Chris Noth is to be a father for the second time

Chris shared a photo of the 37-year-old actress standing in front of a sliding glass door, cradling her bump.

He joked in the caption: "Orion is getting a brother -- I better get my ass in shape."

Chris' 'Sex and the City' co-stars were among the first to congratulate him on the happy news.

Sarah Jessica Parker - who has three sons with her husband Matthew Broderick - wrote: "Oh. My. G-d!!!!!!!!!! I'm so happy for you both!!! Xx (sic)"

And Kristin Davis - who has two adopted children - posted: "Yay Yay Yay (sic)"

Chris has previously spoken about his bond with Orion and laughed at the fact the youngster never gets tired of making the same jokes.

He said in the past: "He'll text me poop emojis and then sign, 'Daddy, it's Orion,' and I'm like, 'I know!'. Boys never get over that."

And the actor admitted he was trying to stay as fit as possible in order to keep up with his son.

He said: "The other day I was throwing my kid around on the bed and I pulled a muscle in my back.

"He loves to be thrown around, but he's not as light as he used to be! I lifted him up, threw him on the bed and then it's like, 'Wait a minute, he's 60 pounds.' My back is going, 'Not so fast, partner!'"

"I've got to stay young for him. He's a good inspiration to go to the gym."

The 'Good Wife' star met Tara when she worked in his New York bar the Cutting Room and they welcomed their first son into the world in January 2008.

They got engaged a year later, before marrying on the Hawaiian island of Maui in April 2012.