Duchess Catherine has been eating ginger biscuits to try to relieve her morning sickness.
The Duchess of Cambridge has been suffering from hyperemesis gravidarum - an extreme form of acute morning sickness - for the third time so has been chowing down on the calorific treats in an attempt to make her feel better.
Speaking at an awards ceremony for the Metropolitan and City Police Orphans Fund, Prince William - who is patron of the group - told 98-year-old Iris Orrell his wife has been trying the biscuits but they haven't been doing much good.
He said: "There is not much ginger can do to stop that. We've done all that."
It is believed by some that ginger can help to relieve nausea and morning sickness.
William and Catherine, both 35, revealed earlier this month they were expecting their third child - a sibling for Prince George, four, and two-year-old Princess Charlotte - and confirmed the royal was suffering from morning sickness.
A Kensington Palace statement read: "Their Royal Highnesses The Duke and Duchess of Cambridge are very pleased to announce that The Duchess of Cambridge is expecting their third child. The Queen and members of both families are delighted with the news.
"As with her previous two pregnancies, The Duchess is suffering from Hyperemesis Gravidarum. Her Royal Highness will no longer carry out her planned engagement at the Hornsey Road Children's Centre in London today.
"The Duchess is being cared for at Kensington Palace."
Shortly after the statement was released, William's brother Prince Harry admitted Catherine was "OK".
He said: "I haven't seen her for a while but I think I she's OK."