Paris Hilton kept the arrival of her newborn son a secret even to her family members until the last minute.

"My entire life has been so public," the 42-year-old reality TV star and entrepreneur explained in a Harper's Bazaar interview.

Hilton disguised herself with a brunette wig, a hoodie and a fake name when she checked into the hospital on the day her son was born. Only she, her husband Carter Reum and their surrogate knew about the baby's impending arrival at the time. Their immediate families knew about it only after she announced it on her Instagram page.

"I've never had anything for myself. We decided that we wanted to have this whole experience to ourselves," Hilton told the outlet.

Once out of the hospital, the couple pulled out all the stops to hide the news about their son even from their employees. Hilton and her venture capitalist husband told their staff they were having their house painted to make sure no one else was at home during the baby's arrival. The new parents enjoyed their time with the baby for two full days. Hilton later announced the news on her Instagram page before it was leaked to the media.

The socialite shared a sweet photo of the baby's hand holding her thumb last month and wrote, "You are already loved beyond words."

The "This is Paris" star enjoys singing lullabies to her baby and "Twinkle, Twinkle, Little Star" is her favorite. She said she even sings the acoustic version of her 2006 hit, "Stars Are Blind," to her baby.

Hilton also opened up about the difficulties she faced in her own childhood, which helped her realize what she wants for her own family.

"I want to protect him and to be with him every second. You have this mother instinct that kicks in, which I've never had before. I feel so complete now," the "Simple Life" alum said.

Hilton first spoke about the couple's decision to become parents back in December.

"We just wanted to really enjoy our first year of marriage together as a couple, and we were always planning on 2023. And we've just, you know, getting the eggs all ready. They're all ready and they're all waiting and excited for them," she said at the time.

Paris Hilton
Paris Hilton is pictured arriving at the Fashion For Relief Cannes event on May 13, 2018, at Cannes Mandelieu Aeroport, southern France. Yann Coatsaliou/AFP/Getty Images