The couple have previously spoken out about their desire to start a family, and the Black Eyed Peas star admitted she will be overjoyed when she does fall pregnant.
Fergie told the American edition of OK!: "It's definitely something that we're interested in doing. We made no secret of that. We'll be very excited when it happens."
Duhamel has previously said that the couple are planning to start their family first rather than adopting another pet to replace their rescue dog Meatloaf, who died from a brain disorder.
"I think we're going to focus on our human baby first," he explained. "Hopefully we'll have kids, and then at some point we'll get another dog.
"I don't know how to describe it, but anyone who would come over, they all went to Meatloaf."
Watch the music video for Fergie's 'Big Girls Don't Cry' below: