After Rhythm: The Development of NFP
Mary Shivanandan, S.T.D., John Paul II Institute
Ethics and Medics April 1995
Volume 20 Number 4
Enormous confusion exists among Catholics and non-Catholics alike about the various methods of natural family planning (NFP), and more importantly about its comparative effectiveness over against artificial forms of contraception. As the failure rates, abortifacient action, and health risks of hormonal contraceptives (e.g., bloodclotting, pulmonary embolism, and cerebral and coronary thromboses) have become more widely known, NFP has been increasingly recognized as a healthier and effective alternative. NFP has the further incomparable advantage of being in conformity with God's plan for our sexuality as reflected in Scripture and expressed in the Church's teaching on the inseparability of the unitive and procreative dimensions of sexuality. An historical survey of the development of NFP and a comparison of its effectiveness in both achieving and avoiding pregnancy may help to clarify its superiority vis-a-vis contraception.
Historically, advances in endocrinology made possible the development of both hormonal contraceptives, which suppress fertility, as well as the natural methods of family planning, which accept the natural rhythms of fertility. The first prerequisite for the development of both the Pill and NFP was a thorough understanding of the menstrual cycle and the effects of hormones on the cycle. Two signs of variations in the woman's menstrual cycle (aside from the menstrual flow) were observed by various researchers in the 19th and 20th centuries, the thermal or temperature sign and the cervical mucus sign, but there was still no understanding of how these changes related to the hormonal events of the menstrual cycle. It was only in the 1920s and early 1930s that the hormones, estrogen and progesterone, and their action on the reproductive system were discovered. The rise in estrogen is related to the ripening of an ovum or egg in the ovary while progesterone is secreted by the corpus luteum or yellow body left behind by the egg's rupture from the follicle.
The Rhythm Method (1929-32)
The Rhythm method was the first attempt to time intercourse according to the phase of the menstrual cycle. Kyusaku Ogino in Japan, from earlier research on corpora lutea, determined a formula for identifying fertility in women in 1932. It was based on the fact that after ovulation the duration of the period before the next menstruation is more or less constant with a normal range of 10-16 days. By counting backwards from menstruation, Ogino calculated the possible days of fertility and infertility. At about the same time, Herman Knaus in Austria also proposed a method of determining the fertile period based on his study of corpora lutea. Rhythm was not a satisfactory method of determining the fertile period because it depended too much on guesswork and not enough on scientific observation.
The Basal Body Temperature Method (1935)
A German Catholic priest, Wilhelm Hillebrand, began to recommend to his parishioners the Knaus calculations, but soon found a number of unplanned pregnancies occurring. Recalling the 1926 statement of T. H. Van de Velde that the corpus luteum causes a rise in temperature in the menstrual cycle, he began in 1935 to collect temperature records from 21 women. From the results he obtained, he developed the calculo-thermal approach (also called the basal body temperature method or BBT), which combined a calendar calculation for the beginning of the cycle and the temperature rise for the postovulatory phase. For the first time a woman had available an accurate scientific observation for identifying the postovulatory phase of the cycle which, if intercourse was confined to the postovulatory period, provided a method almost as effective as the contraceptive pill developed more than two decades later (see Christopher Tietze, "Ranking of Contraceptive Methods by Levels of Effectiveness," Advances in Planned Parenthood, 6 [April 9-10, 1970]). But such a method required too much abstinence if intercourse was postponed until the postovulatory phase and did not provide accurate information on the preovulatory phase where most of the variation occurs.
The Billings Method: Monitoring Mucus (1950s)
Two decades later, Dr. John Billings, a neurologist, was asked to assist married couples coming for instruction in fertility regulation at a Catholic marriage guidance center in Melbourne, Australia. He found both Rhythm and BBT inadequate for irregular cycles, which occur in all women sometimes, especially during breastfeeding and premenopause, and in some women most of the time. Especially during lactation, ovulation may occur without a previous menstruation, so that menstruation is not a good marker for predicting the onset of the fertile period. In searching the literature he found that a certain kind of mucus secreted by the cervix accompanies ovulation and he set about to study it.
Working with the women who sought advice from the center, he discovered that they could readily identify changes in the quality of mucus as ovulation approached. Professor J. A. B. Brown assisted the research on the mucus pattern by monitoring the menstrual cycles of the women through daily measurement of estradiol and pregnanediol. It was found that the women's observations of the mucus as it changes from cloudy and tacky to clear, slippery, and stringy, coincided with the levels of estradiol and pregnanediol found in the urine. Further hormonal studies with the help of Dr. H. G. Burger monitored the occurrence of the pituitary gonadotropins, FSH and LH, in the menstrual cycle. It was clearly shown that ovulation occurs between the LH surge and the secretion of progesterone. Here, then, was a method of identifying the fertile period based on sound scientific principles and observation, which did not depend on the length or regularity of the menstrual cycle. Dr. John Billings and his wife, Dr. Evelyn Billings, were not the first to incorporate the mucus sign into a method of natural family planning, but they were the first to rely on the mucus sign exclusively and to develop rules for its use as a complete method in itself.
The Sympto-Thermal Method (1950-70) While the Billings abandoned the temperature and additional signs of fertility such as the opening and closing of the cervix (a sign discovered by Dr. Edward F. Keefe in the early 1950s), other physicians and couples incorporated all the signs into the symptothermal method of natural family planning. Foremost among these were John and Sheila Kippley, who founded the Couple to Couple League, SERENA of Canada, and Dr. Joseph Roetzer of Austria. By the mid-1970s two highly effective methods of natural family planning had been developed, which could be successfully applied by couples either to avoid or achieve pregnancy throughout their reproductive life span.
Many other medical researchers have since contributed to the refinement of natural family planning, most notably Eric Odeblad of Sweden who has identified four different types of mucus and their effect on sperm migration and Thomas Hilgers of the Pope Paul VI Institute, Omaha NE, who has documented extensively the effect of inadequate fertile mucus on the occurrence of infertility. These developments are especially remarkable in view of the scarcity of funds for natural family planning research compared to funds and expertise available for contraceptive research from major foundations, medical institutions, government and private industry.
Effectiveness of NFP vs. Other Methods
While for many years natural family planning was classified with "traditional" or "folk" methods of family planning and considered equally unreliable, the family planning field has come to recognize the high method-effectiveness of modern NFP. Contraceptive Technology, ed. Robert A. Hatcher et al. (NY: Irvington, 1994) cites 2 and 3 percent as the "accidental" pregnancy rate within the first year of use if the sympto-thermal and ovulation methods are used perfectly (p. 652). Dr. Hanna Klaus cites an even lower rate of 0-2 percent pregnancies ("Action, Effectiveness and Medical Side-effects of Common Methods of Family Planning," Current Medical Research [Washington, DC: DDP for NFP, 1993]). Since couples are often ambivalent about another pregnancy, the range of use-effectiveness varies from a high of 99 percent to 80 percent. (Use-effectiveness rates refer to the success with which couples use the method in everyday life.) Competent instruction also affects pregnancy rates. Some of the highest use-effective rates have been recorded in developing countries such as India and Indonesia.
Contraceptive Technology rates modern NFP higher in method-effectiveness than all barrier methods, giving only hormonal methods and the IUD a higher rating. The Alan Guttmacher Institute also rates its use-effectiveness as comparable to the condom and more effective than other barrier methods (Preventing Pregnancy, Protecting Health: A New Look at Birth Control Choices in the United States [NY: Alan Guttmacher Institute, 1991]). In addition it has one of the highest continuation rates of any family planning method. Couples particularly appreciate its unique capacity among family planning methods to achieve as well as avoid pregnancy, the equal responsibility it calls for from husband and wife, and the opportunities it provides to enhance marital communication.
In spite of NFP's high effectiveness rates, couples are still routinely steered to "a more reliable method" of contraception (See, e.g., Contraceptive Technology, 330). It may be surmised that effectiveness is not so much the issue as the abstinence, or, in Christian terms, marital chastity, required to practice natural family planning (8-12 days in an average cycle).
The Science of Natural Family Planning
Mary E. Kambic, Robert T. Kambic, MSH
Ethics and Medics May 2000
Volume 25 Number 5
Despite the Church’s official support for the use of natural family planning (NFP), Catholic couples use the pill, condom, diaphragm, and get sterilized at the same rate as non-Catholics [F. Althaus, “U.S. Religious Groups Vary in Patterns of Method Use, But Not in Overall Contraceptive Prevalence,” Family Planning Perspectives, 23.6 (Nov.–Dec. 1991): 288–90]. The reasons for this are complex, but include the fact that the message is neither preached by clergy nor accepted by laity. On the other hand, there is both interest in and misinformation about NFP today. We find people around the world dedicated to its promotion and development. The purpose of this article is to review the scientific findings which are the foundation of NFP with the expectation that both preachers and teachers of NFP will use this information to renew acquaintance with and commitment to NFP.
We begin by reviewing the methods themselves and how well couples use them to time the births of their children. The effectiveness of NFP methods, when properly used, is equal or greater than that of barrier methods. We touch upon the shibboleth that the use of these methods may lead to birth defects or spontaneous abortions. The question of abstinence and reduced intimacy is examined and acknowledged. Finally, we examine the role of NFP in the diagnosis and treatment of infertility.
Various Methods of NFP
Most adult women in the world know that they can become pregnant for only a few days each month, generally about midcycle for women who are regular in their cycle. NFP is a body of knowledge based on naturally occurring signs and symptoms, that teaches women how to identify these days. The modern methods can identify the fertile time even in women who are irregular and amenorrheic.
The Calendar Rhythm method is the original NFP method developed simultaneously in Japan and Germany in the 1930s. It is the method commonly associated with NFP but has an undeservedly bad reputation because couples neglect to use it properly. It is simple and does not require daily observations as do the modern methods, but the lack of daily observations means chance is involved in its use.
The Basal Body Temperature (BBT) method became popular in the 1940s. The monthly temperature rise around midcycle gives a clear sign that the time of fertility is past but tells the woman nothing about the fertility of days prior to the rise. Then in the 1960s in Australia, Drs. John and Evelyn Billings realized that women who are aware of their daily cervical mucus secretions can know for each day of the menstrual cycle whether or not they are able to become pregnant on that particular day. This stunning discovery meant that irregular and breast-feeding women could use mucus observations to avoid conception and freed NFP users from the need for cycle regularity. Mucus awareness will be used by generations of women in the future to monitor reproductive health and plan families.
The three major methods, calendar, BBT, and mucus, are taught alone or in combination and have been christened many names—Sympto-thermal (ST), Ovulation Method (OM), Creighton Method, Billings Method, etc. Biologically, the methods are the same whatever the alias, and a woman’s charting of her symptoms is universally understood. In addition to the three major NFP methods there are other minor fertility signs such as intermenstrual pain and breast tenderness.
Effectiveness of the Methods
As health educators, we want to know about couples’ birth spacing intention and behavior. First, do couples want children now, want children later, or do they want no (more) children? Secondly, if they are using a birth control method, are they using it correctly? These two factors largely determine whether or not a woman will become pregnant while using any method. Couples who are determined to avoid pregnancy will have far fewer pregnancies than those who want more or are undecided about more children. And couples who bend or break the rules of the method of birth spacing they are using will become pregnant much more often, especially those who do not follow the rules of NFP.
The results of the many USA and international NFP studies lead to an incontrovertible conclusion. NFP use is as effective as barrier methods of family planning, which include the condom, foam, and diaphragm. Between 10 and 15 of 100 couples will become pregnant over the course of a year using NFP. Most of these pregnancies will occur because the couple did not follow the rules for NFP use. On the other hand, when used according to the rules, NFP is very effective. Most interestingly, when the rules are scrupulously followed, only 1 to 3 couples of 100 over the course of a year will become pregnant. The couple has control of their use of the method and their behavior determines their chances of becoming pregnant. Thus NFP can be used with assurance to avoid conception [R.T. Kambic, “The Effectiveness of Natural Family Planning Methods for Birth Spacing: A Comprehensive Review,” in Human Fertility Regulation: Demographic and Statistical Aspects, Sandro Girotto and Franco Bressan eds. (Verona: Edizioni Libreria Cortina: 1999), 63–90.
Even today one can still read in obstetrical and gynecological textbooks that NFP use may cause birth defects. These allegations are the result of hastily written attacks on Humanae vitae after its publication in 1968. Papers in scientific journals stated that periodic abstinence (natural family planning) users could have more spontaneous abortions or birth defects directly related to the use of these methods. These reports are few in number and methodologically unsound, but their shadow lingers on.
Johns Hopkins and colleagues from research institutions around the world conducted the first scientific study of NFP pregnancies in 1994. This study of 868 women and their babies found no relationship between spontaneous abortion and NFP or birth defects and NFP. Indeed, NFP users seemed to be a bit healthier than average [R.H. Gray, J.L. Simpson, R.T. Kambic, J.T. Queenan, P. Mena, A. Perez, M. Barbato, “Timing of Conception and the Risk of Spontaneous Abortion among Pregnancies Occurring During the Use of Natural Family Planning,” American Journal of Obstetrics and Gynecology 172 (1995): 1567–1572.]
Abstinence and Intimacy
NFP is used with abstinence from sexual intercourse during the fertile time if the couple wants to avoid pregnancy. It is possible to monitor fertility and to use barrier methods during the fertile time to avoid conception. However, NFP should be used with abstinence. There are several reasons for this. First is the Catholic Church’s proscription against any form of artificial method use. Second, the only time that women can get pregnant is the fertile time, which is the time during which barrier methods actually work to prevent pregnancy. If a woman does not want to become pregnant, but has sexual intercourse during a fertile time, there remains the possibility of pregnancy through contraceptive failure.
Detractors point out that NFP users have less opportunity for physical intimacy. On average, people in the USA have sexual relations about seven to eight times per month. There are a few studies of the frequency of sexual relations among NFP users. Our study at Johns Hopkins shows that for NFP users intending to avoid conception, sexual relations occurred between five and six times per month and for those not trying to avoid conception, seven to eight times per month. It is true that NFP users not wanting a child have less frequent sexual relations than the average American.
There are benefits to using NFP that place abstinence in context. First, there are no medical contraindications and no side effects to NFP use. Neither the husband nor the wife has the burden to bear alone. NFP use provides a deep and rich understanding of sexuality and reproduction in the context of the marriage relationship. Through awareness of and education about the respective reproductive functions of the male and female body, NFP provides an additional dimension of communication and respect within the marriage bond.
NFP users themselves learn to deal with abstinence in the context of their relationship. Each couple is different and if the couple is committed to NFP, they work on this issue as they do with other areas of their relationship. Some couples find that the time of abstinence is a time of anticipation, much like an engagement. Others have intercourse more frequently during the infertile time and still others focus their energy in other directions.
NFP, Divorce and Infertility
A commonly held perception is that NFP users do not get divorced. Somehow the use of NFP acts as a glue and keeps the marriage together and on track. NFP teachers are liable to promote NFP as a way to keep marriages healthy. We polled NFP leaders about their experience. They reported that the percentage of users getting divorced was minuscule compared to the general population rate of about 50%. The impression that NFP users do not separate is supported by the experience of NFP program directors. The National Catholic Register Foundation has funded a study of NFP and divorce in order to look into this matter in detail.
If these verbal reports are borne out by the study, NFP users probably do rarely divorce. But NFP use is most likely a sign of underlying harmony, strength of relationship, and commitment, rather than a cause. NFP use can strengthen these aspects of a relationship but cannot create them where they do not exist. Most NFP programs ask the husband and wife to come to instruction as a couple. The man participates by learning about his wife’s reproductive system, her signs, symptoms, and helps with charting and support.
Increasingly today, there are many couples who come to NFP to plan a pregnancy. A woman is fertile for many years until menopause and the average couple will have only two children during these years. Young couples may decide to delay having their first pregnancy until years after they are married and then when they try to become pregnant find that pregnancy is not forthcoming. When a couple is not able to become pregnant after one year of attempting to conceive, they are ready for infertility consultation, a large lucrative business.
One avenue open to these couples is to chart their most fertile times and discover any irregularities in the woman’s signs and symptoms. (Women are infertile in about 50% of the couples coming for counseling and the other 50% is either male infertility or unknown .) Knowing about their fertility increases confidence and helps to reduce the anxiety of infertility by giving couples some indication of their fertility status. Additionally, NFP charting is helpful to the infertility specialist working with the couple to achieve a pregnancy.
Those wanting to use NFP should work with an experienced teacher. There are NFP programs and teachers throughout the USA and around the world. NFP is healthy, safe, and effective. Catholics should review the reasons behind the Church’s commitment to it and reflect that it has something to teach us all about our continuing struggle with life here on earth.
Mary E. Kambic
Robert T. Kambic, MSH
Associate Scientist
The Johns Hopkins University
School of Public Health
Baltimore, Maryland
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