Though your new baby isn't as breakable as a china doll, he's most vulnerable in his first four months. His head's bigger than his body, and his neck muscles aren't strong enough to stabilize it, says Carol Berkowitz, M.D., president of the American Academy of Pediatrics. Also, his brain is still forming myelin -- cells that give it solidity.
That's why just two or three rapid jerking motions while holding a baby can be harmful. Each year, more than a thousand infants in the U.S. die or are seriously injured from "shaken baby syndrome." A newborn's bones are also more delicate, so squeezing too tightly (sometimes done inadvertently in frustration) can cause fractures.
By the time a baby's 5 or 6 months old, his neck should be strong enough to hold up his head, and he's less vulnerable. Until then, anyone who takes care of him should know how to hold him: Support the head a little higher than his body, with the crook of your elbow or hand. And if any caregiver ever feels on edge when a baby's crying, make sure he or she puts the baby safely in his crib, leaves the room to regain composure, and gets help.