Why am I having dirty dreams all of a sudden?

Im 33 weeks pregnant (not sure if this has anything to do with it) but for about a week now every single night I have some sort of sex dream and wake up in the middle of an orgasm, but my bf said that I hadnt been moving or moaning, ita very strange because apart from this last week iv never had dreams like that in my life and never knew a dream could bring me to orgasm in real life!! im not complaining haha but its jist very strange..