Laura Prepon

Laura Prepon

Ashton Kutcher and Mila Kunis' former co-star thinks it's "so awesome" that they're expecting their first child.

Laura Prepon, who starred with the couple on 'That 70s' show for nine years until 2006, can't wait for them to welcome their first child, rumoured to be a baby girl, later this year.

The 'Orange Is the New Black' star told UsMagazine.com: "It's going to be great."

The 34-year-old actress previously revealed she is still very close to all of her former co-stars as they "grew up together" and would love to be a bridesmaid at Ashton and Mila's upcoming wedding.

She said: "Of course I will [be there]. Are you kidding? All of us are going to be right up there on the altar."

The actress also said she "wasn't surprised" when the couple, who got engaged a few months ago, started dating in 2012 following his split from ex-wife Demi Moore in 2011 because the 30-year-old actress shared her first ever kiss with the 36-year-old actor when she was a teenager.

Asked about their romance in the past, Laura, who was recently linked to Tom Cruise, said: "It's incredible. I wasn't surprised either."