For four seasons fans of "Teen Mom" watched Maci, Amber and Catelynn face multiple challenges in their first years of motherhood, including such things as graduating from high school, relationships, getting jobs, beginning college and moving out on their own. Oh, and raising their first child. Now the original girls -- hence, the "OG" in the revived series title -- return to reveal the challenges of raising children on camera, and how life in the public eye has shaped them as parents and people. It's an unprecedented view of young mothers facing the responsibilities of parenthood as their children enter kindergarten, start little league and reach other milestones of youth.