Car Seat Breathing

Research History & Advice

Details of the research over the decades + more

This page could be many tens of thousands of words long but the problem would be you would not have the time to read it all. So, we are just mentioning the key medical research reports over the last three decades and in the "Links" page we are providing links to other websites so you can do more research should you wish.

In the early 1990's it was discovered that when a newborn is secured in a semi upright sitting device such as a child's car seat that this can affect their breathing and blood oxygen levels. 

The reason is straightforward. A newborns airway is the thickness of a drinking straw and the lungs are the last organ in their body to develop prior to birth. By placing a newborn in a semi upright car seat the head can flop forward causing less air to reach the lungs.

Additional factors are when sat in a car seat other organs can press against the undeveloped lungs making them even less efficient. Being secured with tight fitting straps (and they must be tight in event of an accident) makes things even worse.

In fact on average, a newborns lungs are not very efficient until some months after birth but in time (probably about four to six months, but no one knows for certain how long) baby outgrows this issue called car seat oxygen desaturation or in other words the lowering of blood oxygen levels when secured in a car seat.

A low blood oxygen level is serious and can cause lots of different medical problems including brain damage and even death.

Because of the mounting number of medical research reports the American Academy of Paediatrics (APP) in the early 1990’s devised a test called the "Car Seat Challenge". This test, measured a newborn babies blood oxygen level whilst sat in a car seat just prior to discharge from hospital and was initially given to premature and low birth weight babies only.  Because of the time, it takes to give this test, the Car Seat Challenge was not adopted by the vast majority of UK hospitals. In short newborns were packed into their car seat and discharged.

In 2001 there was a major change. American paediatrician Dr Jennifer Merchant and her team published ground breaking research based on 50 pre-term and 50 term healthy babies just ready for discharge from hospital.  She discovered that term babies suffered very similar lowering of blood oxygen levels when secured in a car seat to that of pre-term babies. In the UK, this research resulted in the unofficial "Two Hour Rule" but still the vast majority of UK hospitals never tested newborns with the Car Seat Challenge test…… nor told parents of Dr Merchants research.

A few years later a Japanese paediatrician (Hiroake Nagase) and his team published results comparing semi-upright child seats to the newer design lay flat seats and carrycots. Nagase proved that lay flat seats and carrycots did not lower blood oxygen levels to dangerous levels and at that point we knew for sure that angle was the primary problem. However, at that time there was one big problem with car carrycots in that some models did not do well in crash tests.

In essence, child car seat research came from America, New Zealand, Australia, Canada and Japan. A big debt is owed to the many dozens of paediatricians and researchers and in particular to Joel Bass (America) and Shirley Tonkin (New Zealand) who sadly recently passed away after decades of work highlighting the problems of  car seats in relation to Sudden Infant Death Syndrome (SIDS).

Jump forward to 2016 and the next big break through occurs. This research was done in the UK and one of the joint authors was Professor Peter Fleming OBE, a world authority on SIDS and to whom we have designated a page on this website.  This research entitled "Is the infant car seat challenge useful? A pilot study in a simulated moving vehicle" was co-authored with Paediatrician Dr Renu Arya based at Swindon's Great Western hospital and backed up by a team health professionals and scientists from Bristol & Southampton Universities. 

The research was funded by the Lullaby Trust (formerly the Foundation for The Study of Infant Deaths) and clearly they would not have funded high costing research without believing there were very good reasons to do so.

The Fleming/Arya research took Jennifer Merchants study several stages further. They used an equal boy/girl mix and an equal pre-term/term mix. All the babies used were healthy and ready for discharge from hospital.  This research was considered a "pilot study" because for the first time an actual journey was being added into the equation by way of vibration.  Nevertheless, this vibration was incredibly low key, simulating a moving car at 30 mph without taking corners and without acceleration.  It was later stated by one of the authors that the results, when adding normal driving conditions, are likely to make the results even more concerning than they were.

The protocol of the research was quite straightforward. Measurements were recorded regarding Heart Rate, Respiratory Rate, O2 Saturation, Total Number of Desaturations and Total Number of Desaturations <85% (which is a horrifically low figure and very concerning).   The baby’s positions were at rest, at 30 degrees in their own car seat, 40 degrees in the car and finally 40 degrees in the car in motion over a 30-minute period (though because of physiological distress some baby’s tests had to be stopped early).

It should be noted that many of the newborn car seats available (but not all) are angled at more than 50 degrees once in a normal car.

The results of this new reserach was very worrying and led to both Dr Arya appearing on BBC radio programmes and Professor Fleming appearing on BBC TV News warning parents about the risks. Their advice is:

Do not to take newborns on journeys in conventional semi up-right car seats for longer than 30 minutes for the first four weeks and then to gradually increase times as baby gets older.

Long trips should be avoided and where possible someone should sit alongside a newborn when using a car seat. If you must take a newborn on a long journey take very frequent breaks, ideally every 30 minutes or so. Do not place a conventional infant carrier car seat on a pushchair to make a travel system until baby reaches six months of age.

All the results from the Fleming/Ayra research showed significant statistical differences in every type of test but none more pronounced than the blood oxygen level tests details as shown on our "Graphs" page.   Full details of all the relevant research reports can be seen by going to our "Links" page.  


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