The trio came to fame as teenagers on 16 and Pregnant in 2009, and continued their journey into motherhood on Teen Mom in 2012. Teen Mom aired for four seasons on MTV, and fourth castmate Farrah Abraham will not return for the new season.
Bookout is excited to introduce viewers to her boyfriend of two years, Taylor McKinney, and told Us Weekly she and 5-year-old son Bentley have both matured.
"My family and I are in such a new and interesting place in our lives," she shared. "I feel like I have grown up so much since the last time that I filmed anything for TV, so it will be very interesting to show viewers how our lives have evolved."
Portwood echoed Bookout's sentiments, and said she has "changed so much that [her] focus and goals are different than before." The reality star spent 17 months in prison for drug possession before being released in November 2013, and has written a book called Never Too Late for release August 26. Her daughter, Leah, is also 5 years old.
The new season will document Lowell's second pregnancy; she is currently pregnant with fiancé Tyler Baltierra. The young couple gave their first child, daughter Carly, up for adoption in season one of Teen Mom.
"I feel like documenting this pregnancy is totally different, because now it's our time to be parents," Lowell told the magazine. "Now people can see what it will be like to juggle the responsibilities of taking care of our new baby while navigating our relationship with Carly and her adoptive parents."
Teen Mom will return on MTV in 2015.