The 23-year-old fell pregnant after a relationship with Irish model Jeremy McConnell, whom she met in the January 2016 series of the Channel 5 show.
There have been rumours that Steph would return to CBB in 2017 with her newborn baby, but she denied the claims in her latest OK! column.
"Just to be clear, I definitely won't be," Steph told fans.
"I was asked to return to the show but I'll be at home focusing on being the best mum I can be, that's for sure. I thank CBB for so much though and for the journey it put me on. If it wasn't for them, I wouldn't have my son."
Steph added: "I'm not sure if I'd ever go back on though. Sometimes I think it would be good to go back and show them how much I've grown in the past year. I'm sure it will be a great series though."
The former Hollyoaks actress had us all hooked thanks to her flirtatious relationship with Jeremy, 27, in the house, despite Steph having a boyfriend, model Sam Reece, on the outside.
Once the show ended, Steph and Sam split and she began to date Jeremy, but their relationship was rocky, with multiple public splits and reunions until they broke up for good in May. Steph then announced her pregnancy and later confirmed it will be a baby boy.
Jeremy has publicly questioned whether he is the baby's father and has asked for a DNA test after the birth. Steph, however, has insisted Jeremy is the dad.