Ashton Kutcher and Demi MooreAshton Kutcher has revealed he and wife Demi Moore are letting “nature run its course” when it comes to expanding their family.

The What Happens in Vegas star is already step-dad to Demi’s three daughters from her marriage to Bruce Willis but the pair have been dogged by pregnancy rumours since they married in 2005.

But Ashton said recently they’re not particularly trying for a baby right now: “I think some day we would really like to have children, it’s about nature running its course.

“I don’t know about right now because I’m really busy working.

“And Demi’s going to Pennsylvania to start a film so I think it would be hard to balance all of that right now with having kids.”

He added: “I have thought about adopting a kid my whole life. When I was eight I had a friend called Terry and one day he told me he was adopted.

“He said his parents told him there was a more special bond between them because they picked him. I thought that was pretty profound and I would be open to the idea. In a way I’ve sort of had that gift and opportunity with our girls.”