Calendar-based methods are various methods of estimating a
woman
A woman is an adult female human. Prior to adulthood, a female human is referred to as a girl (a female child or adolescent). The plural ''women'' is sometimes used in certain phrases such as "women's rights" to denote female humans regardl ...
's likelihood of
fertility
Fertility is the capability to produce offspring through reproduction following the onset of sexual maturity. The fertility rate is the average number of children born by a female during her lifetime and is quantified demographically. Fertili ...
, based on a record of the length of previous
menstrual cycle
The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that make pregnancy possible. The ovarian cycle controls the production and release of eggs a ...
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
Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins.
Pregnancy usually occurs by sexual intercourse, but ca ...
by timing unprotected intercourse for days identified as fertile, or to
avoid pregnancy by avoiding unprotected intercourse during fertile days.
The first formalized calendar-based method was developed in 1930 by John Smulders, a
Catholic
The Catholic Church, also known as the Roman Catholic Church, is the largest Christian church, with 1.3 billion baptized Catholics worldwide . It is among the world's oldest and largest international institutions, and has played a ...
physician from the
Netherlands
)
, anthem = ( en, "William of Nassau")
, image_map =
, map_caption =
, subdivision_type = Sovereign state
, subdivision_name = Kingdom of the Netherlands
, established_title = Before independence
, established_date = Spanish Netherl ...
. It was based on knowledge of the
menstrual cycle
The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that make pregnancy possible. The ovarian cycle controls the production and release of eggs a ...
. This method was independently discovered by Hermann Knaus (Austria), and
Kyusaku Ogino
was a Japanese medical doctor specializing in obstetrics and gynecology.
His natural father's family name was Nakamura, but Kyusaku was adopted by the Ogino family in 1901.
Ogino studied infertility and developed a method to estimate the ferti ...
(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
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 gynec ...
methods. A new development in calendar-based methods occurred in 2002, when
Georgetown University
Georgetown University is a private university, private research university in the Georgetown (Washington, D.C.), Georgetown neighborhood of Washington, D.C. Founded by Bishop John Carroll (archbishop of Baltimore), John Carroll in 1789 as Georg ...
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.
Terminology
While the terms ''rhythm method'' and ''fertility awareness'' are not synonymous, some sources do treat them as such. However,
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 gynec ...
is usually used as a broad term that includes tracking
basal body temperature
Basal body temperature (BBT or BTP) is the lowest body temperature attained during rest (usually during sleep). It is usually estimated by a temperature measurement immediately after awakening and before any physical activity has been undertaken. ...
and
cervical mucus
The cervix or cervix uteri (Latin, 'neck of the uterus') is the lower part of the uterus (womb) in the human female reproductive system. The cervix is usually 2 to 3 cm long (~1 inch) and roughly cylindrical in shape, which changes during ...
as well as cycle length. The
World Health Organization
The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of h ...
considers the rhythm method to be a specific type of calendar-based method, and calendar-based methods to be only one form of fertility awareness.
More effective than calendar-based methods, systems of fertility awareness that track basal body temperature, cervical mucus, or both, are known as symptoms-based methods. Teachers of symptoms-based methods take care to distance their systems from the poor reputation of the rhythm method. Many consider the rhythm method to have been obsolete for at least 20 years,
and some even exclude calendar-based methods from their definition of fertility awareness.
Some sources may treat the terms ''rhythm method'' and ''natural family planning'' as synonymous. In the early 20th century, the calendar-based method known as the ''rhythm method'' was promoted by members of the
Roman Catholic Church
The Catholic Church, also known as the Roman Catholic Church, is the largest Christian church, with 1.3 billion baptized Catholics worldwide . It is among the world's oldest and largest international institutions, and has played a ...
as the only morally acceptable form of
family planning
Family planning is the consideration of the number of children a person wishes to have, including the choice to have no children, and the age at which they wish to have them. Things that may play a role on family planning decisions include marita ...
. Methods accepted by this church are referred to as
natural family planning
Natural family planning (NFP) comprises the family planning methods approved by the Catholic Church and some Protestant denominations for both achieving and postponing or avoiding pregnancy. In accordance with the Church's teachings regarding s ...
(NFP): so at one time, the term "the rhythm method" was synonymous with NFP. Today, NFP is an umbrella term that includes symptoms-based fertility awareness methods and the
lactational amenorrhea method
Lactational amenorrhea, also called postpartum infertility, is the temporary postnatal infertility that occurs when a woman is amenorrheic (not menstruating) and fully breastfeeding.
Physiology
Hormonal pathways and neuroendocrine control
...
as well as calendar-based methods such as rhythm. This overlap between uses of the terms "the rhythm method" and "natural family planning" may contribute to confusion.
The first day of bleeding is considered day one of the menstrual cycle.
History
Early methods
It is not known if historical cultures were aware of what part of the menstrual cycle is most fertile. In the year 388,
Augustine of Hippo
Augustine of Hippo ( , ; la, Aurelius Augustinus Hipponensis; 13 November 354 – 28 August 430), also known as Saint Augustine, was a theologian and philosopher of Berber origin and the bishop of Hippo Regius in Numidia, Roman North Af ...
wrote of periodic abstinence. Addressing followers of
Manichaeism
Manichaeism (;
in New Persian ; ) is a former major religionR. van den Broek, Wouter J. Hanegraaff ''Gnosis and Hermeticism from Antiquity to Modern Times''SUNY Press, 1998 p. 37 founded in the 3rd century AD by the Parthian Empire, Parthian ...
, his former religion, he said, "Is it not you who used to counsel us to observe as much as possible the time when a woman, after her purification, is most likely to conceive, and to abstain from cohabitation at that time...?"
If the Manichaieans practiced something like the Jewish
observances of menstruation, then the "time... after her purification" would have indeed been when "a woman... is most likely to conceive."
Over a century previously, however, the influential
Greek physician Soranus had written that "the time directly before and after menstruation" was the most fertile part of a woman's cycle; this inaccuracy was repeated in the 6th century by the
Byzantine
The Byzantine Empire, also referred to as the Eastern Roman Empire or Byzantium, was the continuation of the Roman Empire primarily in its eastern provinces during Late Antiquity and the Middle Ages, when its capital city was Constantinopl ...
physician
Aëtius. Similarly, a
Chinese
Chinese can refer to:
* Something related to China
* Chinese people, people of Chinese nationality, citizenship, and/or ethnicity
**''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation
** List of ethnic groups in China, people of va ...
sex manual written close to the year 600 stated that only the first five days following menstruation were fertile.
Some historians believe that Augustine, too, incorrectly identified the days immediately after menstruation as the time of highest fertility.
Written references to a "safe period" do not appear again for over a thousand years.
Scientific advances prompted a number of secular thinkers to advocate periodic abstinence to avoid pregnancy:
in the 1840s it was discovered that many animals ovulate during
estrus
The estrous cycle (, originally ) is the set of recurring physiological changes that are induced by reproductive hormones in most mammalian therian females. Estrous cycles start after sexual maturity in females and are interrupted by anestrous p ...
. Because some animals (such as
dog
The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. Do ...
s) have a bloody discharge during estrus, it was assumed that menstruation was the corresponding most fertile time for women. This inaccurate theory was popularized by physicians
Bischoff
Bischoff is a surname. Notable people with the surname include:
* Amaury Bischoff, French-Portuguese footballer
* Anna Catharina Bischoff (1719–1787), wife of pastor Lucas Gernler
* Bernard J. Bischoff (1931–1980), American politician and j ...
,
Félix Archimède Pouchet
Félix-Archimède Pouchet (26 August 1800 – 6 December 1872) was a French naturalist and a leading proponent of spontaneous generation of life from non-living materials, and as such an opponent of Louis Pasteur's germ theory. He was the father ...
, and Adam Raciborski.
In 1854, an
English
English usually refers to:
* English language
* English people
English may also refer to:
Peoples, culture, and language
* ''English'', an adjective for something of, from, or related to England
** English national ide ...
physician named George Drysdale correctly taught his patients that the days near menstruation are the ''least'' fertile, but this remained the minority view for the remainder of the 19th century.
Knaus–Ogino or rhythm method
In 1905
Theodoor Hendrik van de Velde
Theodoor Hendrik van de Velde (12 February 1873, Leeuwarden – 27 April 1937 near Locarno in a plane crash) was a Dutch physician and gynæcologist who served as director at the Gynæcological Institute in Haarlem.
Biography
His 1926 book ...
, a Dutch gynecologist, showed that women only ovulate once per menstrual cycle. In the 1920s,
Kyusaku Ogino
was a Japanese medical doctor specializing in obstetrics and gynecology.
His natural father's family name was Nakamura, but Kyusaku was adopted by the Ogino family in 1901.
Ogino studied infertility and developed a method to estimate the ferti ...
, a Japanese gynecologist, and Hermann Knaus, from Austria, working independently, each made the discovery that ovulation occurs about fourteen days before the next menstrual period.
Ogino used his discovery to develop a formula for use in aiding infertile women to time intercourse to achieve pregnancy.
In 1930, Johannes Smulders, a
Roman Catholic
Roman or Romans most often refers to:
*Rome, the capital city of Italy
*Ancient Rome, Roman civilization from 8th century BC to 5th century AD
*Roman people, the people of ancient Rome
*'' Epistle to the Romans'', shortened to ''Romans'', a lette ...
physician from the Netherlands, used Knaus and Ogino's discoveries to create a method for ''avoiding'' pregnancy. Smulders published his work with the Dutch Roman Catholic medical association, and this was the official rhythm method promoted over the next several decades.
In 1932 a Catholic physician, Dr. Leo J Latz, published a book titled ''The Rhythm of Sterility and Fertility in Women'' describing the method,
and the 1930s also saw the first U.S. Rhythm Clinic (founded by
John Rock) to teach the method to Catholic couples.
Later 20th century to present
In the first half of the 20th century, most users of the rhythm method were Catholic; they were following their church's teaching that all other methods of birth control were sinful. In 1968 the encyclical ''
Humanae vitae
''Humanae vitae'' (Latin: ''Of Human Life'') is an encyclical written by Pope Paul VI and dated 25 July 1968. The text was issued at a Vatican press conference on 29 July. Subtitled ''On the Regulation of Birth'', it re-affirmed the teaching of ...
'' included the statement, "It is supremely desirable... that medical science should by the study of natural rhythms succeed in determining a sufficiently secure basis for the chaste limitation of offspring." This is interpreted as favoring the then-new, more reliable symptoms-based
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 gynec ...
methods over the rhythm method. Currently, many fertility awareness teachers consider the rhythm method to have been obsolete for at least 20 years.
New attention was drawn to calendar-based methods in 2002, when the Institute for Reproductive Health at
Georgetown University
Georgetown University is a private university, private research university in the Georgetown (Washington, D.C.), Georgetown neighborhood of Washington, D.C. Founded by Bishop John Carroll (archbishop of Baltimore), John Carroll in 1789 as Georg ...
introduced the Standard Days Method. Designed to be simpler to teach and use than the older rhythm method, the Standard Days Method is being successfully integrated into
family planning
Family planning is the consideration of the number of children a person wishes to have, including the choice to have no children, and the age at which they wish to have them. Things that may play a role on family planning decisions include marita ...
programs worldwide.
Types and effectiveness
Most menstrual cycles have several days at the beginning that are infertile (pre-ovulatory infertility), a period of fertility, and then several days just before the next menstruation that are infertile (post-ovulatory infertility). The first day of red bleeding is considered day one of the menstrual cycle. To use these methods, a woman is required to know the length of her menstrual cycles.
Imperfect use of calendar-based methods would consist of not correctly tracking the length of the woman's cycles, thus using the wrong numbers in the formula, or of having unprotected intercourse on an identified fertile day. The discipline required to keep accurate records of menstrual cycles, and to abstain from unprotected intercourse, makes imperfect use fairly common. The typical-use failure rate of calendar-based methods is 25% per year.
Rhythm method (Knaus–Ogino method)
To find the estimated length of the pre-ovulatory infertile phase, eighteen (18) is subtracted from the length of the woman's shortest cycle. To find the estimated start of the post-ovulatory infertile phase, eleven (11) is subtracted from the length of the woman's longest cycle.
A woman whose menstrual cycles ranged in length from 30 to 36 days would be estimated to be infertile for the first 11 days of her cycle (30-19=11), to be fertile on days 12–25, and to resume infertility on day 26 (36-10=26). When used to avoid pregnancy, such fertility awareness-based methods have a typical-use failure rate of 25% per year.
Standard Days Method
![Geburtenkontrollkette](https://upload.wikimedia.org/wikipedia/commons/e/ef/Geburtenkontrollkette.jpg)
Developed by
Georgetown University
Georgetown University is a private university, private research university in the Georgetown (Washington, D.C.), Georgetown neighborhood of Washington, D.C. Founded by Bishop John Carroll (archbishop of Baltimore), John Carroll in 1789 as Georg ...
's Institute for Reproductive Health, the Standard Days Method has a simpler rule set and is more effective than the rhythm method.
A product called
CycleBeads
CycleBeads is a visual tool that was developed by the Institute for Reproductive Health at Georgetown University. This device helps women use the Standard Days Method, a fertility awareness-based family planning method.
The Standard Days Method ...
was developed alongside the method to help the user keep track of estimated high and low fertility points during her menstrual cycle. The Standard Days Method may only be used by women whose cycles are usually between 26 and 32 days in length; it is estimated that between 50% and 60% of women of reproductive age satisfy this condition.
In this system:
* Days 1–7 of a woman's menstrual cycle are considered infertile
* Days 8–19 are considered fertile; considered unsafe for unprotected intercourse
* Day 20 through the end of the cycle are considered infertile.
When used to avoid pregnancy, the Standard Days Method has been estimated to have perfect-use efficacy of 95% and typical-use efficacy of 88%.
[Weis, Julianne; Festin, Mario (2020-02-07)]
«Implementation and Scale-Up of the Standard Days Method of Family Planning: A Landscape Analysis»
''Global Health: Science and Practice'' 8 (1): 114-124. . . These figures are based on a 2002 study in Bolivia, Peru, and the Philippines of women of reproductive age having menstrual cycles between 26 and 32 days,
and on a 2014 study in Turkey. However, other researchers have criticized the methodology of the first study, have stated that the 95% figure has been presented to the public in misleading ways, and have argued that the true efficacy figures are likely to be much lower.
Software-based systems
Several web-based implementations of the cycle method exist, as well as
mobile app
A mobile application or app is a computer program or software application designed to run on a mobile device such as a phone, tablet, or watch. Mobile applications often stand in contrast to desktop applications which are designed to run on d ...
s such as
Natural Cycles Natural Cycles is a mobile app designed to help women track their fertility. The app predicts the days on which a woman is fertility awareness, fertile and may be used for planning pregnancy and contraception. It was developed by scientist Elina Ber ...
.
Advantages
The Standard Days method (SDM) is increasingly being introduced as part of
family planning
Family planning is the consideration of the number of children a person wishes to have, including the choice to have no children, and the age at which they wish to have them. Things that may play a role on family planning decisions include marita ...
programs in developing countries. The method is satisfactory for many women and men. The low cost of the method may also enable it to play a useful role in countries that lack funding to provide other methods of
birth control
Birth control, also known as contraception, anticonception, and fertility control, is the use of methods or devices to prevent unwanted pregnancy. Birth control has been used since ancient times, but effective and safe methods of birth contr ...
.
Potential concerns
Failure rate
One concern related to the use of calendar-based methods is their relatively high failure rate, compared to other methods of birth control. Even when used perfectly, calendar-based methods, especially the rhythm method, result in a high pregnancy rate among couples intending to avoid pregnancy. Of commonly known methods of birth control, only the
cervical cap
The cervical cap is a form of barrier contraception. A cervical cap fits over the cervix and blocks sperm from entering the uterus through the external orifice of the uterus, called the ''os''.
Terminology
The term ''cervical cap'' has been ...
and
contraceptive sponge
The contraceptive sponge combines barrier and spermicidal methods to prevent conception. Sponges work in two ways. First, the sponge is inserted into the vagina, so it can cover the cervix and prevent any sperm from entering the uterus. Secondl ...
have comparably high failure rates. This lower level of reliability of calendar-based methods is because their formulas make several assumptions that are not always true.
[Kippley, p.154]
The postovulatory (
luteal
The corpus luteum (Latin for "yellow body"; plural corpora lutea) is a temporary endocrine structure in female ovaries involved in the production of relatively high levels of progesterone, and moderate levels of estradiol, and inhibin A. It is th ...
) phase has a normal length of 12 to 16 days, and the rhythm method formula assumes all women have luteal phase lengths within this range. However, many women have shorter luteal phases, and a few have longer luteal phases. For these women, the rhythm method formula incorrectly identifies a few fertile days as being in the infertile period.
Calendar-based methods use records of past menstrual cycles to predict the length of future cycles. However, the length of the pre-ovulatory phase can vary significantly, depending on the woman's typical cycle length, stress factors, medication, illness,
menopause
Menopause, also known as the climacteric, is the time in women's lives when menstrual periods stop permanently, and they are no longer able to bear children. Menopause usually occurs between the age of 47 and 54. Medical professionals often d ...
,
breastfeeding
Breastfeeding, or nursing, is the process by which human breast milk is fed to a child. Breast milk may be from the breast, or may be expressed by hand or pumped and fed to the infant. The World Health Organization (WHO) recommends that br ...
, and whether she is just coming off
hormonal contraception
Hormonal contraception refers to birth control methods that act on the endocrine system. Almost all methods are composed of steroid hormones, although in India one selective estrogen receptor modulator is marketed as a contraceptive. The origin ...
. If a woman with previously regular cycles has a delayed ovulation due to one of these factors, she will still be fertile when the method tells her she is in the post-ovulatory infertile phase. If she has an unusually early ovulation, calendar-based methods will indicate she is still in the pre-ovulatory infertile phase when she has actually become fertile.
Finally, calendar-based methods assume that all bleeding is true menstruation. However, mid-cycle or
anovulatory bleeding
An anovulatory cycle is a menstrual cycle characterised by the absence of ovulation and a luteal phase. It may also vary in duration from a regular menstrual cycle.
Patterns
While the normal human menstrual cycle typically lasts 4 weeks (28 days, ...
can be caused by a number of factors. Incorrectly identifying bleeding as menstruation will cause the method's calculations to be incorrect.
Embryonic health
It has been suggested that pregnancies resulting from method failures of periodic abstinence methods are at increased risk of miscarriage and birth defects due to aged gametes at the time of conception. Other research suggests that timing of conception has no effect on miscarriage rates, low birth weight, or preterm delivery.
Destruction of fertilized eggs
Luc Bovens has suggested that unprotected intercourse in the infertile periods of the menstrual cycle may still result in conceptions, but create zygotes incapable of implanting.
Bovens maintains that, if one defines abortion to include any destruction of fertilized eggs, then the use of the rhythm method probably results in a large number of abortions.
References
{{DEFAULTSORT:Calendar-Based Contraceptive Methods
Fertility awareness
Calendars