Justin Bartha and his wife Lia Smith have welcomed their first child, a baby girl, Us Weekly exclusively confirms. Credit: Michael Buckner/WireImage

Here's to their new normal! Justin Bartha's wife Lia Smith has given birth to the couple's first child, Us Weekly exclusively confirms.

The Hangover alum, 35, and Smith welcomed a baby girl on Sunday, April 13, a source adds to Us. The new mom went into labor Saturday night.

Bartha and the personal fitness trainer got engaged in May 2013, and tied the knot back in January in Oahu, Hawaii. During their intimate ceremony, the newylweds were feted by Reese Witherspoon, her husband Jim Toth (who is also Bartha's agent), Jesse Eisenberg, and his Hangover costar Ken Jeong.

"[She] had her hand on her stomach most of the time," an eyewitness told Us. "She looked like she had a little bump."

Indeed, following their nuptials, Us exclusively confirmed the new bride had a bun in the oven.

"They are an amazing couple," an insider said of Smith and Bartha, who dated Ashley Olsen from 2009 to 2011. "[They're] so gorgeous together."