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Jamie Lynn Spears Has a Baby Girl

By Mary Margaret

06/19/2008 at 11:35 AM EDT

There is a new baby in the Spears clan! Jamie Lynn Spears and her fiancé Casey Aldridge welcomed a baby girl Thursday morning.

PEOPLE confirms exclusively that the baby was named Maddie Briann.

"Just the family was there," says a source about the birth around 9:30 a.m. at a hospital in Mississippi, near her Louisiana hometown. "Everyone is healthy and happy."

Jamie Lynn's sister Britney, father Jamie and brother Bryan flew in Wednesday to be with her for the birth; her mother Lynne had been with her helping her get ready for the baby.

Since announcing her pregnancy in December, Britney’s little sister has retreated from the bright lights of Hollywood, opting for the comforts of her hometown of Kentwood, La.

With her Nickelodeon show Zoey 101 already ended, Jamie Lynn went home to prepare for the birth of her baby. The actress, 17, and Aldridge, 19, got engaged in March. Recently, the couple purchased a three-bedroom home in Liberty, Miss., where Aldridge went to high school.

Over the last few months, Spears has kept busy by passing her GED exam, preparing the nursery and attending multiple baby showers.

Jamie Lynn's Zoey 101 costar, Erin Sanders, told PEOPLE earlier this year that the actress will be a fun mother.

"She is just a very good-hearted and warm person," he said. "We would always hang out on the set and she is a lot of fun, so I think she's going to be an easygoing, fun mom."

More Celeb Baby Boom: Proud parents – Nicole Richie, Christina Aguilera, Angelina Jolie and more – show off their adorable additions on the cover of PEOPLE