LONDON - The Duchess of Cambridge says she doesn't know the sex of her first child -- but she hopes it's a boy.

Her husband Prince William, however, would prefer a girl.

The former Kate Middleton, who is five months pregnant, made the revelation to a soldier Sunday at a St. Patrick's Day ceremony honoring the Irish Guards.

Guardsman Lee Wheeler said the duchess told him: "I'd like to have a boy, and William would like a girl."

The duchess wore a green dress coat and a shamrock lapel pin as she presented sprigs of shamrock to soldiers in the annual ceremony at a barracks in Aldershot, southern England.

She suffered a minor mishap when one of her high heels became briefly stuck in a drainage grille.