Jamie Lynn Spears gave birth to a baby girl Thursday morning at a south Mississippi hospital, according to a friend of the Spears family. The friend, who asked not to be identified because the family had not yet announced the baby's birth, told The Associated Press that the baby was named Maddie Briann and weighed 7 pounds, 11 ounces. The 17-year-old Jamie Lynn was the star of Nickelodeon's "Zoey 101," a sitcom about prep school friends, and is the younger sister of pop star Britney Spears. The Spears family announced in December that Jamie Lynn was pregnant. The father is Casey Aldridge, a pipe-layer from Liberty, Miss. The couple is not married but announced an engagement several months ago.