The Duke and Duchess of Cambridge say their third child will be due in April.
The royal couple had already revealed that they were having a child, but didn't previously say which month the child is due. The brief statement released Tuesday by their Kensington Palace office offered no further details.
The former Kate Middleton had announced she was pregnant after missing a royal engagement in September. As with her other two pregnancies, she is suffering from hyperemesis gravidarum, or acute morning sickness.
She has since appeared in other events, including one Monday in which she danced with a person dressed as the beloved British children's book character, Paddington Bear.
William and Kate, both 35, already have two children: Prince George, 4, and Princess Charlotte, 2.