My favorite time frame to pose and photograph a newborn is between 5-21 days old. In those initial days, babies can be a bit touchy, constantly searching for food. Although they are very sleepy, they aren't as deeply asleep as they might be a few days later. Sometimes, the mother's milk hasn't come in yet, or the baby is still adjusting to life outside the womb, and the mother might also need a few days to recover. I try to avoid the growth spurt period from 9-12 days as they cluster feed during that period. Babies older than 21 days can still be posed and photographed, but they tend to become more aware and alert. They might not be as flexible for those womb-like poses as they are earlier, but with an experienced newborn photographer, you can definitely get those beautiful portraits. The oldest baby I've photographed for a "newborn session" was 7 weeks old, and he did all the poses, which is called a unicorn baby. This little one is 23 days old and did wonderfully! We did have some awake periods, and I could feel while posing him that he was starting to lose that newborn scrunch, but we still accomplished everything.