NEW YORK — Gillian Anderson and her boyfriend, Mark Griffiths, are expecting their second child this fall, her manager, Connie Freiberg, said Wednesday.

The “X-Files” actress and the businessman have an 18-month-old son, Oscar.

Anderson, 39, has a 13-year-old daughter, Piper, with ex-husband Clyde Klotz, a production designer. She and her second husband, documentary filmmaker Julian Ozanne, separated in April 2006 after 16 months of marriage.

Anderson reunites with co-star David Duchovny for “The X-Files: I Want to Believe,” the second feature film spun off from the paranormal series. The movie will be in theaters July 25.