The 30-year-old actress fuelled pregnancy rumours when she was recently spotted attending a prenatal yoga class in LA, reported E!Online.
"This is something they both wanted. They are both so happy," a source said.
The 'That 70s Show' actress has been the subject of pregnancy speculations ever since she apparently got engaged to Kutcher last month.
"Ashton has been very private and cut off more than he usually is, he's very happy," the source added.