Ke$ha, Madonna & Miley Cyrus on stage at the 2013 Billboard Music Awards. (Getty)

Moments after Jace Evans' birthday on Aug. 2, 2009 (Courtesy of MTV)

Jenelle Evans and her son Jace during the 'Teen Mom 2' season 1 reunion. (Courtesy of MTV)

Jenelle and Jace (Splashnews)

Jenelle, her mom Barbara and Jace in a picture Jenelle posted to Twitter on May 9. (Courtesy of Twitter)

Ali and Aleeah Simms moments after they were born on Dec. 16, 2009. (Courtesy of MTV)

Leah Calvert with babies Ali (left) and Aleeah. (Courtesy of MTV)

Leah with her second husband Jeremy Calvert with Aleeah (left) and Ali Simms. (Courtesy of MTV)

Kailyn Lowry days after baby Isaac Rivera was born in January 2010. (Courtesy of MTV)

Kailyn Lowry with baby Isaac. (Courtesy of MTV)

Kailyn with Isaac, now three years old. (Splashnews)

Chelsea Houska's daughter Aubree. (Courtesy of MTV)

Chelsea and Aubree. (Courtesy of Twitter)

Aubree Houska, now three, in a Twitpic posted by Chelsea. (Courtesy of Twitter)

Oxbow and his jockey, Gary Stevens, racing in the 2013 Preakness Stakes. (Getty)

Oxbow and his jockey, Gary Stevens, racing in the 2013 Preakness Stakes. (Getty)

Oxbow and his jockey, Gary Stevens, racing in the 2013 Preakness Stakes. (Getty)

Oxbow and his jockey, Gary Stevens, racing in the 2013 Preakness Stakes. (Getty)

Oxbow and his jockey, Gary Stevens, racing in the 2013 Preakness Stakes. (Getty)

Oxbow and his jockey, Gary Stevens, racing in the 2013 Preakness Stakes. (Getty)