Fox, 27, and Green, 40, who wed in June 2010, are already parents to son Noah, 17 months. (Green is also dad to son Kassius, 11, with ex-girlfriend Vanessa Marcil.)
The This Is 40 actress admitted back in November that her second pregnancy was "rough in the beginning." "I've had rough first trimesters," the mom explained to Us of both her pregnancies. "But once you get into the second, it's fine after that."
Shortly after the announcement, former "Beverly Hills, 90210" star Green admitted that they didn't have their hearts set on a boy or a girl. "I'm [just] hoping for a healthy baby," he said. Adding about his pregnant wife: "She's doing great. She did great the first time around, but I wouldn't wish the experience on anybody! I couldn't do it! I couldn't make a baby, it's unbelievable!"
Keep clicking for more photos of the pretty pair ...