Talking To Parents About Birth Control

My parents and I have always been open, but we never had any sort of talk about sex. I learned everything I needed to know from school, but as my long time boyfriend and I get closer and closer to feeling comfortable having sex, I wonder how to go about speaking with my mom about getting birth control. I would need them for insurance and health care purposes, but if I had it my way, it wouldn't be their business. Help!