Natural family planning (NFP) comprises the family planning methods approved by the Roman Catholic Church and some Protestant denominations for both achieving and postponing or avoiding pregnancy. In accordance with the Church’s teachings regarding sexual behavior, NFP excludes the use of other methods of birth control, which it refers to as “artificial contraception
Periodic abstinence is now deemed moral by the Church for avoiding or postponing pregnancy for just reasons. When used to avoid pregnancy, couples may engage in sexual intercourse during a woman’s naturally occurring infertile times such as during portions of her ovulatory cycle. Various methods may be used to identify whether a woman is likely to be fertile; this information may be used in attempts to either avoid or achieve pregnancy.
Effectiveness can vary widely, depending on the method used, whether the user was trained properly, and how carefully they followed the protocol. Pregnancy can result in anywhere from 1 to 25% of the user population per year for users of the symptoms based or calendar based methods, depending on the method used and how carefully it was practiced. If perfectly practised, pregnancy rates can be as low as 1% per year; if imperfectly practised, as high as 25%. (See sidebar.)
Natural family planning has shown very weak and contradictory results in pre-selecting the gender of a child, with the exception of a Nigerian study at odds with all other findings. Because of these remarkable results, an independent study needs to be repeated in other populations.