Catherine leaves hospital

Updated at 4:03 pm on 7 December 2012

The Duchess of Cambridge has left hospital, four days after she was admitted for acute morning sickness.

Holding a bouquet of yellow flowers, Catherine emerged from King Edward VII hospital in central London on Thursday morning beside her husband.

The duchess 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.

Catherine smiled at the media when she emerged from the hospital. She nodded when asked by reporters if she was feeling better.

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

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 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.

The BBC reports this condition is known as hyperemesis gravidarum, which 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.

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