A representative for the Palace just released a statement of the Duchess of Cambridge’s condition:
"The Duchess of Cambridge is continuing to feel better. She and the duke are immensely grateful for the good wishes they have received. She will remain in hospital at present and will continue to be treated for hyperemesis gravidarum."
On the same day that the Palace announced Middleton was with child, they also announced that she had been rushed to the hospital.
Hyperemesis gravidarum is a rare maternity illness that have symptoms of extreme morning sickness. She is expected to stay there for several days.
According to medical experts, the rare illness could be an indication that the Duchess is pregnant with twins.
"Their Royal Highnesses the Duke and Duchess of Cambridge are very pleased to announce that the Duchess of Cambridge is expecting a baby," a rep for St. James’ Palace announced on Monday. "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 Duchess was admitted this afternoon to King Edward VII Hospital in Central London with hyperemesis gravidarum," the palace continued in a statement. "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."
Prince William and Kate Middleton are both 30, and this will be their first child or first two children if the Dutchess is in fact pregnant with twins.