London:
Prince William and Kate Middleton are expecting their second baby in April next year, raising the possibility the new royal birth will coincide with their wedding anniversary, or the Queen's birthday.
The Duke and Duchess of Cambridge announced the expected date as Kate prepares for her first official engagements since she announced she was pregnant with her second child.
"Their Royal Highnesses The Duke and Duchess of Cambridge are delighted to confirm they are expecting a baby in April 2015," Kensington Palace said in a statement.
"The Duchess of Cambridge continues to be affected by hyperemisis gravidarum, but her condition is steadily improving," it said.
Their announcement was made after the 32-year-old Duchess passed the 12-week mark in her pregnancy, suggesting a due date in late April.
The date could coincide with the Queen's 89th birthday, on April 21, or the Duke and Duchess's wedding anniversary on April 29.
Any later and the baby will arrive as the country prepares to vote in next year's general election on May 7.
The baby will become the fourth in line to the throne, behind Prince George.
The Queen has said she is "delighted" at the news that comes just a year after the birth of the couple's first child Prince George in July last year.
The Duchess' pregnancy had already been announced in September but the due date had not been released.
She will make her first public appearance tomorrow since her pregnancy was announced last month as she joins Prince William to officially welcome Singapore's President Tony Tan for his four-day visit to the UK.
The duchess will also attend the Wildlife Photographer of the Year awards ceremony at the Natural History Museum here.
The second royal baby in April 2015 is unlikely to generate as much excitement as its older sibling Prince George, because of the relatively smaller chance of him or her being the future king or queen of England.
For the second time, the duke and duchess have been forced to announce a pregnancy before the duchess passed the significant 12-week milestone as she suffers from acute morning sickness called hyperemesis gravidarum, a condition that may require supplementary hydration, medication and nutrients.
It 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.
