Sean Preston's Big First Year!

Britney and Kevin's firstborn turns 1 today – and what a year it's been! Check out the little tot's biggest moments. By Brian Orloff and Cara Lynn Shultz

BIG BROTHER

He's only 1, but he's already an older brother: Britney, who announced that she was pregnant again on The Late Show with David Letterman on May 9 (left), welcomed her second son on Sept. 12 – just two days shy of Sean's birthday, and four days before her second wedding anniversary. "It's going to be weird," she tells PEOPLE of the timing. "But I love it."