Persona?

I know that your company sells the same monitor in Europe, programmed for pregnancy avoidance, as Persona. Could you please tell me why this product is not sold in the U.S.? I know that a partial answer is "it's not FDA approved", but I'd really like to know why not: has the FDA refused to approve it? Do they categorically refuse to approve such products? Is the process of approval too difficult? (And, if so, exactly how difficult is it specifically, relative to the approval process in Europe?) Or has the company simply never wished to attempt approval?

thank you!