Orgasms while sleeping

I've been having an orgasm while sleeping at least once a week since around 18 weeks. I don't touch myself, and my husband is usually already at work. I wake up while having an orgasm. I'm usually having an orgasm in my dream as well, and it actually happens in real life. This has never happened to me before in my whole life until this pregnancy. Has this happened to anyone else? Just worried that it's not normal.