LONDON, England - Catherine, Duchess of Cambridge, or Kate, as she's known to most of the world, delivered she and Prince William's third child on Monday; a little brother for Prince George and Princess Charlotte. Kensington Palace confirmed in a tweet that both mother and baby were doing well, and that Prince William was there for the birth.

Kate arrived Monday morning  in "the early stages of labor" at St. Mary's Hospital in London and was admitted to the Lindo Wing, where she had already given birth twice. She and William arrived together by car. 

The new prince's name was not immediately announced.

Known simply as Kate Middleton before her royal life began, the Duchess announced she was pregnant with her third child after missing a royal engagement in September. As with her other two pregnancies, she suffered from hyperemesis gravidarum, or acute morning sickness.

The couple's second child, Princess Charlotte, began attending nursery school in London in January at the age of two. She turns three in May. Her big brother Prince George is four and began school in September last year.

The baby boy is now fifth in line to the British throne, after grandfather Prince Charles, father William, Prince George and sister Princess Charlotte. He is Queen Elizabeth II's sixth great-grandchild.