Kristen Bell gave birth to a baby girl ! Dax Shepard announced the news on Twitter today, writing, "Lincoln Bell Shepard is here. She has mom's beauty and dad's obsession with breasts. Hooray!" Kristen later tweeted her own message: "My new roomate poops her pants and doesn't pay rent...basically Dax Shepard pre-sobriety. Welcome baby Lincoln xo." Congrats to the new family of three!