How to deal with this problem

Amanda

I'm currently 35 weeks pregnant with my second child. My first is almost 5. She loves her sibling and is very excited to be a big sister but this thing has been happening a few times and it's starting to concern me a little bit. It's happened 3 times already and I'm not sure how else to handle it before it gets worse. So the situation, today she was running around and screaming and I asked her not to scream while running around because the one dog we have gets upset at the loud sounds and I didn't want him to go after her or anything crazy(he's a little terrier so not dangerous just loud and barks alot) and she got upset with me and tried to push on/hit my stomach really hard. Similar situations before where she got mad at me and tried hurting my stomach. Today I put her in timeout and we had a long talk after about how that's not okay to behave that way. I told her if it happens again she will be in way more trouble and not happy about it but I want the problem to be fixed sooner rather than later because I'd be so upset if she hurt her brother after he was born because she was mad at me for something. We never had this problem before, it started a couple months ago. Any advice would be helpful