an expert in this matter or matters of the law, so please research this yourself and seek your own expert opinions before making any choices.?

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  • Reply
    Bear and Cardigan
    February 21, 2016 at 10:41 pm

    Couldn’t agree more about rear facing. We don’t have isofix but our car seat is suitable for rear facing up to approx 4 years old. Mum and Dad have the same so Bear will only know rear facing. I can’t understand why anyone would put their child’s safety at risk.
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  • Reply
    Mama, My Kid Doesn't Poop Rainbows
    February 22, 2016 at 10:57 am

    We’re still rear facing with our 19 month old and I will look for a rear facing seat for bigger toddlers when we move. Like you say safety is paramount and as he’s always been rear facing he wont know any different.

    Mama, My Kid Doesn’t Poop Rainbows recently posted…The #FartGlitter Linky: Week SeventeenMy Profile

  • Reply
    February 23, 2016 at 2:58 pm

    I really don’t understand why people forward face there children at young ages. The evidence is there to see and it’s better to be safe than sorry! #TwinklyTuesdays

  • Reply
    laura dove
    February 23, 2016 at 9:41 pm

    Rear facing has been proven to be the safest option, so really surely there is no other way?! #TheBabyFormula
    laura dove recently posted…For Eva, on your fourth birthdayMy Profile

  • Reply
    February 23, 2016 at 10:21 pm

    Thanks for sharing this. We’re just starting to look at the next size car seat up and this advise has certainly given food for thought. Thanks #fartglitter

  • Reply
    February 24, 2016 at 9:59 am

    We have an isofix car seat and agree that it is so much safer than using a seat belt. Little man is 18 months old and is actually now forward facing. He is way too big to be rear facing now in my opinion, and if he faced the back, there would be no where for his legs to dangle, so he would smash the back of the seat up in the back… #bestandworst
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  • Reply
    February 24, 2016 at 3:54 pm

    This is a really interesting post! Thank you for including statistics also. I don’t have children, and not planning on them any time soon, but this sounds like a fantastic purchase 🙂 xxxC #BloggerClubUK

  • Reply
    Sarah Howe (@RunJumpScrap)
    February 24, 2016 at 8:52 pm

    This is really interesting. We are in a forward facing with our little one right now but I never know if we will have another and may be referring back to this. Sometimes it’s a bit of a minefield. Thanks for sharing with #bestandworst
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  • Reply
    February 26, 2016 at 7:24 pm

    I love seeing posts about this stuff as it’s such an important subject that I strongly believe in. We are rear-facing Archie for as long as we can and I can’t wait for the law to change as it’s just so much safer. I feel so much better when driving to know that he is in the safest position possible. Thanks for linking up to #MarvMondays! Kaye xo

  • Reply
    Mrs H
    February 27, 2016 at 11:43 pm

    This is such an interesting post. As you say, the world of car seats is a mine field. And it does feel like the current advice and the laws are changing all the time. Our daughter is almost three and she currently uses a MaxiCosi Pebble fitted in to a family fix base. I have always loved the ease and safety of the family fix base. We are expecting another baby in July and ideally I would like to get a rear facing base. Or a base that can hold both rear and forward facing car seats. But it is so very expensive. It is great to hear all the proper guidelines. Thanks for sharing. #SundaysStars Hugs Lucy xxxx
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    • Reply
      February 27, 2016 at 11:56 pm

      Thanks Lucy. From what we’ve seen lots have built in isofix bases and some even work out cheaper. I also suspect the group 1 i-size and rear-facing seats will come down in price as more and more appear on the market, so you might have a better choice when it’s time for a group 1 seat x

  • Reply
    Mudpie Fridays
    February 29, 2016 at 8:50 pm

    Monkey is coming up 4 when we moved into the next size carseat there were very few rear facing seats on the market. I did the same research as you and discovered the same facts and decided I wanted to keep him rear facing. We opted for a Cybex as it was only one of 3 available and had the isofix where as the others didnt. Its good to hear regulations are changing here and that the manufacturers are catching on. Thank you for joining us at #BloggerClubUK hope to see you again this week x
    Mudpie Fridays recently posted…Preparing your first born for the birth of a siblingMy Profile

  • Reply
    Life as Mum
    March 1, 2016 at 7:38 pm

    I never did rear facing with my two girls cause it’s only recently I’ve really known about it all. But I will be doing it with baby boy who’s due in july.
    Thank you for linking up to #justanotherlinky
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  • Reply
    Something Crunchy Mummy
    March 2, 2016 at 8:10 pm

    Great post and so much information. Buying a car seat is a mine field with so many out there. #thebabyformula xx
    Something Crunchy Mummy recently posted…Monthly Bucket List – Update & March’s ListMy Profile

  • Reply
    Something Crunchy Mummy
    March 3, 2016 at 9:32 pm

    Popping back from #justanotherlinky. Thanks for linking up xx
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  • Reply
    April 25, 2016 at 6:42 am

    Thanks for this advice. I don’t have a car so now that Piglet has outgrown his Pebble I haven’t purchased another. This means no one can ever give us a lift though! I’m planning on learning to drive in the summer so after reading this I think I will definitely go for rear facing.
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