Bill and Giuliana Rancic
Andrew Eccles/The Style Network
06/18/2012 at 09:00 AM EDT
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.
About 100 people, including Lisa Ling, Melissa Rivers and George Katsopolis, helped the couple celebrate at the shower, planned by Mindy Weiss and hosted by Giuliana's manager Pamela Kohl and best friend Colet Abedi.
"Such a blast!" Tweeted
the E! News
host, who was diagnosed with breast cancer
Younger guests crafted, swam, played in a bounce house, as a camera crew filmed the gathering for the couple's reality show Giuliana & Bill
. Another party activity: a make-your-own perfume bar.
And it looks like the little Rancic is one lucky guy. Among the gifts: three strollers, including a 4moms Origami, and a bassinet. (The couple, who announced in April that they would welcome a baby
via a gestational surrogate, also registered for plenty of monkey-themed goods from Bel-Bambini boutique.)
But no one left empty-handed. Guests were treated to gift bags with Tory Burch sandals, Mabel's Labels Bag Tags, Playskool Poppin' Park and a Kai candle.