One of my favorite things to do when posing newborns is to use the parents' hands.
Now I use the word "pose" loosely as I do very minimal, newborn led posing.
But I do like to get some shots of the baby alone on the bed, awake or asleep, if the baby is okay with it.
Simply ask the parents to come and hold the baby firmly in the position you desire. This allows you to capture the newborn with their parents loving hands on the baby, which is a beautiful shot, then allows you to capture the newborn alone. The baby is usually very calm after he or she has just been comforted by familiar hands.
Try it out next time you photograph a newborn. Let me know how it goes.