In theory, babies can be placed in a carrier as a newborn, assuming they are at least 7 pounds. So day one works in many cases! "Any caregiver may carry the baby so long as the parents are ok with that, of course," said McNeilly. "The sooner a caregiver starts wearing the baby, the better for both. Babywearing is a weight-bearing exercise, and as the baby grows, so will the wearers' strength. Win-win."