Kate Middleton's pregnancy illness has forced her to cancel an appearance at the UK premiere of The Hobbit.
The Duchess of Cambridge is suffering from severe morning sickness, which leaves expectant mothers with constant nausea and regular vomiting.
A St James's Palace spokesman said: "The Duchess of Cambridge will not attend The Hobbit premiere tomorrow evening and will continue to rest privately.
"The Duke of Cambridge will attend as planned."
The latest blockbuster from director Peter Jackson, who created the popular Lord Of The Rings movie trilogy, is to screen in London on Wednesday.
Over the weekend, the duchess's bouts of vomiting intensified to such a degree the duke pulled out of the British Military Tournament on Sunday evening to be with her.
St James's Palace has stressed it will not be giving daily updates on Kate's health.
However, it says while she is still suffering from the condition she is experiencing less vomiting, so William feels able to attend the premiere.