Chelsea Houska's "sweet baby girl" has arrived -- and the mother-daughter duo share a birthday!

The Teen Mom 2 star and hubby Cole DeBoer welcomed daughter Layne, the MTV stars happily revealed. Aubree and Watson have a brand-new sibling -- and August 29 is a day for multiple celebrations in the DeBoer household.

"Happy birthday to YOU, sweet baby Layne," Chelsea captioned the sweet snapshot of her brand-new mini-me. Cole shared the same snapshot of the newborn (what a hat!) and wrote "Happy birthday to my sweet perfect wife Chelsea DeBoer @chelseahouska who just gave our family this beautiful blessing! Sharing the same amazing day I am so in love with our family! Our newest edition Baby Layne!!"

The couple announced that they were expecting back in March with matching Instagram sonogram images of their little lady; Chelsea gushed that everyone "could not be more excited," while Cole added he was "getting a new bow and it’s nailed my heart" (the reveal photo featured a bow). Soon after, Chelsea debuted her "wittle bump" and said " oh hey" to her mini-me. Now, Baby Layne is here -- and ready for plenty of "cheesy potatoes" photo ops with her big sis and bro!

Offer your congrats to the DeBoer family in the comments -- and be sure to keep watching Teen Mom 2 specials every Monday at 9/8c.