Sarah Palin said she was "shocked" to learn her teenage daughter Bristol was sexually active upon learning her daughter, Bristol-- then a 17-year-old high school student -- was pregnant last year.
"That's why I was shocked," the former governor of Alaska told Barbara Walters in an ABC interview that will air in installments this week. "Truthfully, we were devastated."
Her daughter's pregnancy was announced just after Palin became the vice-presidential nominee for the Republican party last year; Bristol gave birth to her to son, Tripp Easton Mitchell, on December 27, 2008.
The baby's father, Playgirl magazine beefcake Levi Johnston, told The Tyra Banks Show last spring that Palin was well aware him and her teen daughter were having sex under her roof.
"I'm pretty sure she probably knew," Johnston said. "Moms are pretty smart."
Palin's new book, Going Rogue, is in stores now.