1. Toss this one. There are too many issues with it. The black and white is grayscale. Black and white is very hard and should be black, white and everything in between. Never place your subject directly on top of a background like that. The harsh shadows it creates is pretty bad. Using your on-board flash directly for a portrait is never going to produce a flattering image.
Baby bump images need to show the bump, not the broad side of mom making her look just wide. Be very aware of how the body is posed and profiles are usually your best bet.
2 is a lovely silhouette. She's well placed in the composition.
3. I am kind of lost, but the leading lines are nice!
4.You have a nice exposure, you've stopped the action, but you've got some major composition issues there.