The 38-year-old, who is known for her wild antics and former drug-use, is forgoing her old party lifestyle because she plans to have a second child with 'The Kills' guitarist, reported Daily Mail online.
"Kate has made no secret among her circle that she'd love to have a baby with Jamie. There's no doubt that the prospect of another child is a massive motivation for her to clean up her act. She eats like a horse now, too, while back in her catwalk days she could easily forget to have lunch and dinner," a source said.
Moss wed Hince in July 2011 and the pair live in London's leafy Highgate area with her nine-year-old daughter Lila Grace from a previous relationship.
The star has recently been spotted holidaying in Saint Tropez where she enjoyed family-friendly activities with Lila and her rocker husband, who is reportedly very keen to experience parenthood with Moss.
"Jamie worships the ground she walks on, so to have the kind of bond that comes from parenthood would mean the world to him. Clearly it's not a straightforward process - neither of them are spring chickens.
"But it's what they want more than anything else. She's still Kate, but she's somehow different," the source added.