I did a very quick Google search. the following is from The Nappy lady site: https://www.thenappylady.co.uk/2929adva ... appies.asp
'Some paediatric specialists in the USA believe that the increase in hip dysplasia and other spinal injuries is related to the lack of padding and support provided by disposables – which is getting worse and worse, as they get ever slimmer in design, and fuller in chemicals. Bear in mind that most toddlers will fall repeatedly on their bottom as they learn to walk, and the extra padding provided by real nappies can soften the blow considerably.
In Europe, the use of additional padding is accepted practice in paediatric hospitals as a method for managing hip displacement in newborns. According to J A Wilkinson (Proc R Soc Med 1975 Aug;68(8):476-9), “[For] those babies in whom the capsule of the hip-joint is mechanically stretched: Spontaneous reduction and recovery is high in this group, if the babies are nursed in the prone posture with double nappies.” Of course, in much of Europe these days, that additional padding is now disposable, but cloth nappies by their nature provide similar benefits from the start for all children.'