Chances are if you are a fan of 'Gossip Girl,' you know Kaylee DeFer as the devious Ivy Dickens. Now you can know her as the mom formerly known as Ivy Dickens.

DeFer welcomed her first child, a son, on Friday (Sept. 20) with her boyfriend Michael Fitzpatrick according to the rep for his band, Fitz & the Tantrums.

"Kaylee was a rock star!" the frontman told Us Weekly of his baby mama.

The couple named the baby Theodore Ignatius Fitzpatrick, which may be an even more serious name than Prince George Alexander Louis.

Fitzpatrick was supposed to play with his band on Friday, but plans changed when DeFer suddenly went into a labor. On their Facebook page, the band wrote, "Hey, San Diego, unfortunately we will not be playing at 91x fest today because FORTUNATELY there is a baby Fitz coming! Thank you so much for understanding. We hope to make it up to you all soon!"

After the birth, the group added to their Facebook page, "Congratulations to our partner in crime Fitz and our beautiful friend Kaylee on the birth of their beautiful son. The world has another superstar!!!"

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