To test the efficacy of the TwoDay Method, a new fertility awareness-based method of family planning that provides women with simple instructions to identify the days each cycle when they are most likely to become pregnant. Users avoid unprotected intercourse on days when cervical secretions are present on that day or on the day before, to prevent pregnancy.
Design
Prospective, nonrandomized, multicenter study.
Setting
Five culturally diverse sites in Guatemala, Peru, and the Philippines. PATIENT(S): Four hundred fifty women, aged 18-39 years, wishing to use a fertility awareness-based method to prevent or delay pregnancy. INTERVENTION(S): Study participants were followed for up to 13 cycles of method use. MAIN OUTCOME MEASURE(S): Life table pregnancy rate. RESULT(S): The first-year pregnancy rate was 3.5 (pregnancies per 100 women/years) with correct use of the method (pregnancies and cycles with no intercourse on identified fertile days), 6.3 with use of a backup method on the fertile days, and 13.7 including all cycles and all pregnancies in the analysis. CONCLUSION(S): The TwoDay Method offers a valuable addition to the services that reproductive health and other programs can offer. Its efficacy compares well with that of other coitus-dependent family-planning methods; it is easy to teach, learn, and use; and it can address the need of women for simple, accurate instructions for identifying their fertile days.
TwoDay Method fertility awareness cervical secretions efficacy, TwoDay Method family planning pregnancy rate multicenter study, Jennings Sinai Arévalo TwoDay Method cervical mucus, fertility awareness based method correct use pregnancy rate, cervical secretions monitoring natural family planning efficacy, TwoDay Method Guatemala Peru Philippines prospective study, coitus dependent family planning method comparison efficacy, fertility awareness method simple instructions fertile days, natural family planning cervical mucus observation pregnancy prevention, life table pregnancy rate fertility awareness TwoDay Method
PMID 15482764 15482764 DOI 10.1016/j.fertnstert.2004.03.040 10.1016/j.fertnstert.2004.03.040 Jennings et al. 2004, Jennings 2004
Cite this article
Arévalo, M., Jennings, V., Nikula, M., & Sinai, I. (2004). Efficacy of the new TwoDay Method of family planning. Fertility and sterility, 82(4), 885-892. https://doi.org/10.1016/j.fertnstert.2004.03.040
Arévalo M, Jennings V, Nikula M, Sinai I. Efficacy of the new TwoDay Method of family planning. Fertil Steril. 2004;82(4):885-892. doi:10.1016/j.fertnstert.2004.03.040
Arévalo, M., et al. "Efficacy of the new TwoDay Method of family planning." Fertility and sterility, vol. 82, no. 4, 2004, pp. 885-892.
To develop a new method for estimating the effectiveness of emergency contraception (EC) by using information about previous menstrual cycle length, accounting for the variation in the day of ovulation within the menstrual cycle, and comparing the validity of the new and previous methods. METHOD(S): Secondary analysis of a data set with a biological marker of ovulation and its distribution in the cycle. Based on a sample of cycles with known length and a known biological marker of ovulation, we simulated trials of predetermined EC effectiveness and then calculated estimates of EC effectiveness based on old and new methods. RESULT(S): Under some conditions, all methods produced biased estimates of effectiveness with simulated trials, especially when the actual effectiveness was low. The systematic bias was minimized with the new method. The new method was robust with regard to the distribution of the day of intercourse in women presenting for EC. CONCLUSION(S): Future studies of EC effectiveness should consider both the uncertainty in predicting the day of ovulation and previous cycle length. Our estimates of daily fecundity should be replicated with other data sets.
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.