The 2-hour car seat rule - what you need to know

Between 2004 and 2008, a total of 31 children under the age of 2 died due to suffocation or strangulation while sitting in a car seat for extended periods of time, according to a 2015 study published in the Journal of Pediatrics.¹

This is why experts advise that a baby is not kept in an infant car seat for longer than is necessary.

What the research says

A study from 2016 funded by the Lullaby Trust and conducted by researchers at Swindon's Great Western Hospital, the University of Southampton and the University of Bristol, has recommended parents do not keep infants or babies in car seats for long periods of time.²

That's because, as well as being in a scrunched position, the movement of the car while travelling also has an impact on babies while in car seats. Previously, safety tests did not take into account the angle a seat will sit at while in a car, or the vibrations of the seat while in motion.

Using a motion simulator (and 40 babies in the car seats) they replicated a 30mph car journey to reproduce vertical vibration — similar to that at the base of an infant car seat in a rear-facing position in the back of a small family car.

The study revealed that this combination of movement and an upright position of 40 degrees (as opposed to lying flat) significantly increased heart and respiratory rates, and decreased oxygen saturation, leading to an “increase in potentially clinically significant oxygen desaturations.” In short, your baby can't breathe as efficiently when they're in a car seat.

Of course the experts aren’t saying we should ditch car seats, but the important factor here once again is time. They warn against keeping babies in a car seat for long periods, especially while sleeping.

“Parents should not stop using car safety seats to transport their infants. Infants must be protected in moving vehicles, and UK law requires car seats be used whenever infants travel in cars,” says consultant Paediatrician of the Great Western Hospitals NHS Foundation Trust, Dr Renu Arya.

“However, our findings support the AAP (American Academy of Paediatrics) guideline that infant car seats should not be used as a routine infant sleep environment.”

Although this research sounds worrying, it's important not to get over-anxious about your baby sitting in a car seat as part of day-to-day life. The key message is that car seats are for travelling and cribs and cots are for sleeping.

So, how long can my baby be in a car seat for?

What is the 2 hour 'rule'?

The '2 hour rule' is the established safety recommendation endorsed by safety experts and manufacturers. As you'd expect, this rule suggests that babies shouldn't sit in a car seat for more than 2 hours at a time. This applies whether your baby is in a car or out of it – even if the seat is being used as part of a pushchair travel system (pictured above).

The reason, as we explained above, is that babies and very young children can experience breathing problems if placed in a seated or scrunched position for too long.

“Car seats are desperately important to save lives from car accidents. However, families should not leave babies in car seats for long periods or once they are removed from the car,” explains Justin Daniels from the Lullaby Trust.

“Small babies do not have the ability to support their heads and this study shows being upright in a seat is a risky position for a long period of time.”

If you need to go on a longer car journey, try to stop every 2 hours for a break and take them out of their car seat for a break – younger babies will need a feed or nappy change every couple of hours anyway, so try to work time for a decent break into all longer journeys. Take a mat and give your baby a little time to lie and wriggle around in a new position on each of these breaks.

Those choosing to use a travel system with a car seat should consider it a convenience for short trips, or for moving the child from the car to the home. A car seat clipped onto a pushchair chassis is not a replacement for a carrycot, particularly if you plan to have your baby in their pram/pushchair for naps or very long walks.

It's always best if young babies are on a firm, flat, waterproof mattress in a separate cot, carrycot or Moses basket for at least the first 6 months of their life. This is because your baby’s ability to keep their head held up is not fully developed, meaning their head can flop down and restrict the airways.

Does it affect newborns differently?

Reports in mainstream media / social media have questioned whether newborn babies are safe if they sit in a car seat for as little as 30 minutes.

The research (2016), commissioned by the Lullaby Trust found that when newborn or premature babies sat in a car seat for 30 minutes, their heart and breathing rate increased, and their blood oxygen levels were lower compared with lying flat in a cot.

This happened when the babies were both stationary in the car seat and 'moving' in a car simulator, and these effects were more marked with premature babies but still seen with term babies.

It is recommended that if you use a car seat in the first 4 weeks of your baby's life, avoid using it for longer than 30 minutes. This includes using it in the car or as a combined period of time as part of a travel system.

What about lie-flat car seats?

Over the last few years, a number of car seat manufacturers have developed lie-flat or near-lie-flat car seats, which keep a baby in a much more natural sleeping position, while still being tested against the required car seat regulations. These products allow your baby to sleep in a more optimal position in some circumstances, providing reassurance.

There are two different types of lie-flat car seats available:

An infant carrier that has a lie-flat position — This is an infant car seat with a built-in recline. Popular models include the Cybex Cloud T and the Maxi-Cosi Pebble 360 Pro. These generally keep your baby upright in the car and can then be converted to a lie-flat position when the seat is placed on a travel system. The Pebble 360 Pro can recline into a fully lie-flat position in all modes, including in the car or on a pushchair.

Carrycot car seats — Models such as the Joie Calmi, Maxi-Cosi Jade or the Nuna Cari Next resemble a carrycot but have a built-in harness, and allow your baby to lie flat in the car. These seats are clicked onto a fitted base in your car, and the baby lies parallel to the back seat of the car, rather than facing the rear of the car. These carrycots can then be transferred onto a travel system without the need to move your baby after 2 hours.

These new models offer more flexibility and may mean you don't need to buy a separate car seat and carrycot, depending on your specific circumstances. Do bear in mind that the carrycot car seats in particular take up a lot of space in the back of your car, and not all reclining infant carriers can recline in the vehicle. They also all have harnesses that you won't find in a traditional carrycot.

Read: Why your newborn needs a lie-flat buggy

General safe sleep advice

• Always place babies on their backs to sleep
• Place your baby to sleep in a separate cot or Moses basket in the same room as you for the first 6 months
• Use a firm, flat, waterproof mattress in good condition
• Remove all pillows, soft bedding, cot bumpers and soft toys from the cot/crib
• Don’t let your baby get too hot
• Don’t cover your baby’s face or head while sleeping or use loose bedding

We've got more on safety here…

• 8 common car seat safety mistakes
• Car seats on holiday: how the rules differ
• Changes to car seat laws in 2023: what you need to know
• The safe way to lift and carry an infant car seat

References

^{1. Hazards Associated with Sitting and Carrying Devices for Children Two Years and Younger Batra, E. K. et al. The Journal of Pediatrics, 27/04/2015;167(1):183-187.}

^{2. Is the infant car seat challenge useful? A pilot study in a simulated moving vehicle. Arya, R et al. , 2019;33(3):257-266. Archives of Disease in Childhood - Fetal and Neonatal Edition, 2017;102:F136-F141.}

^{3. Apparently life threatening events in infant car safety seats. Tonkin, S. L. et al. British Medical Journal, 2006;333:1205}

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