New York City ? Sarah Palin says she didn’t know her daughter Bristol was sexually active before she learned the teenager was pregnant.

The former vice presidential candidate told ABC’s Barbara Walters: “Truthfully, we were devastated.”

Bristol was a high school senior when she gave birth to son Tripp in December. Her pregnancy was publicly announced just after Sarah Palin accepted John McCain’s invitation to be his running mate.

ABC released that exchange between Walters and Palin on Saturday. Portions of their interview begin airing Tuesday on “Good Morning America” and will be shown at length Friday on “20/20”. Palin is promoting her new book, “Going Rogue.”