ABC News' Amanda Keegan and Linsey Davis report:

For four laugh and cry-out-loud seasons, Laura Linney was the no-nonsense mom battling terminal cancer on Showtime's "The Big C."

And now in an unexpected plot twist right out of Hollywood, after nine months of keeping her latest role a secret, Linney, 49, has revealed she's no longer just playing a part on TV. She is now a mother in real life.

"Laura gave birth to a healthy boy named Bennett Armistead on January 8 th," Raha Lewis, a writer for People magazine, told ABC News.

This is the award winning actress's first child with husband of three years, Marc Schauer. And despite their life in the limelight, for the entire term of her pregnancy, Linney kept it a secret.

"Not many people knew she was pregnant, but we know she's home now enjoying being a mother," said Lewis.

Linney was last photographed at a Hollywood event in June, flaunting a figure-hiding jumper with no baby bump in sight.

In September, she took home an Emmy for best actress in a miniseries or movie but wasn't there to accept her award.

"Laura couldn't be here tonight. She's such a great actress that she didn't even need to show up," Matt Damon joked while presenting the award.

Just shy of 50 years old, Linney joins a growing list of Hollywood A-list moms who sported baby bumps later in life, from Salma Hayek at age 41, to Halle Berry at age 47 and Kelly Preston at age 48.

But doctors point out the risks associated with pregnancies later in life can increase with age.

"Biologically we are really meant to reproduce in our early twenties, not in our late forties," said ABC N ews medical contributor Dr. Jennifer Ashton.

" But that doesn't mean there can't be exceptions and there can't be women 49 years of age who are healthy, in great shape and can go through a very uneventful pregnancy and have a very healthy baby," Ashton said.

(Barry King/Getty Images)