Inconceivable (Update); New Year, New You

Carolyn and Sean Savage hoped to have another child using embryos left over from the in vitro fertilization procedure that brought them their daughter. Ten days after the embryos were transferred into Carolyn, their doctor called with stunning news - she was implanted with someone else's embryos. "Dateline" visits the Savages once again, after their lives took yet another unexpected turn. In New Year, New You: Al Roker and his family open up about their plans to stay healthy in 2013; Natalie Morales follows two women who embark on a ten day digital detox; Interviews with Dr. Oz and Usher.