Duchess of Cambridge Kate Middleton, who is expecting her third child with Prince William, was admitted to a hospital Monday in the early stages of labor, Kensington Palace announced on Twitter.

"Her Royal Highness The Duchess of Cambridge was admitted to St. Mary's Hospital, Paddington, London earlier this morning in the early stages of labour," Kensington Palace said before noting that Prince William arrived at the hospital with Middleton.

"The Duchess travelled by car from Kensington Palace to the Lindo Wing at St. Mary's Hospital with The Duke of Cambridge," the statement continued.

Middleton, 36, and Prince William, 35, announced in September they were expecting their child, due in April.

The couple, who married in 2011, are already parents to 4-year-old son Prince George and 2-year-old daughter Princess Charlotte.

Middleton showed off her baby bump alongside Prince William in February while attending the EE British Academy Film Awards.