"They've both talked about this for a while and are so excited," a Bilson insider tells Us. "Everyone is beyond thrilled for them."
Bilson's had babies on the brain for quite some time now. In an interview with Cosmopolitan back in May 2013, the "OC" alum gushed: "I definitely have family on the brain. Having kids is something I want to see in my future – I hope."
The actress is also bound to be an amazing mom given what a good girlfriend she is: "I'm a really good girlfriend -- I always put all that first in my life. I'm definitely the person who would make him his favorite dinner to come home to," she told the mag. And friends agree: "They will make wonderful, hands-on parents," a pal tells Us.
"Star Wars" actor Christensen, 33, and Bilson met in 2007 on the set of "Jumper." The typically private, low-key couple got engaged in December 2008 and then called it off in August 2010, only to reconcile three months later.