While there's no word yet on the sex of the baby Ryan Gosling and Eva Mendes are expecting this October, a source tells PEOPLE the couple are over the moon with happiness.
"They literally could not be more excited," says the source. "She's feeling great."
This will be the first child for Gosling, 33, and Mendes, 40, who began dating in 2011 and, the following year, played parents in the dramatic film The Place Beyond the Pines.
The pregnancy wasn't necessarily surprising to the actor's friends. "Ryan adores kids. He has such a way with them," an insider told PEOPLE last year. "He loves being around kids and can't wait to be a dad."
So, what makes Gosling and Mendes click?
"She's very friendly and approachable. She's also very independent and Ryan is too," the insider adds. "He loves that Eva isn't prissy. She's like a dude. She's outgoing and makes everyone feel great."
The couple most recently worked together on Gosling’s directorial debut, Lost River, which premiered at this year's Cannes Film Festival.
Reporting by JENNIFER GARCIA and AILI NAHAS