Pet Issues?

Anyone have a pet that experienced jealousy through their pregnancy? I have two cats, both a year apart. One of them has always been affectionate and she doesn't seem bothered by my pregnancy. My other cat, the more "outgoing" cat seems to sense my pregnancy. When I show my stomach, which I'm not even showing, or touch it, she gets defensive and wants to attack or stares me down. Anyone experience anything similar? I'm not sure what to do if it worsens.