Spring, when I had L nearly 9 yrs ago, they always put him on his side to sleep - and you would use the other side for the next sleep. 20mths later when I had E the 'recommendation' was for back sleeping. Now when I asked about this they said it was because on their back their airway was kept clear and if they possetted it would go past their windpipe and go straight down the back of their throat, bypassing a choking episode with the airway being blocked off. Whereas on their side there is a minute risk of choking on their vomit. Now personally I think that if you have a bubs who sleeps better on their side than on their back then you should do that so long as it is within your comfort zone. I really couldn't see how that much could have changed in that 20mths between my 2 being born and I always just slept them in the position they were most comfortable in.