(CNN) -- Another royal baby is on the way.
Britain's
Duke and
Duchess of Cambridge are expected to become parents for a second time, Buckingham Palace announced Monday.
"The Queen and members of both families are delighted with the news," the palace said. It didn't say when the due date will be.
As during her first pregnancy, Catherine is
suffering from hyperemesis gravidarum, the palace said. The condition involves nausea and vomiting more severe than the typical morning sickness many women suffer during early pregnancy.
She is being treated by doctors at Kensington Palace and didn't accompany Prince William on a planned visit Monday to Oxford.
The decision to announce the pregnancy was made when it became apparent Catherine was not well enough to go on the Oxford trip and that a number of other forthcoming engagements could be affected, a royal source told CNN.