FILE - In this Monday, Sept. 17, 2012 file photo, Britain's Prince William and his wife Kate, the Duke and Duchess of Cambridge, smile as they listen to a village chief who makes a speech after they arrived at Marapa Island, Solomon Islands. Prince William and his wife Catherine are expecting their first child. St. James’s Palace announced the pregnancy Monday, saying that the Duchess of Cambridge, formerly known as Kate Middleton has a severe form of morning sickness and is currently in a London hospital. William is at his wife’s side. (AP Photo/Rick Rycroft, Pool, File)

LONDON: Prince William’s wife, Catherine, spent last night in hospital where she is being treated for acute morning sickness, following the announcement that the couple are expecting their first child.

The family revealed the news yesterday, ending fevered speculation about a baby destined to become Britain’s monarch, whether it is a boy or a girl.

St James’s Palace also said Kate, 30, was in hospital suffering from “hyperemesis gravidarum”.

Queen Elizabeth and the rest of the royal family were “delighted” by the news of the pregnancy while William – the son of the late Princess Diana and the heir to the throne Prince Charles – had visited her in hospital, the palace said.

The pregnancy adds to resurgent support for the monarchy after the pomp of William and Kate’s wedding in April last year and the diamond jubilee celebrations to mark the queen’s 60th year on the throne in June.

The baby is set to be third in line to the British throne after Charles and William, irrespective of its sex, following moves by the government to change ancient succession laws giving priority to male children.

The palace said the couple were only “recently” aware that Kate, pictured, was pregnant.

It was reported that the pregnancy has not passed the 12-week point and that the announcement was prompted by her medical condition.

The palace said Kate was admitted to the King Edward VII Hospital in central London yesterday afternoon with hyperemesis gravidarum, which it defined as “very acute morning sickness”, which requires extra hydration and nutrients.

“As the pregnancy is in its very early stages, Her Royal Highness is expected to stay in hospital for several days and will require a period of rest thereafter,” the statement said.

William, also 30, visited his wife last night, before leaving in a flurry of flashbulbs. – Sapa-AFP