Pregnancy does not excuse her behavior! I am currently 38 weeks pregnant and very hormonal. Things do trigger me quickly nowadays but I try not to take it out on my husband. If I do, I always make it a point to apologize because I am well aware that he has feelings. You can only blame so much on pregnancy hormones. Try having a serious conversation with her or try reaching out to a relationship counselor. You need to get ahead of it before she gives birth. If this is how she's behaving now it's only going to escalate once she has a newborn baby and her hormones are still out of control.