The 39-year-old recently returned to work after giving birth to her little boy Ethan in July.
Her partner Kris Smith, a British model, has been looking after Ethan while she works.
In her Glamour magazine column, she said: 'Kris has been called in for 'Superdad' duties since I'm busy in the studio mentoring my other babies - the X Factor boys!'
The Aussie singer added that she has been covering the baby in glitter by accident after returning to the show.
She said: 'I was feeding Ethan last night and noticed something on his head that caught my eye. Every new mother goes into an instant frenzy: 'What is it? Something bad? A mark? A scrape?'
'No, it was a piece of glitter - Mum is most definitely back at work!'