Jessica Simpson is ''ecstatic'' following the birth of her son on Sunday (30.06.13).

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 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!''

Jessica'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.''

Jessica 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.''

Jessica, 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.