1,2, and 3 are under exposed making some of the whites look gray. Bring them up about 1/3 to one half stop and they pop a lot more.
The alst one, I dunno. Maybe you are trying to show too much when the shot should be about the mom to be only, the surroundings are competing for my attention. It is also slightly tilted, the column behind her should have a lean the opposite direction you have it due to the way it's designed with a taper.
I feel that in the first one and the third one, the sister(s) look sort of awkward or uncomfortable, or maybe the shot was taken before they were settled in. Hands and stance on the first one, eyes and smile on the third
My favorite is the fourth one. I feel that it is the most maternityish and I love the location. The others are cute, but need some work. I think the others here have already provided some great CC on them, so I will leave that alone. I did my first maternity session not too long ago, I loved it! Very fun.
In my opinion the black an white one is the best..... but....
In all the color pictures, the only readon i know your pregnant is because your title says so.
In the black an white one you look pregnant but the pose is uninteresting.
What does it mean to be pregnant? How can you show pregnancy besides hands touching a belly...
Maybe mess with sillouettes, a series of photos to show your progression or maybe even experiment with some risque poses...
Your pregnancy could be a source of many photographic opportunities.... don't blow them on snapshots only.
I'm not trying to be mean spirited, only offering suggestions.