Fertility awareness

Fertility awareness (FA) refers to a set of practices used to determine the fertile and infertile phases of a woman's menstrual cycle. Fertility awareness methods may be used to avoid pregnancy, to achieve pregnancy, or as a way to monitor gynecological health.

Methods of identifying infertile days have been known since antiquity, but scientific knowledge gained during the past century has increased the number, variety, and especially accuracy of methods.

Systems of fertility awareness rely on observation of changes in one or more of the primary fertility signs (basal body temperature, cervical mucus, and cervical position), tracking menstrual cycle length and identifying the fertile window based on this information, or both. Other signs may also be observed: these include breast tenderness and mittelschmerz (ovulation pains), urine analysis strips known as ovulation predictor kits (OPKs), and microscopic examination of saliva or cervical fluid. Also available are computerized fertility monitors.

Symptoms-based methods involve tracking one or more of the three primary fertility signs: basal body temperature, cervical mucus, and cervical position. Systems relying exclusively on cervical mucus include the Billings Ovulation Method, the Creighton Model, and the Two-Day Method. Symptothermal methods combine observations of basal body temperature (BBT), cervical mucus, and sometimes cervical position. Calendar-based methods rely on tracking a woman's cycle and identifying her fertile window based on the lengths of her cycles. The best known of these methods is the Standard Days Method. The Calendar-Rhythm method is also considered a calendar-based method, though it is not well defined and has many different meanings to different people.

Systems of fertility awareness may be referred to as fertility awareness–based methods; the term Fertility Awareness Method (FAM) refers specifically to the system taught by Toni Weschler. The term natural family planning is sometimes used to refer to any use of fertility awareness methods, the lactational amenorrhea method and periodic abstinence during fertile times. A method of fertility awareness may be used by natural family planning users to identify these fertile times.

Women who are breastfeeding a child and wish to avoid pregnancy may be able to practice the lactational amenorrhea method. The lactational amenorrhea method is distinct from fertility awareness, but because it also does not involve contraceptives, it is often presented alongside fertility awareness^{[by whom?]} as a method of "natural" birth control.

Within the Catholic Church and some Protestant denominations, the term natural family planning is often used to refer to Fertility Awareness pointing out it is the only method of family planning approved by the Church.

It is not known exactly when it was first discovered that women have predictable periods of fertility and infertility. It is already clearly stated in the Talmud tractate Niddah, that a woman only becomes pregnant in specific periods in the month, which seemingly refers to ovulation. St. Augustine wrote about periodic abstinence to avoid pregnancy in the year 388 (the Manichaeans attempted to use this method to remain childfree, and Augustine condemned their use of periodic abstinence). One book states that periodic abstinence was recommended "by a few secular thinkers since the mid-nineteenth century," but the dominant force in the twentieth century popularization of fertility awareness-based methods was the Roman Catholic Church.