Johnston's rep confirmed that he and his girlfriend of a year, Sunny Oglesby, are expecting a child. Oglesby is a 20-year-old teacher in Johnston's hometown of Wasilla, Alaska.
The 21-year-old has his first child with Palin in late 2008. They were engaged twice, but the couple finally called it quits in October 2010.
Johnston and Oglesby have been dating since December 2010.