In 2009, MTV stumbled onto a phenomenon. 16 and Pregnant introduced the world to expectant teens, including Amber Portwood, Maci Bookout, Catelynn Lowell and Farrah Abraham, and by December of that year, the quartet was given their own show. Teen Mom debuted to an audience of 2.1 million, who watched as Catelynn, 27, and boyfriend Tyler Baltierra dealt with the aftermath of putting their daughter, Carly, up for adoption; Maci, 27, battled with then-fiancé Ryan Edwards (dad to her 10-year-old son, Bentley), who’s been in and out of jail and rehab; and Amber, 29, struggled with bipolar disorder while trying to parent daughter Leah, now 10, with then-fiancé Gary Shirley. It’s been a long, hard road for these women, and now they’re looking back on their journey with Us: Catelynn…