I've had to go through that... When my ex and I were both 19 we found out we were pregnant...
I approached my mom early on (I lived with her, kinda had no choice) and told her straight out with my (now ex) oddly by my side (reason why I say oddly is because my mom's one of thsoe nut-cracker type of moms - all anti-male and all...) ... she instantly reacted the way i did not expect, she smiled and called my sister instantly spreading the 'good' news... With my dad (Parents aren't together) I waited till I was past the 'miscarriage' period then told him i beleive over the phone and he got upset... not because I was pregnant, but because I Waited so long to tell him. I now regret not telling him sooner. As for my ex's parents, they wern't so nice about the whole thing, they gave him an ultimatum - me and the baby, or them! He chose us... untill his mistress came along when our daughter was 6 months old (but that's a whole other post/story) .. so, my advice..
Tell your parents, let them know how you feel - don't hold it in because it puts more stress on you and the longer you wait the more your parents will 'freak out' if they'll even freak out in the first place... Just sit them down and say it.. that's what I did. I took a deep breath and just said \"Mom, I'm pregnant\" and the conversation just went from there.
Now my daughter is 5, and all is well. (Even the ex's parents ended up comming around about 6 months into the pregnancy.. util my ex and i split, then it became a COMPLETELY different story ... they tried to take her.. but again, a whole different post.. lol)
I hope this helps.. Keep us posted and good luck!... oh and
CONGRAGULATIONS!!!!!