"It's definitely part of the plan," Duhamel says of parenthood.
"We just need to be in the same city. It's just a matter of, like I said, when."
The 37-year-old actor, who tied the knot with the Black Eyed Peas singer in 2009, revealed they were thinking about a small brood.
"I just want a healthy, happy, little baby. That's it. I would like to have a boy and a girl ultimately, but I'll take whatever," he told Entertainment Tonight.