Giving Pregnancy Information?

So, I am looking at possibly taking a new job and have been in job negotiations for many months now. My co-worker who knows that I am pregnant told my future employer about my pregnancy. I haven't found a law stating that this guy telling my future employer is an illegal act, so I want to know...does anyone know if it is against the law for someone else to dilvulge your personal information like that? Or is it just plain rude and there's nothing you can do about it!?