Ryan Gosling and Eva Mendes
Ryan Gosling and Eva Mendes are expecting a child together.REUTERS

Ryan Gosling, who is expecting his first child with Eva Mendes, is running errands and cooking meals for his pregnant girlfriend, donning the role of a perfect father-to-be.

The Hitch beauty has "barely left the house" since she found out she is pregnant, to keep the news under wraps, the Us weekly reported.

A source said the couple's lives completely changed after the pregnancy. They used to travel all over the place together and go on hikes with their dogs, but now they are barely seen outside.

"Ryan goes out and gets the groceries. Eva's been wanting pasta, and he's cooking her meals. Ryan has already stepped into the role of caring father-to-be," the report says.

The 40-year-old actress, who is set to give birth in October, has reportedly decided to start a family with her heartthrob because she knew how much the Gangster Squad star wanted to experience fatherhood.

"This has been a long time coming. Ryan and Eva definitely discussed children before. She knows how much he wants to be a dad and he's going to be an amazing father," a source said, according to People magazine,

"Eva just hasn't ever wanted anyone beyond her close friends and family knowing more than they had to. And Ryan is certainly private and always has been."

The 33-year-old actor, who met Eva on the set of Place Beyond The Pines in 2011, has always been open about his desire to start a family.

Ryan previously said: "I'd like to be making babies but I'm not, so I'm making movies."

"When someone comes along, I don't think I'll be able to do both and I'm fine with that. I'll make movies until I make babies," the actor added.

The stunning brunette is rumoured to be around seven months pregnant. She was photographed wearing a baggy dress and hiding her baby bump with a bag while walking to her car in Los Angeles last week.