Help.. I need to tell my parents I'm preggo

After 4-5 months, my boyfriend -now fiancee- and I are finally pregnant. Now I need your help.. my fiancee family already knows, they were hella excited. My siblings all know and they are all for us to have the baby; now my parents.. they are hella religious, they're moving to Costa Rica to become missionaries, and were very disappointed in my older brother for getting his one night stand pregnant (but he's happily married now to her with 2 kids, that I babysit Monday-Friday) and I'm scared to tell them. Yes I'm a 22 year old, I'm an adult now, have my own place, pay bills, the whole shabang. Now real question is how did you guys tell your parents?? I need ideas lol