The Duke and Duchess of Cambridge will announce tomorrow whether Kate is well enough to travel to Malta for her first official solo overseas tour, Kensington Palace has said.
William and his pregnant wife Kate, who has been suffering from a severe form of morning sickness, will consult her doctors this evening as they make their final decision.
It is likely a member of the Royal Family is on standby to take the Duchess's place if the conclusion is she will not travel to Malta this weekend to celebrate the 50th anniversary of the nation's independence.
A Kensington Palace spokesman said: " The Duke and Duchess will make a final decision this evening, in consultation with the Duchess's doctors, a n announcement is expected tomorrow morning."
The Duchess is suffering from another bout of the illness hyperemesis gravidarum which she experienced during the early stages of her first pregnancy.
Kate, who is expecting her second child, was also forced to cancel a number of engagements last week after her pregnancy was announced last Monday.
Her pregnancy has not passed the 12-week stage and there is speculation that the royal couple's second child could be due in April next year.
Hyperemesis gravidarum, which affects 3.5 per 1,000 pregnancies, causes severe vomiting and can lead to dehydration, weight loss and a build-up of toxins in the blood or urine, called ketosis.
Kate has been treated at home by medical staff and at the beginning of last week William said they had experienced a ''tricky few days''.