Jessica Simpson 'ecstatic' following birth of son

Jessica Simpson is "ecstatic" following the birth of her son on Sunday.

The 'Fashion Star' mentor, who also has a daughter Maxwell, 14 months, with her fiancé Eric Johnson, is "so happy" to have finally welcomed her son, Ace Knute, into the world. 

A source close to the singer turned fashion designer, 32, told UsMagazine.com that the couple "are so happy to have a boy. One of each, everybody wants that.

"The baby is beautiful. He has Eric's little chin dimple!" 

Simpson's daughter Maxwell is also very excited to be a big sister.

The friend explained: "Maxwell is excited. She doesn't totally get it and understand, but she is very excited to have a brother."

The singer has had plenty of visitors in hospital since the birth, including her parents Tina and Joe, sister Ashlee, 28, and pregnant best friend Cacee Cobb.

Joe also tweeted: "Very blessed to celebrate the birth of my new grandson."

Simpson, who was previously married to Nick Lachey, gave birth via a scheduled C-section in Los Angeles.

The blonde beauty is expected to resume her position as a Weight Watchers spokesperson later this summer.