Jason Clarke and Cecile Breccia are expecting a second son.
Clarke kept an arm around a visibly pregnant Breccia as they attended the 2018 Screen Actors Guild Awards on Sunday.
The actress showed off her baby bump in a formfitting lace gown with a plunging neckline.
People reported Clarke and Breccia already share a 3-year-old son.
Clarke's movie "Mudbound" was nominated for Outstanding Performance by a Cast in a Motion Picture at the awards show, but lost to "Three Billboards Outside Ebbing, Missouri."
"Dee [Rees] directed an amazing film with an eclectic cast," the actor said of "Mudbound" in an interview with E! News on the red carpet.
"Mudbound" is based on the Hillary Jordan novel of the same name.
The film co-stars Carey Mulligan, Jason Mitchell and Mary J. Blige, and opened in theaters in November.