Newborns generally hold the adorable curled up position known as the "newborn scrunch" for a few weeks. It's one of the reasons I like to photograph them as close to their birth date as possible. The other reason is that younger newborns are sleepier and therefore easier to pose.

You may being asking yourself, why does she prefer to photograph sleeping newborns? The reason is simple. It's because their eyes are still developing and they have limited focus distance and light sensitivity. As your baby is learning to use both eyes together their eyes may also appear to wander or cross. 

I much prefer to wait until they are at 3-4 months when they can focus on faces and I can hopefully get a smile.