Select Page

For more information: visit the Natural Family Planning Research Database

“…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…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. 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…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 t
ir 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 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. A study of NFP and divorce is under way 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…

[Mary E. Kambic, Robert T. Kambic, MSH, Associate Scientist, The Johns Hopkins University , School of Public Health, Baltimore, Maryland, Ethics & Medics, May 2000, V. 25 No. 5; 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; [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; 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.]

Natural Family Planning Research Database

The Effectiveness of the Creighton Model Ovulation Method in Avoiding and Achieving Pregnancy
“Use Effectiveness of the Creighton Model Ovulation Method of Natural Family Planning”; Fehring, Richard J.; Lawrence, D.; and Philpot, D., Journal of Obstetric, Gynecologic, and Neonatal Nursing Vol. 23, No. 4 . May 1994. pp. 303-309
Click here