Ashlee Simpson and Evan Ross have finally welcomed their love child. On July 30, Simpson gave birth to the couple's first baby together, a daughter, E! News reports. The baby girl joins 6-year-old big brother Bronx Mowgli Wentz, Simpson's son from her first marriage to rocker Pete Wentz. "Their whole family was around to support them," a source told E! of last night's delivery. "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." Simpson and Ross announced they were expecting in December, just a few months after getting married in August. Their star-studded extended family includes Ross' mother, singer Diana Ross, and Simpson's sister, Jessica Simpson. In other words, baby girl (whose name has yet to be revealed) has some serious lullabies coming her way.