AceShowbiz -

It's official, Kristen Bell is having a bun in the oven. It's just revealed that the "Veronica Mars" leading lady is due to give birth to her first child in late spring 2013. The baby will be her first kid with her actor fiance Dax Shepard.

"They're so excited - they're both ecstatic. They can't wait to become parents," a friend tells PEOPLE. "Kristen had a little bit of morning sickness early on but she just started shooting the second season of 'House of Lies' and is feeling great now."

Kristen and Dax have been engaged since 2009. The "Parenthood" actor popped the question to the "Heroes" beauty three years after they started dating. The couple has shared screen in such movies as "When in Rome" and "Hit and Run".

The betrothed couple won't get marry until same-sex marriage is legalized in their home state of California. Of having children before marriage, 32-year-old Kristen told Larry King earlier this year that it "doesn't really bother" her and 37-year-old Dax.

"We wouldn't want to invite all of our friends who don't have that right to celebrate us, who have that right. We just don't feel right about that," Dax explained on "The View" last summer. Kristen chimed in, "Can you think about how rude that would feel?"