Jennifer Lopez took 20 pregnancy tests before she would believe that she was with child, the Bronx, NY-born beauty says in the October issue of Elle Magazine.

“We knew nothing was wrong with either one of us—I had been checked, and he had kids already,” Jennifer explains of her Marc’s struggle to conceive. “I knew Something’s not ready here, in my head or in my life, and when it is, I know it’s going to happen.”

“I needed to see what a negative looked like,” says Max and Emme’s mom, who also admits to making hubby Marc Anthony pee on a stick.

“I was sitting down doing hair and makeup…And I felt a flutter — the weirdest little flourish. My makeup artist said, ‘What’s the matter?’ I didn’t say anything but in my head I was like, ‘I have life inside me!’”

Read more of Jennifer Lopez’ interview with Elle Magazine, on newsstands September 10.