Help!!! Please

I know this might be stupid but I need help on telling my parents I'm pregnant. I know I'm 21 pay my own bills, live on my own, and in a great relationship, but I don't wanna disappoint them. Growing up in a home where you don't have sex before marriage its going to be hard for me to find the right way to do it. Any advise would be very much appreciated! Thank you in advance.