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 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!' 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.'