A rare public appearance by Kate Middleton on Tuesday (March 5) has sparked renewed debate about the gender of her baby. 

After a wellwisher gave the Duchess of Cambridge a teddy bear, one woman named Sandra Cook thought she heard the 31-year-old say "Thank you, I will take that for my d…," before she trailed off. 

"You were going to say daughter weren't you?" and she said 'No, we don't know'," Cook, 67, told the Daily Mail. "I said, 'Oh I think you do,',to which she said: 'We're not telling'," Cook added.

Though royal sources continue to insist that Kate and William have yet to find out the sex of their baby, others are already taking yesterday's slip and betting on pink. One U.K. bookmaker even had to suspend operations after being overwhelmed by people placing bets on a baby princess. 

"Although the story is by no means conclusive, our customers came piling in and we were forced to suspend the market 10 p.m. on Tuesday evening," Rupert Adams of Ladbrokes told the Belfast Times

Whatever the speculation, it will all come to an end sometime in July when Kate is expected to give birth. Till then, your guess is as good as anyone else's! 

Check out ABC video of Kate's possible slip-up below.

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Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

Is Kate Middleton having a girl?
Speculation explodes as the Duchess of Cambridge mistakingly drops a hint about her baby's gender.