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Prince William and his wife Catherine, Duchess of Cambridge, are expecting their third child, Kensington Palace announced.

Looks like those baby rumours were true after all!

Kensington Palace made the pregnancy announcement early on the morning of Monday, September 4, after saying that the Duchess of Cambridge was too sick to attend an engagement scheduled for later in the day. As was the case with her other two pregnancies, the Duchess is suffering from Hyperemesis Gravidarum, defined as acute morning sickness.

"The queen and members of both families are delighted with the news," the palace said in a statement. The latest addition to the royal family will join big brother, Prince George, 4, and Princess Charlotte, 2.

Read the full statement from Kensington Palace here:

It's a big week for the young royal family and William and Catherine are set to send George to school for the first time on Thursday. He will attend Thomas's Battersea in south London, near the family's new apartment in Kensington Palace. The family recently moved from their Norfolk home Anmer Hall to be closer to George's school.

Currently, no details were available about when the third baby is due.

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