The 29-year-old princess said no to the protein snack as she and hubby William joined the Danish Crown Prince and his wife at a famine relief depot in Copenhagen.
Pregnant women are encouraged to avoid peanuts due to a potential link to allergies.
An onlooker said: “The Duchess does not have a nut allergy, nor is it like her to appear rude. The only explanation is that she is pregnant and has been told — like many expectant mothers — to avoid nuts.”
Prince Frederik, Princess Mary and Wills all tucked into the paste, while Kate declined and gave William an odd look.
Kate’s official spokesman has confirmed that she isn’t allergic to nuts.
Ladbrokes have now suspended bets on Kate and Wills having a baby before the Queen’s Diamond Jubilee in June next year.
But a senior source said: “Pregnancy is not the only explanation. The Duchess is still new to appearing in front of the cameras at official events.
“It is perfectly plausible that she may not yet feel comfortable eating while the cameras are focused on her. This is not the first time she’s turned down food while under the spotlight.”
If Kate is pregnant and has a girl, the baby could grow up to be Queen under new rules.
Earlier this year, Royal biographer Andrew Morton said Kate would be pregnant within months of the royal wedding
