A Belgian pilot-study conducted in the framework of the prospective European multi-center study (University of Düsseldorf) tried to establish the use-effectiveness (a sine qua non condition for its acceptance in Europe) of natural family planning.
Material and Methods
84 participants provided data (sympto-thermal chart and related information) on 1,750 cycles where family planning intention was to avoid a pregnancy. The average age of the women was 32 years. A contraceptive method (mainly oral contraceptives) was employed previously by 61% of them. The sympto-thermal method used by the test group highlights the beginning and the end of the menstrual cycle's fertile period by a double check. As to the start of the fertile period, the criteria are: a calculation on the length of the previous twelve cycles and the first sign of mucus at either the vulva or the cervix. Indicators of the end of this phase are: the third day of high temperature and the fourth evening after either the peak mucus day or the peak cervix day. 75% of the women involved generally use the cervical auto-palpation.
Results
No method failure at all has been detected. Two unplanned pregnancies occurred due to user failure. The total Pearl index for the study was 1.4. When examining only those cycles (85% of the reported cycles) where no protected sexual intercourse occurred during the fertile phase, practical efficacy of the method analysed was 1.8 according to Pearl index. Furthermore, taking into account protected and unprotected sexual intercourse occurred during the fertile phase, we observed that sexual abstinence was practised during the "risk" period of 75% of the cycles.
Conclusions
The results of this test study demonstrate the practical efficiency of a modern natural family planning method. The high level of cycles during which periodic abstinence was employed testify to the acceptability of the method used.
sympto-thermal method natural family planning effectiveness prospective study, natural family planning Pearl index user failure method failure, cervical mucus temperature double check fertility awareness, European multicenter study natural family planning efficacy, periodic abstinence fertile phase acceptability NFP, de Leizaola Belgian pilot study symptomatic thermal method, cervical auto-palpation sympto-thermal method fertility awareness, natural family planning avoiding pregnancy use effectiveness, fertile window identification mucus observation basal temperature, modern NFP method prospective efficacy acceptability study
de Leizaola et al. 1998, de Leizaola 1998
Cite this article
de Leizaola, M. A. (1998). Prospective study of the efficacity of a recent symptomatic-thermal method of natural family planning. Journal de gynecologie, obstetrique et biologie de la reproduction, 27(2), 174-180.
de Leizaola MA. Prospective study of the efficacity of a recent symptomatic-thermal method of natural family planning. J Gynecol Obstet Biol Reprod (Paris). 1998;27(2):174-180.
de Leizaola, M. A. "Prospective study of the efficacity of a recent symptomatic-thermal method of natural family planning." Journal de gynecologie, obstetrique et biologie de la reproduction, vol. 27, no. 2, 1998, pp. 174-180.
Knowledge of the fertile and infertile phases of the menstrual cycle can be applied to conceive or to avoid pregnancy. Fertility intentions and sexual behaviors during the fertile time may influence whether and when pregnancy occurs. The Creighton Model FertilityCare System (CrMS) is a specific system of fertility appreciation used to conceive or to avoid pregnancy. The objective of this paper is to report intentions, behaviors, and pregnancy rates during use of the CrMS among couples who initially intended to avoid pregnancy.Data and methodsWe analyzed a prospective cohort study conducted in 17 CrMS centers across the USA and Canada, following 296 couples for up to one year after onset of initial use of the CrMS to avoid pregnancy. Baseline data included demographics, motivations, and pregnancy intentions for each partner. Couples contributed 2894 menstrual cycles, most of which had data collected (by questionnaires and daily diary) on cycle-specific pregnancy intentions, days of potential fertility, and fertility behaviors. Pregnancies were prospectively actively ascertained. We found a high concordance (91%) in cycle pregnancy intentions between partners. However, 44% of cycles with strong intentions to avoid pregnancy included intercourse on potentially fertile days or days of undetermined fertility status. Across all sensitivity scenarios, cumulative 13-cycle pregnancy rates with cycle intention to conceive ranged from 88.0% to 89.8%, and cumulative 13-cycle pregnancy rates with cycle intention to avoid ranged from 29.1% to 35.3%. In multivariate analysis, baseline motivations and intentions for pregnancy within 2 years were strongly correlated with the likelihood of pregnancy, more so than cycle intentions. The findings suggest that in some populations using natural family planning, baseline motivations and intentions may be more strongly related to pregnancy rates than cycle intentions. Our findings also highlight essential elements for evaluating correct use, including complete recording of intercourse and its timing.
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.
The uses of cervical mucus and basal body temperature as indicators of return to fertility postpartum have resulted in high unintended pregnancy rates. In 2013, a study found that when women used urine hormone signs in a postpartum/breastfeeding protocol this resulted in fewer pregnancies. To improve the original protocol's effectiveness, three revisions were made: (1) women were to increase the number of days tested with the Clearblue Fertility Monitor, (2) an optional second luteinizing hormone test could be done in the evening, and (3) instructions were given to manage the beginning of the fertile window for the first six cycles postpartum. The purpose of this study was to determine the correct and typical use effectiveness rates to avoid pregnancy in women who used a revised postpartum/breastfeeding protocol. A cohort review of an established data set from 207 postpartum breastfeeding women who used the protocol to avoid pregnancy was completed using Kaplan-Meier survival analysis. Total pregnancy rates that included correct and incorrect use pregnancies were eighteen per one hundred women over twelve cycles of use. For the pregnancies that met a priori criteria, the correct use pregnancy rates were two per one hundred over twelve months and twelve cycles of use and typical use rates were four per one hundred women at twelve cycles of use. The protocol had fewer unplanned pregnancies than the original, however, the cost of the method increased.