Britain's Prince William, grandson of Queen Elizabeth, and his wife Kate are expecting their second baby and the mother-to-be is once again suffering from very acute morning sickness, his office said on Monday.
The baby will be fourth-in-line to the British throne, following elder brother George, the couple's first child who was born in July last year, his father William and grandfather Prince Charles.
"The Queen and members of both families are delighted with the news that their royal highnesses are expecting their second child,'' Buckingham Palace said in a statement.
There was no detail of when the baby was due.
William's office said Kate, 32, was suffering from Hyperemesis Gravidarum, an acute morning sickness which causes severe nausea and vomiting and requires supplementary hydration and nutrients, a condition that required hospital treatment in the early months of pregnancy with her first child.
George was born in July last year amid a huge international media frenzy, underlying the mass global popularity of the young British royals. Since his birth, George has graced the cover of Vanity Fair and his few public appearances had garnered huge media attention.
There had been huge speculation this year that William, 32, and Kate, officially known as the Duke and Duchess of Cambridge since their marriage in April 2011, would announce a pregnancy.
"Many congratulations to the Duke and Duchess of Cambridge. I'm delighted by the happy news that they're expecting another baby,'' British Prime Minister David Cameron said on his Twitter feed.
Last month William announced that he was to start work as an air ambulance pilot next year based at Cambridge and Norwich in eastern England.