The 'Mysterious Girl' singer was promoting his fragrance on Saturday, 26 July when one attendee hoping for a signed bottle that day ended up welcoming a baby instead.
Peter tweeted: "So yesterday I was signing bottles of my perfume and as I was talking to this lady, she went into labour.
"She now has a beaut baby. Wow."
He jokingly added: "So my perfume can officially put you in labour."
No doubt doting dad Peter, 41, knew just what to do, as he's a father of three: son Junior and daughter Princess from his marriage to ex-wife Katie Price, and baby Amelia from his relationship with fiancée Emily MacDonagh.
Peter and Emily welcomed adorable Amelia in January this year.
Last week, trainee doctor Emily was seen carrying six-month-old Amelia into the ITV studios, where Peter was a guest on Let's Do Lunch With Gino And Mel.
Peter recently told Reveal: "Amelia is a mini Ems! Her nose is mine, but the rest of her is Emily. I want her to have Emily's intelligence. I want her to be a brainiac. And I want her to look like Emily. But I also want her to have my creativeness and drive."
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Stars who welcomed babies in 2014:
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