Maci Bookout shared a first photo of her baby bump on Saturday.

The 23-year-old "Teen Mom" star took to Instagram to post a picture of herself with her puppy, Bonnie. Bookout is currently expecting her first child with boyfriend Taylor McKinney, and her growing belly is visible in the snapshot.

"Ridin' shotgun on our family fieldtrip!" she captioned the photo. "#nashville #arenacross."

Bookout is already mother to 6-year-old son Bentley with ex-fiance Ryan Edwards.

The reality star is diagnosed with polycystic ovary syndrome, and didn't think another pregnancy was possible. She and McKinney revealed they are expecting in December 2014.

Bookout came to fame on MTV reality series "16 and Pregnant," and subsequently appeared on four seasons of "Teen Mom."

She and original stars Catelynn Lowell and Amber Portwood will return for a fifth season later this year.