The 29-year-old first-time mom is expecting a child with fiancé Romain Dauriac.
Johansson and Dauriac, a former French journalist, first went public about their relationship in November 2012 and got engaged in August 2013. Johansson told The Daily Mail in December 2013 that the two lead a "normal domestic life in Paris," and that "I would like to have my own family, that would be nice."
Johansson most recently appeared as the voice for the character Samantha in Spike Jonze's Her. She will reprise her role as Natasha Romanoff (Black Widow) in the upcoming Captain America: The Winter Soldier and 2015's Avengers: Age of Ultron.