The actor went on to confirm the baby news on Facebook, writing: "Um. I don't know if it's a 'man's world,' but I'm certain women run it. Susan and I are therefore delighted to announce we are expecting a baby. Girl. November."
This will be the first girl for Robert and his wife Susan, who gave birth to their son Exton Elias in February 2012.
Robert also has an adult son, Indio, with ex-wife Deborah Falconer.