Duhamel, 40, and Fergie, 38, welcomed their son in August and the actor insists the The Black Eyed Peas singer is very happy to be a mother, reported People magazine.
"She is doing so great. She really is. She is happy. She looks amazing... Three weeks ago she gave birth and she looks probably better than she did before," Duhamel said.
"I don't know if it's because of what she's been eating or what, she looks really, really great," he added.
The couple cannot stop staring at their new born son.
"There's something you can't really describe until you go through it. I think any parents out there would understand that... It's just an incredible time for both of us," he added.