The brunette beauty, 25, and actor hubby Brian Austin Green are expecting their first child, reports Radar Online. They tied the knot in 2010.
"They just found out and are incredibly excited," a source close to the couple told Star Magazine -- noting that the pregnancy was unexpected. "It's still early, so they are only telling close friends and family members."
Megan is stepmother to Brian's 10-year-old son with his ex, Vanessa Marcil.
The source added, "She has really grown in the past couple of years. Megan used to only be concerned with her career, but now family comes first."