"It's a fairly traditional name but you don't hear it very often. It means a lot to both of us and part of it is a family name," the 40-year-old star admitted.
"We're not telling anybody because we don't want to hear it. No matter what you choose, people are going to have their comments."
Fergie, 38, has been glowing throughout her pregnancy and hasn't suffered from many of the symptoms other pregnant women have to deal with.
She is so comfortable in fact, that the couple are already thinking about having another.
"The girl is so impressive," Duhamel said.
"You never know how it's going to go. Some girls have a tougher time, some a little easier. Because it's a boy, it's been a really lucky pregnancy in a lot of ways. She's been happy, in good spirits, she looks great.
"Even at eight and three quarter months, she's still in great spirits and looking beautiful. And that just means that she's going to want another one, which is good for me."
- Cover Media