(Cover) - EN Showbiz - Nicole Kidman chose to keep her new daughter a secret to protect her.

Earlier this month Nicole and her husband, musician Keith Urban, revealed they had welcomed a baby girl called Faith Margaret, who was born via a surrogate mother on December 28 at The Women's Hospital at Centennial in Nashville. The couple had not previously revealed they were expecting a new arrival and the actress has now explained she wanted to keep her loved ones out of the spotlight until they were ready to share the news.

"We just decided this was our thing together. It kind of just perpetuated itself, Nicole explained on the red carpet at the Screen Actors Guild awards last night. "[And] it protects her and it protects everyone in the situation."

Nicole admits it was a struggle to remain quiet about the new arrival to her family, but the 43-year-old agreed it was best not to discuss it in public.

"I wanted to be able to tell everybody because I was so excited about her," she added. "But at the same time we just decided that this was about being together."

Nicole also has a two-year-old daughter, Sunday Rose, with Keith, as well as two adopted children with her ex-husband Tom Cruise 18-year-old Isabella and Connor, 15.

The Hollywood star went on to explain why the couple chose the name Faith Margaret. Nicole revealed she wanted to pay tribute to beloved family members and her adopted hometown of Nashville where she lives with Keith.

"We needed to have that through the whole pregnancy," she said of the name Faith. "That's what it required - a lot of faith."

"It's that southern double name," Nicole said, before explaining her grandmother was called Margaret and was an inspiration to her when she was growing up. (C) Cover Media