I just don't think they're natural. Babies don't look like they're in a natural posture when they're in them, obviously, because they're not able to walk yet, so I think that in terms of development it's probably not right.

I was one of those babies that went bottoms up, at 8 months old. Followed Mum out to the letterbox, she forgot about the step. But I'm OK! And I walk fairly well now, but I do have terrible posture... who can say though?