Ranting

My coworker and I share a mutual friend. Our friend had told her about me being pregnant which I'm not mad about. I haven't told work yet but she goes and gossips about me being pregnant. She never came to me and said anything to me, just skipped to the gossiping. I'm very annoyed because 1 It wasn't her place to say anything and 2 I wasn't ready to tell work. I found this out through a coworker I did tell, she was the only one I had told.