Along with her announcement, she made it clear in her tweet she was also politically ready for a girl, disagreeing with Donald Trump's previous comments about females and body image.
"As someone who is about to have a daughter, this hits me deep in my core," Wilde wrote. "#NeverTrump."
Wilde was seen recently showing off her baby bump in New York City wearing adorable denim overalls, a white tank top and white converse shoes.
As for becoming a big brother, her son Otis' reaction is super cute.