Tyra Banks has always been a private person when it came to her relationships -- and this even goes for her co-workers.
The supermodel announced on Wednesday that she welcomed her first child via surrogate with boyfriend Erik Asla, but sources at her former show FABLife -- which was canceled in January -- tell ET that nobody had any idea that she was expecting a new addition to her family.
WATCH: Tyra Banks Dishes on Chrissy Teigen's Baby News
"We're all talking about it now but we can't figure out how it was kept a secret," one source said of the baby news.
Given how secretive Tyra can be about her loved ones, another source from the show wasn't surprised that she never told them about the surrogate pregnancy. "Tyra is a private person," the source said. "She never talked about her personal life when she was there. She came in, did her s**t and left."
WATCH: Tyra Banks Reveals Her Fertility Struggles and 'Traumatic' Experience With IVF
While she never revealed that she would soon be welcoming a baby of her own, Tyra did shareher struggles with infertility on an episode of the daytime talk show. "I just feel like we’re so hard on each other and judgmental of each other," the 42-year-old TV star said. "A woman that is divorced three times is more normal than a woman that has not been married. I’m so tired of seeing on my social media, ‘Why don’t you have kids? Why don’t you have kids?’ You don’t know. You don’t know what I’m going through, you have no idea."
No one had any idea that, months later, Tyra would have a baby son. "The best present we worked and prayed so hard for is finally here. He's got my fingers and big eyes and his daddy Erik's mouth and chin," she Instagrammed. "As we thank the angel of a woman that carried our miracle baby boy for us, we pray for everyone who struggles to reach this joyous milestone. York Banks Asla, welcome to the world."
WATCH: Tyra Banks May Be Done With FABLife, But Has Other TV Projects in the Works
Here's more details on the supermodel's surprise: