On facebook

If you want to make one global announcement of your pregnancy, there is hardly anything better than a facebook update.

You could update your status, saying for instance :
"I love x (father's name) the most because I have two heart that are beating for him!"
"No alcohol for me from now on - for some time at least ;-)"
"Pregnant!"

Another original way, is just to post on facebook: "delivery expected in 6 months!"