Baby Bronx has turned Ashlee Simpson-Wentz into a hot mama…or was it that plastic surgeon?

The 24-year-old singing star, who welcomed son Bronx with hubby Pete Wentz last November, has already had her lips fatten with Restalyne injections and undergone laser surgery to zap away her stretch marks, Star Magazine has learned.

In addition, Ashlee is considering having liposuction.

“She looks like she never had a baby,” says a insider.