Archive for the ‘NFP’ 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 and the Cervix Sign

Sunday, September 20th, 2020

Your Right to Know: The Cervix Sign

As indicated in the August 11 post of Dr. Edward F. Keefe’s COVERLINE article on the internal observations of cervical mucus, his patients taught him about changes in the cervix itself, changes that had not been previously reported in the medical literature. He first reported on this in 1962 in the Bulletin of the Sloane Hospital for Women. Fifteen years later he reported it in the International Review of Natural Family Planning, Vol.1, Number 1, Spring 1977. It is interesting both in its detail and in the responses he gives to questions about its effectiveness when used in systematic NFP.

As Dr. Keefe indicates in this article, squeamishness hinders some women from ever making the exam, and he addresses that issue. He never advocates a cervix-only system for purposes of avoiding pregnancy. In NFPI we teach the observation of the cervix as a supplement to the mucus and temperature signs. Experienced women have told us that the cervix sign is sometimes the best sign for them about their fertility or infertility, especially in extended breastfeeding amenorrhea or during premenopause.

If you would like to read his 1977 report, see

John F. Kippley

Natural Family Planning and the Temperature sign

Sunday, September 13th, 2020

Your Right to Know: The Temperature Sign

The temperature sign is an extremely valuable component of the science and art of natural family planning.

•An elevated temperature pattern provides a positive sign of being past ovulation.
•It provides a highly accurate way to determine both the beginning of the fertile time and the end of the fertile time.
•Twenty-one days of elevated temperatures provide a 99% degree of certainty that you have achieved pregnancy.
•It provides the single best predictor of the date of childbirth, and it takes only a few minutes to take one’s waking temperature.
•It can be used by itself, and it can also be used in a cross-checking way with the cervical mucus.

You have a God-given right to know all these God-given realities about the temperature sign.

Here’s a brief summary of how this information developed, and in what follows, Phase 1 = pre-ovulation infertility; Phase 2 = the fertile time; Phase 3 = post-ovulation infertility.

In 1877 Mary Putnam Jacobi found that a menstruating woman’s temperature rises about mid-cycle and remains elevated until the start of menstruation. She was a feminist of sorts, seeking to prove that menstruation was not a sickness that prevented women from working outside their homes.

A person of great interest to NFP history is Rev. Wilhelm Hillebrand, a German Catholic priest who had a scientific mind and simply wanted to help his parishioners. In the very early 1930s he was aware of the “rhythm” work of Dr. Kyusaku Ogino and Dr. Hermann Knaus and began advising couples according to the Knaus calendar-rhythm formula. Soon he had reports of three unplanned pregnancies. Then he remembered the temperature-based research of Dr. T. H. van de Velde reported in 1926.

In 1935 Fr. Hillebrand collected 76 temperature graphs from 21 women, and from this he invented the Calendar-Temperature method as it would be later called. In this system, a previous-cycle calculation such as “Shortest cycle minus 19” was used to determine the end of Phase 1, and Hillebrand’s genius was to insist that elevated temperatures were required to establish the beginning of post-ovulation infertility. He thus eliminated the weakest side of calendar rhythm. (The 19 Day Rule has since been changed to the 21 Day Rule and the 20 Day Rule.)

Over the years, various doctors contributed to our understanding of how to interpret temperature graphs for the start of Phase 3, and they also contributed to increasing the effectiveness of previous-cycle rules for the end of Phase 1. But there was nothing by way of published effectiveness data.

In 1967 Dr. G. K. Doering of Germany made a significant contribution to the science of natural family planning with his temperature-only study published shortly before Humanae Vitae. See the translation of his report at . Of great significance is that his “end-of-Phase 1” rule is based on the temperature pattern. This was unique because previous researchers had used an end-of-Phase-1 rule based on the length of the entire cycle such as “Shortest cycle minus 19.” Doering based his calculation on the first day of thermal shift in previous cycles, thus eliminating variations based on the length of the luteal phase (the days between ovulation and the start of the next menstruation).

In his study, Doering gives us statistics for two different groups— (1) those who engaged in the marriage act both in Phase 1 and in Phase 3, and (2) those who limited their marriage acts to Phase 3. In the first group, he found a 96.9 percent effectiveness rate that included all the marriage acts in what was clearly Phase 2. In the Phase 3-only group, the effectiveness rate was 99.2 percent. This was a temperature-only system with no cross-check from the disappearance of cervical mucus.

Dr. Konald Prem decided in the early 1970s that we could modify the Doering Phase 3 rule into a cross-checking sympto-thermal rule by requiring that that the three days of high-level temperatures must be cross-checked by a minimum of two days of mucus drying up to assure that the temperature rise is due to ovulation and not a cold or sickness. When this rule can be applied, it provides the earliest start of Phase 3 of any of the other STM or the mucus-only rules. In NFP International, we call this Rule K.

Konald Prem has also given us an accurate temperature-based rule for estimating the date of childbirth (EDC). The rule that doctors used almost universally previous to this time was the Naegele rule from the mid-19th century: start with the first day of the last menstrual period, add 1 year, subtract 3 months, and add 7 days—approximately 40 weeks. It works quite well when a woman ovulates about cycle day 14, but it is increasingly inaccurate when ovulation occurs a number of days after day 14, and it is worthless when a breastfeeding mother conceives before she has her first period.

The Prem rule uses the rise in post-ovulation temperatures. Take the first day of elevated post-ovulation temperatures, subtract 7 days and add 9 months. In a mid-Seventies article in a medical journal,he wrote that this is the most accurate way to predict the EDC, more accurate than much more elaborate and expensive procedures such as “estimation of uterine size by palpation or measurement, the dates of quickening and engagement of the fetal head and auscultation of the fetal heart tones with the head stethoscope…” or “biochemical and biophysical methods such as estriol, ultrasound and phospholipids…” (Konald A. Prem, “Assessment of Gestational Age,” Minnesota Medicine, September 1976, 623). For examples of how this knowledge has helped to avoid a premature induction of labor and to require an insurance company to cover the expenses of a premature baby, see page 70 of our manual, Natural Family Planning: The Complete Approach.

Breastfeeding mothers who conceived many months postpartum and before their first menstruation have expressed great gratitude for the Prem temperature-based rule.

Other benefits of recording temperatures are found when women experience breakthrough bleeding and irregular shedding. These are also described in our NFP manual. Among many married couples, a significant advantage of using the temperature sign is that it gets the husband involved, and this can be very helpful.

The weakness of the temperature sign is that when ovulation is significantly delayed, as happens during breastfeeding infertility and during premenopause, it does not signal the start of Phase 2. However, it does confirm continued non-pregnancy as long as the temperatures remain low. A second weakness, if it can be called that, is that it is so easy to take and record daily temperatures that some women ignore their mucus signs. I once heard Dr. John Billings cite this as a reason why he switched to a mucus-only system.

In NFP International we strongly recommend using both the mucus and the temperature in a cross-checking way.

We know that the elevated temperature reflects elevated levels of progesterone that is secreted by an ovarian follicle, the corpus luteum, after ovulation. I do not know why this hormone causes a woman’s waking temperature to rise, but it is a God-given reality.

And you have a God-given right to know these realities.

John F. Kippley