The million dollar question. Each of the NFP methods has undergone multiple studies that have proven its method effectiveness to be above 90% and comparable to hormonal contraceptives.Here is some info on each method:


Billings: Method effectiveness- 99.5% Source
Creighton: Method effectiveness- 99.5% with a use effectiveness of 96.8% Source
Marquette: Method effectiveness- 99.4.% Source
Symptothermal Method: Method effectiveness-99.6% with a use effectiveness of 98.2% Source
Combined Oral Contraceptive Pill: Method effectiveness- 99.8% with a use effectiveness between 92-98% Source
Condoms: Method effectiveness- 98% with a use effectiveness of 82% Source


I added the last two just for comparison. NFP is just as or more effective than typical contraceptives. Also an important difference between using NFP and using contraception is that a couple using NFP almost always knows when they are taking a chance. Couples using contraception have been sold a false bill of goods. One that says if they’re ‘smart’ they’ll use protection and a pregnancy won’t occur. True empowerment is full knowledge and being able to act accordingly.
NFP doesn’t just work for postponing pregnancy. Charting helps a couple trying to get pregnant recognize their most fertile windows take advantage of these optimal times. It can also help a woman recognize irregularities in cycle and help her physician diagnose her specific problem. Because of this customization, it has been proven more effective at achieving a pregnancy than IVF. Source

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