Pete Wentz
is adding to his brood!

The "Fall Out Boy" rocker shared an adorable snapshot on Instagram Monday, announcing that he's expecting his first child with his girlfriend Meagan Camper.

In the pic, Wentz and Camper are sharing a kiss as he places his hand over her belly.

During a recent interview on "The Wendy Williams Show," the 34-year-old opened up about his relationship of nearly three years, saying, "I feel really lucky. It's, like, really interesting [to be] in a relationship with someone who is truly my best friend. Like, I talk to her about everything. She will tell me when I'm being not so insane, and sometimes she's like, 'You're being a little bit insane.' It's very helpful."

Wentz has 5-year-old son Bronx with newly-engaged ex-wife Ashlee Simpson, and this will be Meagan's first child.

Congrats to the happy couple! 

Are you surprised by the pregnancy news? Sound off below, and click "Launch Gallery" above to see more expecting celebrities.