Bristol Palin is reportedly joining the cast of "Teen Mom OG." TMZ reported Thursday the 27-year-old mother-of-three will star in the new season of the MTV reality series, which returns in the fall. Deadline confirmed Palin will join Amber Portwood, Maci Bookout and Catelynn Lowell as a new series regular on "Teen Mom OG." The former "Bristol Palin: Life's a Tripp" star and two-time "Dancing with the Stars" contestant's casting follows the exit of original "Teen Mom OG" cast member Farrah Abraham. Palin was 17 when she gave birth to her first child, son Tripp, with Levi Johnston. She is also parent to two daughters, 2-year-old Sailor and 14-month-old Atlee, with Dakota Meyer, and shared a photo of her three kids this week. Palin reflected on her pregnancy as a teen in an Instagram post in May. "10 years ago this week - my life took the biggest possible turn.. I was 17 and a junior in high school," the star wrote. "I am so thankful for God's plan over our life, and His grace that has covered us entirely.. my kids truly are my biggest blessing #purpose," she added. Palin filed for divorce from Meyer in January after less than two years of marriage, but has since appeared to reconcile with the Marines veteran. She showed off flowers from her estranged husband in May. Palin competed on the eleventh season of Dancing with the Stars in 2010 and reached the finals with pro partner Mark Ballas, finishing in third place. In November of that year, she also appeared on TLC's "Sarah Palin's Alaska" documentary.The daughter of Sarah Palin then starred in "Bristol Palin: Life's a Tripp" reality series on Lifetime in Summer 2012. She most recently competed on "Dancing with the Stars'" Fall 2012 All-Stars edition, where she was sent home in the fourth week of the Season 15 competition.