Actress Kym Whitley has opened up about her life as a first-time mother after adopting her troubled friend's baby, calling her son the best "gift" she "never asked for".

The Along Came Polly star became an overnight mum when a young friend fell pregnant in 2011 and decided to give up her child in the hope that little Joshua would have a better life with Whitley.

The actress details her struggles with parenthood in new U.S. Tv docu-series Raising Whitley and during the show's first episode she recalled the shock of literally becoming a mum overnight after receiving a surprising call, which changed her life forever.

She said, "(My career) was on fire. And then I got the call. 'Hello, this is the hospital calling. We have your baby ready.' I was like, 'I didn't order a baby! Oh, there has to be a mistake.'"

However this was no mistake and a social worker explained that her pal had chosen the actress as the baby's guardian and if Whitley didn't take in the newborn, he would be put into the foster care system - so the 51 year old nervously obliged: "An hour and a half later: Ding dong! There's Joshua. I had no idea how to take care of a baby!"

Now, two years later, Whitley knows she made the right decision to take the baby in: "He was a gift that I'd never asked for."