I'm sorry but these aren't doing it for me. The depth of feild is nice with that 1.8 aperture, but 1 and 3 are underexposed, the babies face is cut off in 1 and there is some major blur in the corner of 2 which is distracting. but on the upside on number 2 the eyes are are amazingly clear and catches your eye. With a 50mm you need to be careful inside so you don't start cutting off stuff. I would just look at some other baby pictures on the internet and mess around with the composition. you just need a little bit more practice and you will start getting some good shots.
what's great with a f/1.8 is that you can have a fast shutter speed so you can get a good picture even when the baby is moving. My advice is to just step back, pay attention to the rule of thirds and take a ton of pictures. If you need to crop you can do that later. Good first attempt though