Little brother or sister for Prince George
Kate Middleton and Prince William are expecting their second child.
Buckingham Palace made the announcement Monday on Twitter.
An officials statement also says the Duchess is suffering from extreme morning sickness, similar to her first pregnancy.
She was admitted to the hospital while pregnant with Prince George.
Kate Middleton is currently being treated by doctors at Kensington Palace.
The new baby will be fourth in line for the throne behind Prince George, who turned one in July.