The first few weeks with baby can be grueling. Here you are, waking round the clock, using every last molecule of energy taking care of someone you just met, who’s completely helpless (and incapable of saying “thank you” -- just yet). Your worth-the-wait reward for getting through? Baby’s first smile. But don’t expect those first gummy grins too soon. Your baby’s brain needs a few weeks to develop before he’s able to smile at you for real. Looking forward to that or wondering whether it’s already happened? Here’s everything you want to know.