I don't think she's pregnant, so much as she was using her hand to emphasize the part about being a woman by gesturing at her internal plumbing. Now if she was making a habit of slowly rubbing her stomach in circles, as pregnant women tend to do, then I'd be leaning much more towards her being with child...no pun intended.
Kanzaki still seems too mysterious to be just a hot guy. I suspect his intentions towards Mai go much farther than just a high school romance thing. He's a little toooo cool to be your average cucumber.
