Editing Calendar-based contraceptive methods (section)

{{short description|Methods of estimating a woman's fertility}}
'''Calendar-based methods''' are various methods of estimating a [[woman]]'s likelihood of [[fertility]], based on a record of the length of previous [[menstrual cycle]]s. Various methods are known as the '''Knaus–Ogino method''' and the '''rhythm method'''. The '''standard days method''' is also considered a calendar-based method, because when using it, a woman tracks the days of her menstrual cycle without observing her physical fertility signs.  The standard days method is based on a fixed formula taking into consideration the timing of ovulation, the functional life of the sperm and the ovum, and the resulting likelihood of pregnancy on particular days of the menstrual cycle.  These methods may be used to achieve [[pregnancy]] by timing unprotected intercourse for days identified as fertile, or to [[birth control|avoid pregnancy]] by avoiding unprotected intercourse during fertile days.

The first formalized calendar-based method was developed in 1930 by John Smulders, a [[Catholic Church|Catholic]] physician from the [[Netherlands]]. It was based on knowledge of the [[menstrual cycle]]. This method was independently discovered by Hermann Knaus (Austria), and [[Kyusaku Ogino]] (Japan). This system was a main form of birth control available to Catholic couples for several decades, until the popularization of symptoms-based [[fertility awareness]] methods. A new development in calendar-based methods occurred in 2002, when [[Georgetown University]] introduced the Standard Days Method. The Standard Days Method is promoted in conjunction with a product called CycleBeads, a ring of colored beads which are meant to help the user keep track of her fertile and non-fertile days.