I think white furry or white shear fabrics, or other light-colored furs, throws, or blankets look more infant-like than black does. Black seems rather severe, and the infant does sort of seem to "float" in the blackness, with no real visual anchor point. Your skin tones on the first two look very realistic to me, while the third one's a bit hot on the back.
cgipson1 brought up what he referred to as DOF issues in #1...I dunno....yes, the feet are out of focus, but that doesn't bother me a whole lot. But some people really do not like that wide-aperture look on baby portraits, and like to see all parts of the body in sharp focus. So, I suppose that could go either way.