Natural Family Planning (NFP) is not based on folktales!
NFP is a general title for the methods of family planning that are science-based, accurate, natural, healthy, reliable, and moral. There are many NFP methods and all can be used to achieve, or to postpone, a pregnancy naturally.
NFP is based on scientific research about women's cycles of fertility. Over a century ago, scientists discovered cyclic changes in cervical mucus and their relation to ovulation. In the 1920s, scientists identified the temperature rise that signals ovulation. But it wasn't until the 1950s, that scientists developed programs to teach others how to observe and interpret these fertility signs.
NFP methods are grouped according to which signs of fertility are being observed and charted. They are as follows: the basal body temperature method (BBT) monitors changes in a woman's temperature when she wakes up each morning; the cervical mucus method ( more commonly called "Ovulation Method" or "OM") monitors changes in a woman's cervical mucus; the Sympto-Thermal Method (STM) combines observations of temperature and cervical mucus with other indicators, such as changes in the cervix and secondary fertility signs; and the Sympto-Hormonal Method (SHM), which is similar to the STM, includes the self-detection of reproductive hormones in the urine with the assistance of an ovulation predictor kit or fertility monitor.