Also the grasping reflex: if you place your finger in the palm of a newborn's hand, she will grasp it. It works almost without fail with any newborn baby. After a few months it completely disappears: grasping is no longer a reflex but a voluntary act, and as often as not she won't be inclined to do it.

I read that both failure to demonstrate these reflexes while newborn, as well as continued existence past a few months old, are signs that something might not be entirely right with the baby.