Britain's Prince William stand next to his wife Kate, Duchess of Cambridge as she leaves the King Edward VII hospital in central London, Thursday, Dec. 6, 2012. Prince William and his wife Kate are expecting their first child, and the Duchess of Cambridge was admitted to hospital suffering from a severe form of morning sickness in the early stages of her pregnancy. (AP Photo/Alastair Grant)
Britain's Prince William stands next to his wife Kate, Duchess of Cambridge as she leaves the King Edward VII hospital in central London, Thursday, Dec. 6, 2012. Prince William and his wife Kate are expecting their first child, and the Duchess of Cambridge was admitted to hospital suffering from a severe form of morning sickness in the early stages of her pregnancy. (AP Photo/Alastair Grant)
Britain's Prince William stands next to his wife Kate, Duchess of Cambridge as she leaves the King Edward VII hospital in central London, Thursday, Dec. 6, 2012. Prince William and his wife Kate are expecting their first child, and the Duchess of Cambridge has been admitted to hospital suffering from a severe form of morning sickness in the early stages of her pregnancy. (AP Photo/Alastair Grant)
Two policemen stand guard outside the King Edward VII hospital where Kate Duchess of Cambridge is receiving treatment in central London, Wednesday, Dec. 5, 2012. Prince William and his wife Kate are expecting their first child, and the Duchess of Cambridge has been admitted to hospital suffering from a severe form of morning sickness in the early stages of her pregnancy. (AP Photo/Alastair Grant)
Britain's Prince William stands next to his wife Kate, Duchess of Cambridge as she leaves the King Edward VII hospital in central London, Thursday, Dec. 6, 2012. Prince William and his wife Kate are expecting their first child, and the Duchess of Cambridge was admitted to hospital suffering from a severe form of morning sickness in the early stages of her pregnancy. (AP Photo/Alastair Grant)
Britain's Prince William stands next to his wife Kate, Duchess of Cambridge as she leaves the King Edward VII hospital in central London, Thursday, Dec. 6, 2012. Prince William and his wife Kate are expecting their first child, and the Duchess of Cambridge has been admitted to hospital suffering from a severe form of morning sickness in the early stages of her pregnancy. (AP Photo/Alastair Grant)
Britain's Prince William arrives at the King Edward VII hospital to visit his wife the Duchess of Cambridge in central London, Thursday, Dec. 6, 2012. Prince William and his wife Kate are expecting their first child, and the Duchess of Cambridge has been admitted to hospital suffering from a severe form of morning sickness in the early stages of her pregnancy. (AP Photo/Alastair Grant)
Britain's Prince William, center, leaves the King Edward VII hospital in central London where Kate, the Duchess of Cambridge has been admitted with a severe form of morning sickness, Wednesday, Dec. 5, 2012. Prince William and his wife Kate are expecting their first child. The Duchess of Cambridge is expected to stay in the hospital for several days and will require a period of rest afterward. (AP Photo/Sang Tan)
Britain's Prince William, center, leaves the King Edward VII hospital in central London where Kate, the Duchess of Cambridge has been admitted with a severe form of morning sickness, Wednesday, Dec. 5, 2012. Prince William and his wife Kate are expecting their first child.The Duchess of Cambridge is expected to stay in the hospital for several days and will require a period of rest afterward. (AP Photo/Sang Tan)
Britain's Prince William leaves a hospital in central London, Wednesday, Dec. 5, 2012. Kate, The Duchess of Cambridge is being treated at the hospital for severe morning sickness. (AP Photo/Lefteris Pitarakis)
Britain's Prince William leaves a hospital in central London, Wednesday, Dec. 5, 2012. Kate, The Duchess of Cambridge is being treated at the hospital for severe morning sickness. (AP Photo/Lefteris Pitarakis)
Britain's Prince William leaves a hospital in central London, Wednesday, Dec. 5, 2012. Kate, The Duchess of Cambridge is being treated at the hospital for severe morning sickness. (AP Photo/Lefteris Pitarakis)
Britain's Prince William leaves a hospital in central London, Wednesday, Dec. 5, 2012. Kate, The Duchess of Cambridge is being treated at the hospital for severe morning sickness. (AP Photo/Lefteris Pitarakis)
Britain's Prince William leaves a hospital in central London, Wednesday, Dec. 5, 2012. Kate, The Duchess of Cambridge is being treated at the hospital for severe morning sickness. (AP Photo/Lefteris Pitarakis)
Britain's Prince William leaves a hospital in central London, Wednesday, Dec. 5, 2012. Kate, The Duchess of Cambridge is being treated at the hospital for severe morning sickness. (AP Photo/Lefteris Pitarakis)