How do you not get pregnant the natural way?

No sex a week before and during her ovulation. Someone wrote wash after sex, pee etc but those things do not work. You can only get pregnant when you ovulate and sperm can live inside a woman for a week so timing is important. Once he ejaculates inside you there is no way to get it out and urinating wont help much since there is always new pre-ejaculate that also contains sperm as well as the ejaculation.