The MTV star announced her happy news via an Instagram photo of her sporting a sizeable baby bump, telling fans: "Baby boy coming soon! #lastbutnotleast."
Does that hashtag mean she's stopping at three?!
This will be her second child with fiancé Taylor McKinney. They welcomed daughter Jayde last year. Maci's also mum to son Bentley, seven, from her relationship with childhood sweetheart Ryan Edwards.
Jayde shared a second sweet image to Instagram showing Jayde cuddled up on her stomach, writing: "Baby Jayde showing her little brother some love before bed. My heart is so full."
Maci found fame in MTV documentary 16 & Pregnant which charted her teenage pregnancy with Bentley. She also appeared in the spinoff Teen Mom.
Currently, she can be seen in MTV's Teen MomOG, which catches up with Maci, Amber Portwood, Catelynn Lovell and Farrah Abraham several years after the original series.
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