The actors, who have a 2-year-old son, Leonardo, are expecting their second child together, the New York Post's Page Six reports.
"Nature is very wise and gives you nine months to prepare, but in that moment – when you see that face, you are transformed forever," Cruz, 38, has said of parenthood.
Reps for the couple did not immediately respond to PEOPLE's requests for comment.
Cruz and Bardem, 43, both Oscar winners, were married in July 2010 at a friend's home in the Bahamas.
If true, this won't be the only new addition to the family this year – Cruz's sister Mónica is expecting a bundle of joy of her own.