"We're Expecting!!!!!" she captioned a photo of her, her 3-year-old daughter Marley Rae and her boyfriend Michael Sterling. "5 months in and we couldn't be more excited!!! [Sterling] gets a mini me and #Marley gets a sidekick."
This will be Marcille's first baby with Sterling, as Marley Rae's father is ex Kevin McCall.
The America's Next Top Model winner opened up more about the sex of the baby to PEOPLE.
"I said, 'Marley, would you like to have a little brother or sister?' And she said, 'Yes, Mom, but you know what? Maybe a baby brother. Make it a brother,'" Marcille recalled. "I thought that was adorable, but at the time, I had no idea what I was having, so my fear [about] this extremely expressive and outgoing young girl [was] if this baby came out to be a little girl, that might not be a great situation for Marley."
She continued, "However, I found out soon after that I was having a boy, and I felt like she willed it in her favor. I'm beyond elated to be having a boy."
Photo credit: Instagram/@EvaMarcille