"Both mother and baby are healthy and doing well," Bilson's rep shared, according to People.
This is the first child for the couple, who met on the set of "Jumper" and started dating in 2008. Bilson is currently the star of "The Hart of Dixie," but she's best known for her role as Summer Roberts on "The O.C." Christensen is best known for his role as Anakin Skywalker/Darth Vader from the "Star Wars" prequels.
The couple also support the No Kids Policy, which believes celebrity kids should not be photographed without consent from the parents. Kristen Bell and Dax Shepherd, Jennifer Garner, and Halle Berry are among the policy's strongest supporters.
In a May 2013 Cosmopolitan interview, Bilson shared, "I definitely have family on the brain. Having kids is something I want to see in my future – I hope." A year later in May, Bilson's pregnancy was revealed.
Congratulations to the young couple!