Buckingham Palace announced Monday that Britain’s Duke and Duchess of Cambridge are expecting their second child!

“The Queen and members of both families are delighted with the news,” the palace said. No due date was mentioned.

Catherine and William’s first child, Prince George, was born in July 2013.

The couple’s second child will become fourth in line to the British throne.

As during her first pregnancy, Catherine is suffering from hyperemesis gravidarum, the palace said. The condition involves involves nausea and vomiting more severe than the typical morning sickness many women suffer during early pregnancy.  She has had to cancel some appearances and is being treated by doctors at Kensington Palace.

Congrats to the growing family!

Photo: Jason Bell/Camera Press via Getty Images