“Babies should be placed flat for sleep whenever possible, and keeping babies in car seats or other devices for long periods is potentially unsafe for babies in the first few weeks after birth. There is no good evidence on the age at which putting babies in an inclined or sitting position for long periods becomes safe, but our advice to parents generally is that babies should not be left in such positions for more than is absolutely necessary for at least the first 6 months.
There is currently no good evidence-based advice on how slings should be used. There is a potential problem using a sling for a long period when the adult is in a sitting position – especially when they have limited ability to move or change position as may occur on a crowded train or bus. The RoSPA “TICKS” advice for using slings is a very sensible first attempt to ensure slings are used safely. The manufacturers do not have any direct evidence on how to ensure slings are safe and it seems fair to me that as they make a significant profit from selling these devices they should contribute to the work trying to make them safe. Currently there is no enforceable national standard to which manufacturers of slings or other baby carriers are required to comply.
For families on trains, it is very important that they have the ability to place their young infant in a safe horizontal position for sleep on longer journeys. I cannot at present give a precise definition of a longer journey, but this should certainly include all journeys lasting more than 30 minutes for very young infants (less than a month) and probably more than an hour for older infants up to 6 months of age. These figures are not based on direct physiological measurements but on observations of infants in the community and the laboratory.”
Professor Peter Fleming
Professor of Infant Health and Developmental Physiology
University of Bristol.