Katherine Heigl and husband Josh Kelley welcomed baby boy Joshua Bishop Kelley Jr. on December 20th, 2016. Joshua Jr. is the couples third child, with the 7 lbs. 15 oz. baby boy joining older sisters Naleigh (Nancy Leigh), 8 and Adalaide, 4.

Katherine Heigl Introduces Baby Joshua Bishop Kelley Jr.

People caught up with the family at their home in rural Utah for a cover feature, where Katherine introduced the newborn.

"It was a surprise! I knew I wanted to expand our family, I knew I wanted to have more children," Katherine explained to People at her Utah ranch for this week’s cover story. "I just didn’t know how we were going to go about that."

Katherine said that as a person who plans and schedules everything, finding out she was pregnant just as she was back at work on her new CBS series, Doubt (premiering Feb. 15) wasn’t ideal. "I’ll be totally honest, my first reaction was ‘Oh s–!,’" she says. "But now we have a new normal, and I have to give myself a break in order to get used to it."

"This little boy is going to have all these girls fawning over him," Katherine exclaimed, revealing Joshua Jr. has a third honorary big sister right now: niece, Madison, 15, who currently lives with the family on the ranch to focus on her budding equestrian passion.

Now that she’s set to go back to work promoting Doubt next month, Katherine is chilling out in that fawning stage. "We’re at the point where we’re really obsessed with him!" she says. "With a newborn, you’re forced to be still – and you have this beautiful reason to do that."

Even though she and her family are still adjusting to life with the little guy, Katherine knows that she’s not done growing her family.

"I’d get pregnant again, and I still am very inspired by adoption. I also have been thinking a lot about fostering. It’s all up in the air," she says with a smile. "And I’m okay with that!"

For more from the interview and the Cheyenne Ellis photoshoot, pick up the latest issue of PEOPLE, on newsstands Friday, January 27th, and visit the People website.

Watch the full cover story video on the People Entertainment Network