How not to get pregnant without using protection (condoms, pills, rings, birth control), not using protection at all?

NFP. Natural family planning, ovulation method, creighton method these are all ways of predicting when you will ovulate so you can abstain from sex and hopefully not get pregnant. You can find instructions online, but if you really want to avoid pregnancy, going to a class would be a good idea. Tho only 100% effective way to not get pregnancy is to not have sex.