Justin Bartha is to become a father for the first time.

'The Hangover' star married fitness instructor Lia Smith in Hawaii on Saturday (04.01.14), and friends have now confirmed she is pregnant with their first child.

A source told UsMagazine.com Lia ''had her hand on her stomach most of the time'' and ''looked like she had a little bump'' under her white gown at the ceremony, held at a historic fishing pond on the island of Oahu.

Later at the reception, held at the nearby Kualoa Ranch, Lia donned a loose-fitting dress and was seen touching her stomach as she walked around.

Among guests at the low-key wedding were Jesse Eisenberg, Reese Witherspoon and her husband, Jim Toth - who is Justin's agent - and his 'The Hangover' co-star Ken Jeong.

Justin, 35, and Lia, who hails from Hawaii, were first linked in January last year when they celebrated the start of 2013 together on a Maui beach.

The actor then proposed in May when they made a romantic trip to Big Sur, California.

An insider said at the time: ''The trip to Big Sur, the engagement, the ring, everything. So cute.''