"The first time I was here, I was pregnant and no one knew it," the 27-year-old actress told DeGeneres. "And then the second time, I just had my baby, but I got pregnant. So you're like a fertility good luck charm. If you want to get pregnant, come see Ellen."
"My show is an aphrodisiac," DeGeneres joked.
Fox also shared private photos of her two sons, Noah and Bodhi, for the first time. The Teenage Mutant Ninja Turtles actress and her husband, Brian Austin Green, welcomed Bodhi in February.
"Bodhi is the little chubby one and then Noah is the one with the lips," she explained.