Jennings, V., Nikula, M., Sinai, I., & Arévalo, M. (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
Jennings V, Nikula M, Sinai I, Arévalo M. Efficacy of the new TwoDay Method of family planning. Fertil Steril. 2004;82(4):885-892. doi:10.1016/j.fertnstert.2004.03.040
Jennings, V., et al. "Efficacy of the new TwoDay Method of family planning." Fertility and Sterility, vol. 82, no. 4, 2004, pp. 885-892.
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TwoDay Method had 3.5 pregnancies per 100 women yearly, used correctly
A prospective, nonrandomized study of 450 women in Guatemala, Peru and the Philippines found the TwoDay Method had 3.5 pregnancies per 100 women a year with correct use. Correct use meant no intercourse on the days the method flags as fertile. Counting all cycles and all pregnancies, the first-year rate was 13.7 per 100 women.
Study at a glance, Prospective, nonrandomized, multicenter of 450 women: TwoDay Method: 3.5 pregnancies per 100 women a year with correct use. Source: Jennings V et al., 2004, PMID 15482764.
Key Findings
With correct use, meaning no intercourse on days the method flagged as fertile, 3.5 pregnancies occurred per 100 women/years in the first year (95% CI 1.44–5.52).
When cycles using condoms or withdrawal on fertile days were also counted, the rate was 6.3 (95% CI 3.61–8.81).
Counting every cycle and every pregnancy, the rate was 13.7 (95% CI 9.93–17.34).
The 450 women had 47 pregnancies during the study. Of these, 12 pregnancies (25.5%) occurred in cycles with no reported intercourse on the fertile days.
In all, 52.7% of the 450 women completed 13 cycles of method use. After the first cycle, 96.4% reported no problem detecting secretions.
Interpretation
The study followed 450 women ages 18 to 39 in Guatemala, Peru and the Philippines. All had a prior pregnancy and lived with a partner. Most women completed the full 13 cycles. After the first cycle, almost all reported no trouble spotting secretions. The authors note that some women may have under-reported sex on fertile days. They say this could make the true failure rate higher than the one reported here. The findings support larger studies of the TwoDay Method and other fertility awareness-based approaches.
RRM Context
Fertility awareness-based methods track cervical mucus to find the fertile window. This window is usually 6 days: the 5 days before ovulation plus the day of ovulation. The TwoDay Method asks one simple question: did mucus show up today or yesterday? Restorative reproductive medicine reads charted signs like these to understand a woman's cycles.
Our editorial summary of this paper, not the article's abstract.
Abstract
Objective
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.
Patients
Four hundred fifty women, aged 18-39 years, wishing to use a fertility awareness-based method to prevent or delay pregnancy.
Interventions
Study participants were followed for up to 13 cycles of method use.
Main Outcome Measures
Life table pregnancy rate.
Results
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.
Conclusions
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.
Clinician-reviewed comparison of fertility awareness-based methods (Billings, Creighton, Sensiplan, Marquette, Standard Days, apps). Every effectiveness figure cited and labeled by metric.
