Cause of regurgitation in two valves?

I have slight regurgitation in my mitral and tricuspid valves. I'm 23 and just found out at 34 weeks pregnant. My question is, how do I find the cause of this? I've read causes on the Internet and none of them sound familiar. I've heard of rheumatic fever but my mom said I have never had it. I don't know of anyone in my family with heart issues? Thanks in advance