Fergie, 38, gave birth to Axl at
She and Duhamel, 40, announced the pregnancy back in February via an
"Josh & Me & BABY makes three!!! #mylovelybabybump," she captioned a photo of a cat and two kids who appeared to be the parents-to-be as babies, Photoshopped together.
This is the first child for the couple, who married in 2009.
Duhamel told The Times last March that prepping to be a dad was "exciting."
"I hear all my friends telling me about how fantastic it is and all the things that go along with being pregnant and the stages of it all. But until you're actually going through it you can't even relate," he said at the time.
"Right now, we're just fascinated by the whole idea there's a baby growing inside of her," Duhamel added. "We're fascinated by every stage of its development at this point. We're already feeling a real connection to it. This is what I was meant to do, and we're both really, really excited about the whole thing.
"He's going to be an amazing father," Fergie told People in April. "He's got natural parenting instincts."
In July, the "Transformers" star appeared on "Live! With Kelly and Michael" where he spilled the beans that they were having a baby boy by choosing a blue onesie during a game with the daytime show's hosts.
This month, Fergie officially changed her name from Stacy Ann Ferguson to Fergie Duhamel, making one surname for their new family.
Earlier this week, the two showed off their last-minute preparations with "The Dog Whisperer" star Cesar Millan.
"@joshduhamel & I getting our doggie daughter ready for her new brother with @cesarsway," Fergie captioned a photo of herself with Duhamel, Millan and their dog Zoe.
Looks as if their home is going to be a safe haven, indeed. Congrats!
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