A Beginner’s Guide To Car Seats – Second Stage

Beginners guide to car seats - stage 2

As your baby gets older and starts to outgrow their first car seat, it’s time to consider their second stage seat. With so many choices available, you may be left scratching your head as to where to start

Choosing a second stage car seat

When looking for your second stage seat, it’s important to remember that they’re all very different. There isn’t always a perfect car seat that will do absolutely everything you want. So start by creating a list of features you’d like. Then, decide on those that you prioritise the most and identify the areas where you’re willing to compromise.

Group 1

9-18kg (9 months to 4 years)

Pros Cons
  • Can be part of a modular system
  • Often forward facing only
  • Tailored to smaller age range
  •  Smaller age range
Britax Romer Duo Plus Group 1 ISOFIX - second stage car seat
Britax Romer Duo Plus Group 1 ISOFIX
Maxi-Cosi Pearl Group 1 - second stage car seat
Maxi-Cosi Pearl Group 1

Group 1 seats are often forward facing. If the seat you choose is R44.04 standard, this can be forward facing. Whereas, if your child is 9kg, or if the seat is R129 (i-Size) standard, then it is forward facing from 15 months onwards, regardless of weight.

Group 1 seats come either with ISOFIX built into them to connect directly into your vehicle (see my previous blog on first stage car seats for further information on ISOFIX), or they require a seperate ISOFIX base or can be installed with a seat belt.

Bases use a support leg for extra stability. Car seats with ISOFIX built in may use a support leg or a top tether. Before you buy, check your vehicle manual!

You may be wondering why I have listed a small age range as both a pro and a con. On the one hand, a small age range can be more tailored to a smaller stage of your child’s development. This means that it doesn’t need to adapt as much. On the other hand, you only get a few years use out of it, compared to the potential decade of use from the next type: a Group 1/2/3.

Safety Tips

Just like other seats, you’ll need to be careful to ensure the seat you choose is at the right angle for your child. You’ll also need to ensure that your little one is secured correctly using a 5-point harness or an impact shield.

There’s no conclusive answer as to whether a harness or impact shield is better in terms of safety. Some brands tend to prefer one or the other. You may lean more towards an impact shield if your child keeps slipping out of the harness. Impact shields are impossible for children to undo as they rely on the vehicle seat belt to keep them in place.

Cybex Juno M-Fix Group 1 - second stage car seat
Cybex Juno M-Fix Group 1 with impact shield

Just like a Group 0+/1 seat, you know when your child has outgrown a Group 1 seat due to the weight limit (18kg) and when their eyeline is out of the top of the seat.

One big issue for this type of seat is what’s known as ‘buckle crunch’. This is more prominent in cars with buckles that protrude out of the seat. After installation, if any part of the plastic belt buckle pulls against any plastic parts of the seat, it applies pressure and could shatter in a crash. Some cars, like the Nissan Qashqai, are notorious for buckle crunch issues, so it’s worth considering ISOFIX!

What to look for?

Modular system – if you chose to use an infant carrier, many now share a modular base with a Group 1 seat to help you to save money.

Recline – a recline can still be important if your child sleeps a lot or when you’re on longer journeys. Some Group 1 seats, particularly those with shields, may not have a recline.

Side Impact Protection –look for those with marked side impact protection. This is another sign of quality and offers more protection for your little one.

Group 1/2/3

9-36kg (9 months to 12 years)

Pros Cons
  • Great value for money
  • Forward facing only
  • Covers the child until they no longer need a seat
  • Large age range
Cosatto Hug Group 1/2/3 - second stage car seat
Cosatto Hug Group 1/2/3
Britax Romer Evolva Group 1/2/3 - second stage car seat
Britax Romer Evolva Group

Group 1/2/3 seats aren’t hugely different from Group 1 seats, but they’re often a bit bigger and can adapt to cover a child for longer. They also convert into a high-backed booster seat for use after the child has outgrown the restraint.

You won’t be able to buy an ISOFIX base separately if you change your mind and want one further down the line. So, looking at seats where ISOFIX is built-in is worth considering at this stage. Most ISOFIX model 1/2/3 seats use a shield rather than a harness, and those rare models that use a harness will use a top tether for a third point of secure contact to your vehicle.

Safety Tips

These models do not necessarily have a recline as standard, so ensure your child is at an appropriate angle so they’re not flopping out of the seat! The usual rules of ensuring the harness is at the proper height and tightness also apply.

Group 1/2/3 seats often fall into two varieties. They’re either better for younger children but not as great as a booster seat, or better as a booster but not as good for younger children. To provide an example, Recaro have two main models: the Young Sport Hero and the Monza Nova IS. The Young Sport Hero has a recline and a decent amount of padding but is small as a booster. On the other hand, the Monza Nova IS has no recline, a small polystyrene wedge for support and is identical to the brand’s main booster seat when the impact shield is removed.

Recaro Young Sport Hero Group 1/2/3 - second stage car seat
Recaro Young Sport Hero Group 1/2/3
Recaro Monza Nova Group 1/2/3 - second stage car seat
Recaro Monza Nova Group 1/2/3


It’s important to note that there are some exceptions to this. These seats are designed to be so adaptable they’ll cover every stage of development equally well.

Whichever type of restraint you choose, you can stop using it from 15kg, if your child is big enough to use a seatbelt securely so they don’t slip out from underneath it, or up to the maximum weight of 18kg. It’s then time to convert to the booster seat. This can involve removing ISOFIX, so as always; make sure you keep your instructions!

Your child will outgrow the seat either when they reach 135cm or 12 years of age, whichever comes first. They will then be fine to just use a seatbelt.

What to look for?

Recline – as this isn’t always standard, make sure you look at a recline. Some seats may only have one position that can only be used with the harness. Others will have multiple positions that can be used in both harness/shield and booster mode.

Side Impact Protection – this is important and should be used throughout the whole life of the seat. Sometimes, this can be quite bulky and can make putting multiple seats in a row more difficult.

Padding – plenty of padding that can be removed in various combinations as the child grows. Padding can keep them snug and supported through various stages of development.

Booster size – it’s worth checking what size the seat grows to in booster mode. Is it comparable to a booster, or a little bit on the small side?

If a seat has all of these things, then it’s generally providing excellent safety at all stages of use. Limited or missing features can mean it’s better in some areas and not others.

Which second stage car seat are you considering for your little one?

Mark Mushet

Mark Mushet has been with Uber Kids since the very beginning and spends most of his time writing for the website powered by an awful lot of caffeine! Having come from an independent local toy store, he’s been surprised to find he enjoys writing about car seats just as much as toys, and with an IOSH qualification in Child Safety Seat Awareness he knows a thing or two more than he expected, only being a “parent” to a Shorkie named Spud. He’s just waiting for the day he can stick a car seat in a spaceship.