Prince William visits pregnant Kate in hospital

Prince William visited his pregnant wife, Kate, at a London hospital on Tuesday, where she is spending a second day being treated for acute morning sickness.

William, 30, arrived at the King Edward VII private hospital just before noon. He was seen leaving the same hospital on Monday evening, wearing a gray sweater and walking to a waiting car.

Kate may also have other visitors on the way -- her parents, Michael and Carole Middleton, were photographed separately leaving their home in Bucklebury, England, on Tuesday morning, according to the Daily Mail.

The Duchess of Cambridge, 30, is suffering from hyperemesis gravidarum, a potentially dangerous type of morning sickness in which vomiting is so severe no food or liquid can be kept down.

She was admitted to the hospital Monday, the same day the pregnancy was announced. The palace said she was expected to remain there for several days and would require a period of rest afterward. Her public engagements have been cancelled for the next week, the AFP reports.

The palace would not say how far along the duchess is, only that she has not yet reached the 12-week mark.

Kate's pregnancy was announced in a statement Monday that said, "Their Royal Highnesses The Duke and Duchess of Cambridge are very pleased to announce that The Duchess of Cambridge is expecting a baby. The Queen, The Duke of Edinburgh, The Prince of Wales, The Duchess of Cornwall and Prince Harry and members of both families are delighted with the news."

The announcement quickly sparked reactions around the world. Kate Middleton, #Kate and #royalbaby all became top trends on Twitter after Monday's announcement, and congratulations came from well-wishers including British Prime Minister David Cameron, who said, "I'm delighted by the news that the Duke & Duchess of Cambridge are expecting a baby. They will make wonderful parents."

Her pregnancy comes after a 2011 decision by the leaders of Britain and 15 Commonwealth nations endorsing new rules that give girls equal status with boys in the order of succession. Experts caution that laws to enact the change have not yet been passed, which could cause uncertainty if the baby is a girl.

William and Kate's child would be third in line for the throne, behind William and his father, Prince Charles. Prince Harry, who is currently third in line, would be bumped down to fourth.