The newlyweds have been excitedly awaiting the arrival of their little one ever since they announced the happy news that they were having a girl in February.
"Their whole family was around to support them," a source told E! News of their baby's birth. "Evan was very emotional and loves Ashlee so much. He did not leave her side and wanted to go through this with her every step of the way. He can't wait to be a dad. He would do anything for Ashlee and now this baby girl. Ashlee is doing great and can't wait to get home to to be with her family."
The new parents aren't the only two excited about the littlest Simpson-Ross. Ashlee's six-year-old son from her marriage to Pete Wenz, Bronx, couldn't be more thrilled to have a little sister. "I told him pretty early on," Simpson told Us Weekly of Bronx once they found out they were having a girl. "He wanted to have a sister, so he's really excited! He's got a little brother. Now he's going to have a little sister!"
Ashlee and Evan both promised a unique name, which, Ross promised: "You guys will figure out the story behind it once we tell the name," he said to People in June.
While this is his first child, Ross has already earned some parenting stripes while taking care of Bronx. "It's amazing. I can't even tell you how incredible that child is — he's unbelievable!" Ross has previously told People of Bronx. "He's been a blessing in my life and I've learned so much from him."