Archive for the ‘Mucus-only’ Category

Natural Family Planning and Relative Effectiveness

Sunday, October 18th, 2020

Your Right to Know: Relative Effectiveness

As mentioned previously in my comments about cervical mucus, the US Bishops established the Human Life Foundation in 1968 to support Humanae Vitae and to promote natural family planning. In the Seventies there was considerable debate about the relative effectiveness of the mucus-only “Ovulation Method” (OM) and the cross-checking “Sympto-Thermal Method” (STM) which uses mucus, temperature and previous cycle history. The Foundation persuaded the National Institutes of Health to run a scientifically sound study in 1976-1978 to compare the use-effectiveness of the OM and STM.

In the formal study, the investigators found an OM imperfect-use rate of 39.7 and an STM imperfect-use rate of 13.7 pregnancies per 100 years of use. In other words, the OM had an imperfect-use “avoiding” effectiveness rate of 60.3% and the STM had an imperfect-use “avoiding” rate of 86.3%. The OM group experienced six perfect-use pregnancies; the STM group experienced zero perfect-use pregnancies. In the words of the final report, “Results of this study show the STM to be superior to the OM of NFP in terms of use-effectiveness.” (Wade et al., “A randomized prospective study of the use-effectiveness of two methods of natural family planning,” Am. J. Obstet. Gynecol. 141:368, 1981, p.375)

Toward the end of the final report, the authors wrote: “It is of interest that after couples were informed in August, 1978, that a statistically significant trend in the pregnancy rate between the OM and STM groups had been found, almost all of the STM volunteers continued in training, and virtually all of the OM volunteers requested to be, and were, thoroughly trained in STM” (376).

In brief, when the relative effectiveness of the mucus-only “Ovulation Method” and the cross-checking “Sympto-Thermal Method” was hotly contested, the US Bishops sponsored a study which found that the STM approach was superior to the OM approach. You have a right to know these things.

Still, some or many dioceses seem to ignore that part of the science of NFP and continue to promote the mucus-only approach as if there is no difference.

Another comparison. In the effectiveness comparisons, not much attention has been paid publicly to the differences in the computation of effectiveness rates, and there is a big difference. The question is this: “How should we count pregnancies that result from not following the rules?”

The terminology has evolved over the years. In current terminology, “perfect-use” pregnancies refer to pregnancies of couples who became pregnant while following the rules. “Imperfect-use” pregnancies refer to pregnancies of couples who became pregnant while not following the rules. That seems rather straightforward, and most people in the NFP movement have accepted that standard.

Most is not all. Dr. Thomas Hilgers, author of the mucus-only “Creighton Model” and “FertilityCareTM” does not accept that standard. He argues that when a couple engages in the marriage act at a time defined as fertile or possibly fertile according to the rules, the spouses are engaging in “pregnancy-achieving behavior.” Well, certainly, but that is true for every method. The rest of the NFP movement counts such pregnancies as “imperfect-use” pregnancies, but Dr. Hilgers does not. The result is that there are relatively few “imperfect-use” pregnancies in his calculations, and that makes his system appear to be much more effective than it would be if he used the standard accepted by the rest of the NFP movement.

How can we tell? In 1985, Joanne Doud, a teacher of the Hilgers system, reported a study in which she claimed a very high imperfect-use rate of 96.2%. Fortunately, she also listed the number of pregnancies that the couples themselves regarded as unplanned. Using those numbers, the imperfect-use effectiveness was only 67% (Joanne Doud, “Use-effectiveness of the Creighton Model of NFP,” International Review of Natural Family Planning, Vol IX, No.1, Spring 1985). You have a right to know these things.

For purposes of comparing apples with apples and for credibility, the rest of the NFP movement accepts the statistical method used by the contraceptive birth control movement. Few in diocesan administration, however, seem to pay attention to the fact that the Hilgers system calculates its user-effectiveness rates in a way that is not accepted or practiced by anybody else in the NFP movement. Dioceses have paid thousands of dollars to have a single teacher trained in the Hilgers version of mucus-only without any comparative indication that his system is any better than the original Billings system or the cross-checking Sympto-Thermal Method.

What about seeking pregnancy? There have been no comparative studies about couples using different NFP systems to achieve pregnancy, and thus there is no evidence that any system of observing and recording the mucus sign is any better for achieving pregnancy than that used in any other system. Fertile mucus is fertile mucus, no matter how observed and recorded. Further, certain types of impaired fertility may be successfully resolved simply by improvements in nutrition and lifestyle.

On the other hand, when there is a case of difficult infertility, it is good to know that Hilgers-trained doctors may be able to treat certain defects with surgery or other medical techniques in what he calls NaProTechnology. It is also important to know that there are some couples in which one or both spouses are infertile and whose only morally sound hope for a child is the adoption of a baby who needs their loving care.

John F. Kippley

Natural Family Planning: Mucus-only Systems

Sunday, January 27th, 2019

Recently I saw a blog that raised my concerns about mucus-only systems.  First, some background.  The late Fr. Paul Marx OSB conducted an NFP symposium every summer in the Seventies.  I attended these from 1971 through 1978 and heard Dr. John Billings give his talk each year.  He was such a convincing speaker that he would leave me wondering why we taught the cross-checking Sympto-Thermal system.  That question evaporated when I realized that there was at that conference another meeting to which I was not invited.  The Ovulation Method (OM) teachers would get together to discuss real-life situations.  They were finding that in real life things were not as simple as in the talks by Dr. Billings.  The temperature sign can be a  tremendous help and especially when the mucus signs are ambiguous or difficult to interpret.  By the way, Fr. Paul Marx was a supporter of NFP International.

At the talks by Dr. Billings, I heard him say two things that are troubling to this day.  In one talk he explained why he and his associates had dropped the temperature sign.  He said it was too easy.  It was so easy to use and interpret the temperatures that their Sympto-Thermal Method (STM) users were getting sloppy with their mucus observations.  Thus, his method systematically deprives his mucus-only users of the very-easy-to-use temperature sign.  Our answer to this problem is to point out that each sign is very important, especially in some situations.  If a couple decides to use only one sign, that’s their business, but we strive to give them the freedom to choose.  I strongly object to the deliberate withholding of this information, the deliberate reduction of couples’ freedom to make informed choices.

I also heard Dr. Billings explain that his system does not teach the teachings of the Church regarding birth control.  He used the word “crutch” in saying that his method stands on its own merits as a method of birth control and does not need the “crutch” of religion.  The Hilgers system likewise advertises that it is open to people of all faiths.  He certainly doesn’t encourage any immoral behaviors, but his system does not explicitly teach Catholic teaching on unnatural forms of birth control.  A Hilgers user-couple once told us that such a lack of specific teaching led them to practice masturbation during the fertile time until they somehow got our materials.  In our manual’s witness chapter, one gentleman says he and his spouse used our 1996 manual for self-instruction but skipped the sections on morality and resorted to masturbation during the fertile time. They finally read those sections and repented.  I am sure that these cases are not at all exceptional.  In the mid-Seventies, a secular fertility-awareness book openly recommended oral sodomy although it condemned anal sodomy on grounds of being unsanitary.  I think it is imperative to state the specific unnatural forms of birth control.

Perhaps when the Billings dropped the teaching of morality, there were no immediate bad consequences because the users were made very much aware of the fullness of Catholic teaching by their Catholic education and parish priests.  Certainly that cannot be counted on today.

I am more convinced than ever that it is imperative to teach the covenant theology of the marriage act simply because it is so easy to grasp.  It also makes it very easy to understand the dishonesty of “marriage acts” outside of marriage.

Lastly, the Billings method of birth control is not as effective as it is sometimes claimed to be.  Right after Humanae Vitae, the U.S. bishops founded the Human Life Foundation to assist couples to live the teaching of the encyclical.  The Foundation persuaded the NIH to conduct an impartial study to determine the relative effectiveness of the STM and the OM.  It was published in 1981, stating that there were approximately twice as many surprise pregnancies in the OM group.  Drs. Billings and Hilgers criticized it at length even though they had been consultants to the study.  For example, they found fault with the study’s inclusion of unmarried couples.  Does anyone have good reason to think that unmarried couples are less motivated to avoid pregnancy than married couples? The bottom line is that the US Bishops through their Human Life Foundation sponsored a study which gave the above results, but many or most dioceses have ignored those results. In other words, while the OM may be very good, the comparative study showed that it is second best.

Couples have a right to know all the common signs of fertility, ecological breastfeeding, and the covenant theology of the marriage act.

For readers interested in what we teach at NFP International, go to and purchase Natural Family Planning: The Complete Approach.

John F. Kippley


Natural Family Planning: Adequate Instruction

Sunday, December 2nd, 2018

What constitutes adequate NFP instruction as part of Catholic education?  First, instruction in Natural Family Planning should be in the context of Christian discipleship and chastity. Catholic moral teaching must be integrated into the instruction. The NFP course should NOT be just a course in female and male fertility.

Second, the course should respect the first principle of educational psychology: you can choose only something that you know about. That means that couples should be taught not just one sign of fertility but all three of the common signs—basal body temperature, cervical mucus, and the cervix itself. Only in that way can students be free to choose among common and morally acceptable systems of fertility awareness. I don’t care what sign or signs they actually use, but fairness in fertility awareness requires this much.

Many priests and bishops have been led to believe that the mucus-only systems are just as good as or even better and more effective than the cross-checking mucus-and-temperature system. The US Bishops’ Human Life Foundation (1968-1993) persuaded the NIH to conduct an unbiased study to resolve the conflicting claims of the contrasting systems. Their report in 1981 stated that the cross-checking system was more effective because the Billings mucus-only system had more unplanned pregnancies by a ratio of two to one. Yet many dioceses still offer only mucus-only systems or give them so much backing that the cross-checking system can be found only with difficulty.

Third, NFP instruction should also include the teaching and promotion of Ecological Breastfeeding. That’s the form of baby care in which mother and baby remain together, and that mother-baby togetherness thus encourages and enables frequent nursing via the Seven Standards. Every kind of breastfeeding does some good, but the frequent suckling of Ecological Breastfeeding maximizes the great health benefits of breastfeeding for both baby and mother. It truly is God’s own plan for nutrition, protection, and spacing babies.

John F. Kippley