I often find I have to remind myself when photographing small infants, that they can't smile yet, and they aren't able to hold themselves in a pose. In portrait photography I get accustomed to creating a rapport with the subject so they will trust me in guiding them to a pleasing position and image. Unable to see themselves, subjects rely on the photographer to instruct them to an emotion provoking pose so the image will make a connection to the viewer. Infants of course, do not need guidance to a pleasing pose, they captivate and make emotional links to viewers naturally.
Infants remind me to look for the subject's natural way to connect with the viewer. If I wait for eye contact, good posture, and a big smile in an infant I will miss many powerful and lovely moments. Worse yet, the moment I will end up catching will look forced and most-likely caused by a need to belch. Instead, a drool soaked chin and a face buried in a teddy bear are the beautiful moments for the subject.