Relatively few Catholic couples in the United States use modern methods of natural family planning (NFP). So too, few Catholic physicians and health professionals prescribe the use of NFP methods for their patients. Reasons for low use of NFP methods include their perceived low efficacy; the complexity of learning, using, and teaching these methods; and the prolonged (and often unnecessary) required abstinence. Newer and simplified methods of NFP have been developed by physicians and scientists that are less complex and use modern technologies of detecting fertility and communicating instructions. Catholic physicians and scientists need to continue to answer the call by the Holy Fathers (from Pius XII to Benedict XVI) to develop secure and scientifically sound methods of NFP.
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DOI 10.1179/002436309803889377 10.1179/002436309803889377 Fehring et al. 2009, Fehring 2009
Cite this article
Fehring, R. J. (2009). Efficacy and Efficiency in Natural Family Planning Services. The Linacre Quarterly, 76(1), 9-24. https://doi.org/10.1179/002436309803889377
Fehring RJ. Efficacy and Efficiency in Natural Family Planning Services. Linacre Q. 2009;76(1):9-24. doi:10.1179/002436309803889377
Fehring, R. J. "Efficacy and Efficiency in Natural Family Planning Services." The Linacre Quarterly, vol. 76, no. 1, 2009, pp. 9-24.
A one-day meeting was held as a pre-conference to the Catholic Medical Association Annual Educational event in 2024. A panel of eighteen physicians, scientists, and researchers involved in NFP work was convened to review the available evidence in four topical areas: (i) evidence for effectiveness of NFP methods to postpone and achieve pregnancy, (ii) evidence for effectiveness in the postpartum and perimenopause transition periods, (iii) evaluate the current state of technology in NFP (specifically app and quantitative hormone monitoring), and (iv) evidence examining the impact of NFP on marital relations. In each topical area, the panel worked to reach a consensus opinion on the currently available evidence and identified priorities for further research. Results from these discussions and a set of priorities for further work are presented here.
An expert panel was convened to review the current evidence supporting use of NFP in various settings, utilization of new technology, and the impact of NFP on marital dynamics. Results from these discussions and a set of priorities for further work are presented here.
Fertility awareness-based methods (FABMs), also known as natural family planning (NFP), enable couples to identify the days of the menstrual cycle when intercourse may result in pregnancy ("fertile days"), and to avoid intercourse on fertile days if they wish to avoid pregnancy. Thus, these methods are fully dependent on user behavior for effectiveness to avoid pregnancy. For couples and clinicians considering the use of an FABM, one important metric to consider is the highest expected effectiveness (lowest possible pregnancy rate) during the correct use of the method to avoid pregnancy. To assess this, most studies of FABMs have reported a method-related pregnancy rate (a cumulative proportion), which is calculated based on all cycles (or months) in the study. In contrast, the correct use to avoid pregnancy rate (also a cumulative proportion) has the denominator of cycles with the correct use of the FABM to avoid pregnancy. The relationship between these measures has not been evaluated quantitatively. We conducted a series of simulations demonstrating that the method-related pregnancy rate is artificially decreased in direct proportion to the proportion of cycles with intermediate use (any use other than correct use to avoid or targeted use to conceive), which also increases the total pregnancy rate. Thus, as the total pregnancy rate rises (related to intermediate use), the method-related pregnancy rate falls artificially while the correct use pregnancy rate remains constant. For practical application, we propose the core elements needed to assess correct use cycles in FABM studies.
Fertility awareness-based methods (FABMs) can be used by couples to avoid pregnancy, by avoiding intercourse on fertile days. Users want to know what the highest effectiveness (lowest pregnancy rate) would be if they use an FABM correctly and consistently to avoid pregnancy. In this simulation study, we compare two different measures: (1) the method-related pregnancy rate; and (2) the correct use pregnancy rate. We show that the method-related pregnancy rate is biased too low if some users in the study are not using the method consistently to avoid pregnancy, while the correct use pregnancy rate obtains an accurate estimate. SHORT In FABM studies, the method-related pregnancy rate is biased too low, but the correct use pregnancy rate is unbiased.