Natural family planning (NFP), which involves tracking fertility signs to plan or prevent pregnancy, has a wide range of effectiveness depending on how correctly it is used and the specific method.
- With typical use (average), NFP is about 76% to 88% effective in preventing pregnancy. This means that 12 to 24 out of 100 women might get pregnant in a year using NFP without perfect adherence.
- With perfect use (strict and accurate adherence), the effectiveness can be as high as 98% or more, especially with methods like symptothermal, lactational amenorrhea method, or combined fertility awareness techniques.
- Methods differ in effectiveness:
- Basal Body Temperature method: 75-88% effective typical use.
- Cervical Mucus method: 77-88% effective typical use.
- Calendar (rhythm) method: about 76% effective typical use, less reliable with irregular cycles.
- Symptothermal method: up to 98% effective with perfect use.
- Lactational amenorrhea method (exclusive breastfeeding postpartum): about 98-99% effective if criteria are strictly followed.
NFP does not protect against sexually transmitted infections, so barrier methods are recommended for STI prevention alongside NFP. In summary, natural family planning can be a reliable family planning option especially when methods are followed carefully, but it requires daily attention, commitment, and knowledge of fertility signs. It is less effective with typical use compared to hormonal or barrier contraceptives but offers benefits like being hormone-free and low-cost.
