A source tells the website, "Their whole family was around to support them. 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 would do anything for Ashlee and now this baby girl. Ashlee is doing great and can't wait to get home to be with her family."
The child is Simpson's second - she is also a mum to six-year-old son Bronx, from her first marriage to rocker Pete Wentz.
Simpson and Ross wed in August, 2014.