The baby girl is the second child for the 30-year-old "Pieces of Me" singer -- she shares her 6-year-old son Bronx Mowgli with her ex-husband, Fall Out Boy bassist Pete Wentz -- and the first for Ross, 26. The two got engaged in January 2014 after six months of dating and were married in a small Connecticut ceremony last August.
Bronx, who is already big brother to Wentz's 11-month-old son Saint Lazslo with girlfriend Meagan Camper, is reportedly very happy about the new addition. "I told him pretty early on," Simpson told People in February. "And he wanted to have a sister, so he’s really excited!"
The Simpson-Ross clan is already one adorable bunch, so we can't wait to see the first family photo with their new baby girl!
Check out the other celebrity baby announcements that should be coming this summer: