Paris Hilton welcomed her first child in January, but it appears that her mother didn't know she was a grandmother until a week after the baby was born.
The 42-year-old welcomed her first child via surrogate with her husband Carter Reum and gave her son a pretty unique name - Phoenix Barron Hilton Reum.
Her fans appeared to have no idea that the DJ, businesswoman, and heiress was expecting a child and were sent into a meltdown when she posted an image of her son's tiny hand on her Instagram.
It would seem that Paris kept her child secret from the world, and even kept it from her family as she revealed that even her mother didn't know.
On a recent episode of her iHeartRadio podcast, This Is Paris, the star revealed that she and her husband decided to keep everything private.
"Not even my mom, my sisters, my best friend knew until he was over a week old," Paris explained on the podcast via PEOPLE. "It was really nice to have that with Carter, be our own journey together. I just feel like my life has been so public, and I've never really had anything be just mine."
Paris explained that her life had always been subject to intense media coverage despite being a "private person" and that her past endeavors had been "invaded" by the media many times.
"I really felt that I wanted this journey to be for us only," Paris went on. "we were so excited and wanted to tell our families, but we were just nervous because if you tell a person, then they tell someone, and all the sudden, it's in TMZ or Page Six, and I've had enough of my life like that.
"So Carter and I literally made a pact together that we would not tell anyone, and no one knew until just recently."
The joyous thing about keeping things secret is the grand reveal and the look of surprise on loved ones' faces, and it seems that is exactly what Paris and Carter got to experience.
"When I introduced my mom to our baby boy, it was amazing to see the look on her face. She was so surprised - just the look on her face, it was priceless," Paris recounted.
On a previous episode of the podcast, Paris revealed the meaning beyond her son's unique name and she also explained how proud she is to be a mother.
"From the moment I laid eyes on him, my heart felt so full. I feel like my life is so complete now. I always wanted to be a mom [...] I'm so happy I found the perfect partner," the star joyfully expressed.
"Carter, he is such an angel and such an incredible father. It's so cute seeing them together and I just love this baby so much. He's laying on my chest and looking up into my eyes, my heart just melts."
Paris has a memoir set to be released on March 14.