Bristol Palin caused a stir when, at the age of 17, she announced she was pregnant and engaged to the baby's dad, Levi Johnston, at the 2008 Republican National Convention. "[I was thinking], 'Great, I'm 17 years old, I'm 40 pounds overweight with a big belly on me, all my friends are at school watching this on the news,'" she told Harper's Bazaar. Still, she added, her precious son Tripp was worth all the hardship. "I love my baby more than anything." J. Michael Arnoldi/BuzzFoto/FilmMagic.com - September 18, 2010
Michael Arnoldi/BuzzFoto
On the occasion of Bristol Palin's 21st birthday, omg! looks back at other celebs who started their families early.