"On Monday we had a message from Terry saying: 'hi team, happy new year. I've just tuned in and I'm wondering if I've missed a special announcement. Is Hayley pregnant? Or is it just today's outfit? Her bust and belly look quite full.'
"Now Terry I am terribly offended," she said in a joking way.
She continued: "I'd get angry and I'd send someone over to see you if in fact it wasn't true.
"Because yes Terry, I am pregnant," she confirmed.
"I've finally told everybody, which is so awkward," says Holt.
The 39-year-old went on to say: "I'm so happy because I wanted this for a very, very, very long time and I thought my time was running out and it hasn't."
Viewers expressed their delight for the news on social media.
One viewer tweeted: "Ahh! Tears of joy for you here on the couch. Congratulations. What wonderful news to start the year off."
A Facebook user commented: "That is wonderful news, congratulations!"
Fellow Breakfast hosts John Campbell, Matty McLean and Jenny May Clarkson congratulated Holt on the news.
In October last year, Holt was outspoken about her five years of sobriety on the show, saying deciding to go sober was "the best decision ever."