"They haven't been keeping it private really, she's just been working on her business with her family so she hasn't been around," a source told Us. "She's expecting very soon."
Family, friends and her sisters feted the coming baby by offering Byxbee a baby shower last weekend in L.A., said the source.
The Hawaii Five-O star talked about his relationship with Byxbee during an appearance on Chelsea Lately in January 2013.
"She should get the purple heart because I'm a complete disaster," he said.
The couple live together in Hawaii so Caan can shoot Hawaii Five-O. However, the 37-year-old hottie said the "relaxed" nature and lack of "hustle" in Hawaii — where the couple first met — isn't exactly his idea of paradise.
"Everything's very slow-motion. I pick up the cup and they slowly pick of the cup," he joked.
— Us Weekly (@usweekly) June 11, 2014
This will be the first child for the couple who have been together for a "couple of years."
Scott's father, James Caan, is said to be very excited to become a grandfather.
"His dad James is really close with him," the insider told Us. "He is very excited."
Image via Wikimedia Commons