Royal pregnancy: Duchess leaves hospital

The Duchess of Cambridge has left hospital after several days of treatment for acute morning sickness.

Catherine, holding a bouquet of yellow roses, left King Edward VII hospital in central London on Thursday morning with her husband, Prince William.

Less than 12 weeks pregnant, she was admitted with acute morning sickness - hyperemesis gravidarum - on Monday.

St James's Palace said in a statement that she was now heading to Kensington Palace for a period of rest.

Her first child will be third in line to the throne, and will become monarch, whether a boy or a girl, after changes to the succession rules.

This week the Commonwealth governments agreed to press ahead with a bill ending discrimination against women in the succession to the British throne.

Catherine smiled at the media, which have been assembled outside since her admission, when she emerged from the hospital.

She nodded when asked by reporters if she was feeling better.

BBC royal correspondent Luisa Baldini said the duchess seemed tentative and less energetic than usual.

A public announcement of the duchess' pregnancy, before the usual three-month mark, was prompted by her medical condition.

St James's Palace added: "Their Royal Highnesses would like to thank the staff at the hospital for the care and treatment the duchess has received."

Catherine's father-in-law, the Prince of Wales, said he was "thrilled" at the pregnancy.

"It's a very nice thought to become a grandfather in my old age," said the 64-year-old heir to the throne, at HMS Belfast in London, where he was visiting the vessel which will accompany Sir Ranulph Fiennes' Antarctic expedition.

Catherine's discharge from hospital comes the day after it emerged that two Australian radio DJs impersonated the Queen and the Prince of Wales to dupe hospital staff into giving an update on the duchess's condition.

The hospital said confidentiality was taken seriously and telephone protocols are under review.

2Day FM said it was surprised their call was put through but "sincerely apologises".

The Australian Communications and Media Authority said it has received complaints about the prank call.

The privacy provisions of the commercial radio codes of practice apply to news and current affairs programmes, it said, but added that it had no further comment to make.

Catherine is not expected to attend any scheduled engagements for the time being, but Prince William will continue with his royal duties, including two events at the weekend.

It is not uncommon for pregnant women to experience morning sickness, particularly during the first few months of pregnancy, but some women (around one in every 200) experience severe nausea and vomiting, which continues throughout.

This condition is known as hyperemesis gravidarum or HG and needs specialist treatment and often requires a stay in hospital.

The main danger is dehydration - it can be difficult to keep enough fluid down orally, and doctors can treat HG with medication to help ease the nausea.