The pregnant 38-year-old, who is mum to two-year-old son Art with her husband Chris O’Dowd, said the maternal instinct just came to her one day.
“But I woke up one day like... fill my womb!”
O’Porter said that her first child, Art, was planned.
“Yes, we planned the first baby,” she added. “I think Chris would have been disappointed if it hadn’t have happened.
“He’s a natural dad, he’s from good Irish stock - I knew he’d be brilliant. He’s blown my mind. He’s very hands on.”
The TV presenter is due to give birth to the couple’s second child in July, and said she’s hoping for a home birth.
She also explained how she felt her childhood had influenced how she is with her son, adding: “My view is that as long as a child is loved you’ll be fine.”
O’Porter made the announcement at the end of her latest ‘Get It On’ podcast.
She said: “So I hope your 2017 is going really well. Mine certainly is.
“I am starting a new novel this week, I’m about to turn 38 and... I am pregnant.
“So I’ll be investing in a lot of elasticated trousers and dusting off all my old vintage tents, not unlike a lot of people in January.”
‘Loose Women’ is on weekdays from 12.30pm.