LONDON (December 3, 2012)--Prince William and his wife Kate, 30, the Duchess of Cambridge, are expecting their first child and the duchess was in a London hospital for treatment of a severe form of morning sickness, St. James Palace said Monday.

As the first born to William, who is second in line to the throne after his father, Prince Charles, the couple's first child stands an excellent chance of one day becoming monarch.

Whether boy or girl, the child will be behind Prince William in the line of succession to the throne, Cabinet Office officials said.

The pregnancy is less than 12 weeks along, the palace said.