London(USA Today/WLTX)- Prince George and Princess Charlotte are getting a younger sibling. In a surprise announcement, Kensington Palace revealed on Monday morning that Prince William and Duchess Kate were expecting their third child.

As with her other two pregnancies, the Duchess is suffering from Hyperemesis Gravidarum, a form of severe morning sickness, and was forced to cancel her engagements Monday.

"The Queen and members of both families are delighted with the news," the palace said in a statement released on Twitter.

William and Kate already have two children, Prince George, 4, and Princess Charlotte, 2.