Natural Family Planning

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Natural family planning (NFP) is a generalized term that refers to methods of self-monitoring natural biological signs and symptoms of fertility. The purpose of NFP is to identify the days of fertility and infertility during a woman's menstrual cycle. Knowing this information enables a couple to either avoid or achieve a pregnancy. Inherent in the use of NFP is that couples abstain from intercourse during the times of fertility if they wish to avoid pregnancy. Natural family planning has also been referred to as "periodic abstinence," "rhythm," and "fertility awareness."

History. Although many previous scientific studies contributed to the development of natural methods of family planing, it was not until the late 1920s that two physician scientists discovered a key ingredient that led to the formulation of the first reliable method of natural birth regulation. Experiments by Dr. Kyusako Ogino from Japan and Dr. Herman Knaus from Germany provided them with information to estimate the approximate time of ovulation in a woman's menstrual cycle and to determine that once a woman ovulates there will be approximately 14 days until her next menses. From this information (and knowing the approximate life span of the woman's egg and man's sperm), they independently developed formulas for estimating the fertile times in a woman's menstrual cycle. These formulas are called the "calendar method" and later simply "rhythm" as adapted from the title of a popular book written on the method by Leo Latz, M.D. (1946) an American physician.

Reproductive scientists have known since the early part of the twentieth century that a woman's body temperature rises about 2 to 4 degrees after ovulation. However, it was not until the mid-1930s that a Catholic parish priest (Fr. Wilhelm Hillebrand from Germany) first applied this knowledge to the use of natural birth regulation. A number of his parishioners became pregnant after using the rhythm method to avoid pregnancy. Concerned about these pregnancies, Fr. Hillebrand instructed women to take their daily waking temperatures along with the calendar formulas to determine their fertile period. This method of natural birth control was later called the basal body temperature method or "BBT."

As early as the ninth century a number of physicians and scientists speculated that the fertile time of a woman's menstrual cycle occurred around the time a watery cervical-vaginal fluid was secreted. However, it was not until the 1930s and 1940s that scientists were able to correlate this stretchy, watery, slippery mucus with ovulation. A few physicians subsequently applied this knowledge as a means of monitoring fertility along with calendar formulas, changes in body temperature, and cervical changes. These methods collectively have been called the Sympto-Thermal methods, "STM" for short (or in Europe the double check or multiple index method).

In the 1960s, a husband-wife physician team from Australia, Drs. John and Evelyn Billings, discovered that monitoring the sensations and changes in cervical-vaginal fluids throughout the menstrual cycle was a simple and accurate means of determining the fertile and infertile times of the cycle. A large five-country study of the Billings Method or what is now called the Ovulation Method (OM) was conducted in the late 1970s by the World Health Organization. The WHO study confirmed the simplicity, accuracy, and effectiveness of the OM.

During the 1970s a number of variations and standardized forms of the sympto-thermal and cervical mucus (only) methods were developed. Most notable in the United States were the Creighton Model (cervical mucus only) system developed by Thomas Hilgers, M.D. (Hilgers 1995) and colleagues; the Family of the Americas cervical mucus only system developed by Mercedes Wilson (Wilson 1998); and the teaching system of the sympto-thermal method developed by John Kippley (Kippley 1996) (in conjunction with Konald Prem, M.D. at the University of Minnesota).

Since Ogino and Knaus developed the calendar formulas, technological devices have also been available to aid women and couples in monitoring their fertility. Such simple devices as beads, fertility wheels, and thermometers continue to be used as simple tracking systems. Recent scientific discoveries now allow women to track their fertility through computers, Internet programs, and with electronic hormonal fertility monitors. Newer methods of NFP that incorporate this modern technology are now being developed and tested.

Scientific Foundations. Recent reproductive research has confirmed that women have a six-day window of fertility during their menstrual cycle, namely, the day of ovulation and the five previous days. Determining the beginning and end of these six days and the peak of fertility is the goal of modern NFP. A woman's fertility begins when an egg (or ovum) in her ovaries starts to ripen in a small vessel called a follicle. The follicle produces a female hormone called estrogen that stimulates cells along the opening of her cervix to produce mucus. The mucus at first appears sticky, tacky, and cloudy but progresses to a very watery, stretchy, and slippery consistency at peak. Once a woman ovulates and the ovum is released from the follicle, the cells of the follicle change and produce another hormone called progesterone. Progesterone heats up the woman's body and causes the mucus to dry up at the cervix. After ovulation, the egg only lives from 12 to 24 hours. Therefore, once a woman reaches her peak fertility and ovulates, she is at the beginning of the end of her fertile window. The reason that a woman's fertility is about six days is because the sperm from a man can live in good cervical mucus for three to five days. If a couple has intercourse when the egg is ripening and the follicle is stimulating good cervical mucus, then the sperm can survive to fertilize the egg three to five days later.

There are a number of natural biological markers used in modern methods of NFP to help couples determine the beginning and end of their fertile period. The most common biological indicators are (1) changes in the characteristics of cervical mucus, (2) changes in the cervix, (3) changes in the daily waking body temperature, and (4) changes in female reproductive hormones. Some modern methods of NFP also continue to use "rhythm" formulas to determine the beginning and end of fertility.

One or more of the following fertility markers indicates the beginning of the fertile time in a woman's menstrual cycle: a change of sensation at the vulva from dry to sticky, tacky or moist; the presence of cervical mucus; the cervix starts to soften and rise; rising levels of estrogen as detected in the urine; and the length of the shortest of the last 6 cycles minus 20 days.

The peak of fertility (i.e., the estimated time of ovulation) is indicated by one or more of the following biological indicators: the last day of clear, watery, stretchy, slippery mucus and/or lubricative sensation; a rise in the resting body temperature of 2 to 4 degrees; the cervix is soft, open, and high in the vagina; peak levels of luteinizing hormone (LH) detected in the urine; rising levels of progesterone detected in the urine.

The end of fertility is determined by counting three (and sometimes four) days after the above biological markers are recorded. The end of fertility can also be determined by the length of the longest of the last 6 to 12 cycles minus 10 days. A more accurate and scientific determination comes from detecting urinary metabolites of the rising levels of the hormone progesterone, confirming that ovulation has taken place. There are many other biological indicators such as salivary or vaginal electrical resistance, salivary ferning, glucose levels, vaginal-cervical mucus volume, and others that have been and continue to be tested as possible self-monitored signs of fertility.

Most of the above self-detected biological indicators of fertility have been tested to validate their accuracy in detecting ovulation and the peak of fertility. The current gold standard of validating the day of ovulation is through the use of serial ultrasound to detect the growing and collapsed follicle. Based on the correlation with this gold standard, the most accurate self-indicators of ovulation are measures of urinary metabolites of LH, estrogen, and progesterone through the use of electronic fertility monitors and urinary (chemical assay) type test strips. Research also indicates that the peak day in cervical mucus (i.e., the last day of clear, stretchy, slippery mucus and/or lubricative sensation) varies around the day of ovulation plus or minus three days 99% of the time. Hence the instruction to count three days after the peak day as the end of fertility.

There have been numerous studies to determine the effectiveness of the various systems of NFP to avoid pregnancy. When systems of NFP are taught and used correctly, they range in effectiveness to avoid pregnancy (based on 100 women over 12 months of use) from 85% with calendar formulas to close to 99% with double indicator methods. The effectiveness in typical use drops to a range of about 75 to 90% largely due to the lack of compliance in following basic instructions. There have been few comparative studies on the effectiveness of the various systems of NFP.

Church teaching. The morality of this method of avoiding conception must be judged within the total context of the modern couple's marriage vocation, in relation to which the practice of NFP constitutes a means to an end.

Morally indifferent means. Considered in itself, the practice of NFP does not constitute a deviation from right moral order in the use of sex. pius xi, in the encyclical casti connubii, stated that having intercourse during the infertile times to avoid pregnancy is not an act against nature. This teaching was echoed by paul vi in the encyclical humanae vitae. Marriage does not oblige couples to engage in conjugal relations at any specific time. Neither avoidance of intercourse during the fertile period of a cycle nor restriction of its use to sterile periods violates the integrity of the marital act. Profiting from their knowledge of the normal functioning of the female reproductive system, couples may restrict intercourse to those periods that are considered most favorable for either the avoidance or the promotion of pregnancy. In contrast to contraception, which constitutes a deliberate attempt directly to inhibit or impede the normal progress of the physiological process of reproduction voluntarily initiated by the couple when they engage in marital relations, the practice of NFP fully respects the intrinsic natural structure of the conjugal act and in this regard must be considered a morally indifferent means for regulating family size.

Requisite conditions. Because the practice of NFP involves the deliberate restriction of marital relations to limited periods during the menstrual cycle, the conditions required for its morally licit use are determined by the demands of marriage. First, both partners must freely agree to the practice. Second, both partners must be capable of bearing the possible tension and strain that may result from the use of this practice. If the restriction of marital relations to limited periods seriously threatens the growth of mutual love and harmony between husband and wife, the couple must seek adequate means to modify the situation or cease the practice. Third, couples must have sufficient reason for employing this practice. As pius xii pointed out in an address to the Italian Catholic Union of Midwives on October 29, 1951 (Vegliare con sollecitudine ), marriage is a state of life that confers certain rights and also imposes the fulfillment of a positive work, namely, to provide for the conservation of the human race. This obligation is serious, though in the case of a given couple special circumstances or conditions of a medical, eugenical, economic, or social nature may render its fulfillment inopportune or unreasonable either for a time or throughout marriage. Hence, although it would be seriously sinful for a childless couple to employ NFP throughout marriage without a serious excusing reason, couples who generously accept their obligation to have children may licitly make use of this practice both for spacing pregnancies and for regulating family size in accord with a reasonable estimate of their parental capacities.

Common objections. The practice of NFP has been subjected to criticism on various grounds. In addition to those who reject the Church's traditional teaching regarding the morally licit means of regulating family size, some object to the practice because they judge that its use implies lack of trust in providence and will lead to a "contraceptive mentality." Yet authentic trust in Providence does not free couples from personal responsibility, but requires that they exercise prudent judgment in fulfilling their procreative mission. Granting that the temptation to selfishness is perennial, couples who are serious enough about their vocation to follow the Church's teaching regarding contraception are not likely to reject the privilege of parenthood.

A further set of objections stems from the belief that NFP creates undue anxiety and seriously inhibits the spontaneous expression of marital love. Like all other methods of family regulation short of absolute continence, the practice of NFP does involve some uncertainty and requires consistent foresight and care, though wellmotivated couples apparently find this no insurmountable obstacle. The required restriction of intercourse to limited periods obviously inhibits spontaneity in expressing this form of marital love, yet one must carefully distinguish between spontaneity of sexual expression and spontaneity in expressing love. The former is necessarily curbed by the demands of justice and charity as well as by the normal exigencies of social life; NFP inhibits the latter only if the couple has developed no alternate means of expressing love. Acquiring the disciplined control required by NFP does involve personal sacrifice, but marital relations can retain their significance as authentic expressions of love only if they foster the couple's integral development as Christian partners and parents.

Relationship to the vocation of marriage. Like all authentic vocations, marriage is designed to provide for the Christian's full development and sanctification in the service of Christ. It differs specifically from other vocations in its special mission, which is to provide for the couple's mutual, complementary fulfillment in a procreative union. Although all marriage partners accept an enduring commitment to foster their mutual happiness and perfection in Christ by dedicating themselves to the service of life, individual couples may differ widely in regard to both their parental abilities and the conditions or circumstances under which they must live. Because there exists no necessary relationship between procreative capacity and the ability to raise a family, many couples find it difficult to reconcile their normal expressions of marital love with the demands of the moral law. It is precisely in this context that the practice of NFP assumes primary significance. Provided they generously dedicate themselves to having a family, couples now have available a morally licit, reliable means of spacing pregnancies and regulating family size. The method requires sacrifice and self-mastery, yet these traits characterize all authentic expressions of love and are not beyond the strength of couples who have recourse to prayer and the Sacraments.

Prompted by the writings of Pope john paul ii, the Church in recent years has frequently articulated its understanding of human sexuality in terms of a "theology of the body." The conjugal act is an act of total reciprocal self-giving of husband and wife. When a couple uses contraception, they no longer are totally giving of themselves but rather are conditional in their love-making. The contraceptive act is in a sense a living "lie" or falsification of the inner truth of the conjugal act. In the 1982 apostolic exhortation, Familiaris consortio, Pope John Paul II reiterated that the differences between artificial contraception and methods of natural birth regulation were irreconcilable. The teachings in Familiaris consortio are reflected in the Catholic Catechism of the Catholic Church, which says "periodic continence, that is, the methods of birth regulation based on self-observation and the use of infertile periods, is in conformity with the objective criteria of morality. These methods respect the bodies of the spouses, encourage tenderness between them, and favor the education of an authentic freedom" (2370). In the 1995 encyclical evangelium vitae, John Paul II encouraged all married couples to learn NFP and called for the promotion of centers of NFP as a means to build a culture of life.

Bibliography: e. l. billings, j. j. billings, and m. caterinich, Billings Atlas of the Ovulation Method (Melbourne, Australia 1989). European Society of Human Reproduction and Embryology (ESHRE), "Optimal Use of Infertility Diagnostic Tests and Treatments," Human Reproduction 15 (2000): 723732. r. j. fehring, "New Technology in Natural Family Planning," Journal of Obstetric, Gynecologic, and Neonatal Nursing 20 (1991): 199205; "Review and Analysis of the Peak Day," Current Medical Research: A Supplement of NFP Forum 10 (1999): 916. r. j. fehring and a. schlidt, "Trends in Contraceptive Use among Catholics in the United States," Linacre Quarterly (2001). t. w. hilgers, The Scientific Foundations of the Ovulation Method (Omaha 1995). r. kambic, "The Effectiveness of Natural Family Planning," Current Medical Research. A Supplement of NFP Forum 11 (2000): 1116. j. kippley, The Art of Natural Family Planning (Cincinnati 1996). h. knaus, Periodic Fertility and Sterility in Women. A Natural Method of Birth Control (Vienna 1934). l. latz, The Rhythm of Sterility and Fertility in Women (Chicago 1946). k. ogino, Conception Period of Women (Harrisburg, Penn.1934). a. j. wilcox, c. r.weinberg, and d. d. baird, "Timing of Sexual Intercourse in Relation to Ovulation: Effects of the Probability of Conception, Survival of the Pregnancy, and Sex of the Baby," New England Journal of Medicine 333 (1995): 15171521. m. wilson, Love and Fertility (Dunkirk, Md. 1998). World Health Organization (WHO), "A Prospective Multicentre Trial of the Ovulation Methods of Natural Family Planning. II. The Effectiveness Phase," Fertility and Sterilization 36 (1981): 591598. r. f. vollman, "Wilhelm Hillebrand, The First Teacher of the STM," in a. zimmerman, ed., Natural Family Planning, Nature's Way God's Way (Milwaukee 1980).

[r. j. fehring/

j. l. thomas]