Dax Shepard and his mother during "Employee of the Month" in Los Angeles. Credit: Mirek Towski/FilmMagic

Hours after Kristen Bell's rep confirmed her pregnancy to Us Weekly, the actress' fiance, Dax Shepard, opened up about their happy news on The Tonight Show With Jay Leno Nov. 5.

"It's true," the Parenthood star said. "My mom is probably the most excited. It's an unhealthy thing -- I don't recommend it -- but she has a Google alert on my name, so if I do anything, she finds out about it, basically."

This will be the first child for Bell, 32, and Shepard, 37, who began dating in 2007 and have been engaged for nearly three years. The timing was right for the Hit and Run costars to start a family, multiple sources tell Us. "She and Dax are so cute and in love. They are the real deal," an insider says. "They laugh all the time. He is so respectful to her. . .chivalry isn't dead for him. He opens doors and takes care of her."

A second source agrees that the When in Rome costars "are the cutest couple" in Hollywood. "They are so in love and completely committed to each other, no question. One of those relationships you're jealous of."

Even with a baby one the way, Shepard and Bell will not tie the knot until same-sex marriage is legal in California. "We wouldn't want to invite all of our friends who don't have that right to celebrate us, who have that right," Shepard said on The View in July. "We just don't feel right about that."

Having kids before marriage "doesn't really bother us," Veronica Mars alum Bell said in an August Larry King Now interview .