The 25-year-old actress is expecting her first child with husband Brian Austin Green, reported Showbizpy.
"She's been helping to raise Brian's 10-year-old son Kassius for years, and now she'll have the experience of being mommy to a little girl. Obviously, Megan and Brian would be happy with a healthy baby of either gender, but they're beyond thrilled that Kassius is going to have a little sister," a source said.
"She'll be due at the very end of September or the first week in October. Megan is attached to a movie called 'Swindle', but it's in rewrites and probably won't even begin filming until next year. So right now her plate is totally clean, and she can devote herself to her baby," the source added.