I understand that it's now OK to do this - apparently having the kid on a leash/harness means they "can explore their world with both hands" rather than going through life with one hand raised up above their head in their mother's grasp. Apparently the leash/harness is good for brain development and posture. I'm from the first generation where such harnesses were not OK (the Dr Spock baby in person), and I sorta kinda get where they're coming from. Also a less stressed mum.