updated 06/18/2012 AT 9:00 AM ET
•originally published 06/18/2012 AT 1:30 PM ET
It was a blue Father’s Day for Giuliana and Bill Rancic – literally.
Before officially announcing that they are expecting a boy, the couple broke the news in a very special way to guests at their baby shower Sunday afternoon.
Blue and pink balloons filled the room at the private home in a gated Beverly Hills community. The big reveal: Giuliana – in a yellow dress – and Bill released a set of blue balloons into the sky to the cheers of partygoers, a source tells PEOPLE.