"Baby.......GIRL!!!!!!" Chelsea captioned the snapshot above of the clan reacting to pink confetti, courtesy of some gender reveal confetti cannons.
The new bundle of joy -- who joins older sibs Aubree, Watson and Layne -- will arrive in "early 2021," and Chelsea gushed "everything’s been going very smooth, and baby is doing good." The sweet pregnancy announcement came via a list of every family member's name written in their soon-to-be home -- and it included "baby" with a little accompanying heart.
MTV News will have Baby DeBoer updates, as well as coverage around the brand-new season of Teen Mom 2 premiering on September 1 (a supersized sneak peek is below).