The actor, who reprises his role as Iron Man in the upcoming movie The Avengers, and his wife of six years are set to welcome their first child together early next year.
“Robert and Susan could not be more excited over this news,” his rep tells PEOPLE. “They can’t wait to welcome this new baby into their wonderful family.”
The actor, 46, is already a father to Indio, 17, his son with ex-wife Deborah Falconer.
But the news should come as no surprise. In 2010, while promoting his comedy Due Date, Downey predicted he’d have another kid in 2012.
“I think I will be wrist-deep in doo-doo within 18 months. I’m calling it right here,” he said.
And he was thinking pink.
“I think we should probably try to have a girl because I don’t want another male entity to have to compete,” he said. “I don’t want Indio to feel there’s another boy in my life. But I don’t know what we’d have to do [to have a girl]. Do we have to put it in a spoon and hang it upside-down?”