Newsom told the San Francisco Chronicle over the weekend that he was elated by the news. The former San Francisco mayor said the child will be the couple's "third and last," according to the newspaper.
Newsom and his wife, Jennifer Siebel Newsom, have two children, Montana, 3 1/2, and Hunter, 1 1/2.
Photo: Lt. Gov. Gavin Newsom speaks during his inauguration ceremony on Jan. 10, 2011, at the state Capitol. (Hector Amezcua/The Sacramento Bee)