Britain's Prince William and Kate, Duchess of Cambridge pose for a photo with their newborn baby son as they leave the Lindo wing at St Mary's Hospital in London. Kirsty Wigglesworth/AP hide caption toggle caption Kirsty Wigglesworth/AP The Two-Way It's A Boy! Prince William And Duchess Catherine Welcome No. 3 April 23, 2018 The new prince was born Monday and weighed 8 pounds, 7 ounces. Mother and child are "both doing well," Kensington Palace announced.