Aside from the obvious lighting issues, there are some DOF problems as well. in #1 and #3 the babys arms are OOF and the rest looks soft to me.
natural light is great....provided you are getting great lighting with it. I am a HUGE fan of OCF and bounced flash.
#2 has some very harsh light from somewhere, and also could have greatly benefited from some fill flash.
I don't know what aperture you shot these at, but if I had to hazard a guess, I would say f/1.8-ish. I would stop the lens down a bit and use a flash.
#2 is the strongest of the set as far as technical aspects go, as well as composure.