Pearson, J. T., Chelstowska, M., Rowland, S. P., Benhar, E., Kopp-Kallner, H., Berglund Scherwitzl, E., Acuna, J., Gemzell Danielsson, K., & Scherwitzl, R. (2021). Contraceptive Effectiveness of an FDA-Cleared Birth Control App: Results from the Natural Cycles U.S. Cohort. Journal of women's health (2002), 30(6), 782-788. https://doi.org/10.1089/jwh.2020.8547
Pearson JT, Chelstowska M, Rowland SP, Benhar E, Kopp-Kallner H, Berglund Scherwitzl E, et al. Contraceptive Effectiveness of an FDA-Cleared Birth Control App: Results from the Natural Cycles U.S. Cohort. J Womens Health (Larchmt). 2021;30(6):782-788. doi:10.1089/jwh.2020.8547
Pearson, J. T., et al. "Contraceptive Effectiveness of an FDA-Cleared Birth Control App: Results from the Natural Cycles U.S. Cohort." Journal of women's health (2002), vol. 30, no. 6, 2021, pp. 782-788.
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Natural Cycles Nordic AB, Stockholm, Sweden056hm0802
Natural Cycles USA Corp, New York, New York, USA.
Khalifa University of Science and Technology05hffr360
Digital fertility awareness-based methods of birth control are an attractive alternative to hormonal or invasive birth control for modern women. They are also popular among women who may be planning a pregnancy over the coming years and wish to learn about their individual menstrual cycle. The aim of this study was to assess the effectiveness of the Natural Cycles app at preventing pregnancy for a cohort of women from the United States and to describe the key demographics of current users of the app in such a cohort.
Materials and Methods
This prospective real-world cohort study included users who purchased an annual subscription to prevent pregnancy. Demographics were assessed through answers to in-app questionnaires. Birth control effectiveness estimates for the entire cohort were calculated using 1-year pearl index (PI) and 13-cycle cumulative pregnancy probability (Kaplan-Meier life table analysis).
Results
The study included 5879 women who contributed an average of 10.5 months of data for a total of 5125 woman-years of exposure. The average user was 30 years old with a body mass index of 24 and reported being in a stable relationship. With typical use, the app had a 13-cycle cumulative pregnancy probability of 7.2% and a 1-year typical use PI of 6.2. When the app was used under perfect use, the PI was 2.0.
Conclusions
The data presented in this study give insights into the cohort of women using this app in the United States, and provide country-specific effectiveness estimates. The contraceptive effectiveness of the app was in line with previously published figures from Natural Cycles (PI of seven for typical use and two for perfect use).
Ecochard R et al., 2024·Fertil Steril·Free to read
To study whether the menstrual cycle has a circaseptan (7 days) rhythm and whether it is associated with the lunar cycle (also defined as the synodic month, it is the cycle of the phases of the Moon as seen from Earth, averaging 29.5 days in length).
Cross-sectional study. A total of 35,940 European and North American women aged 18-40 years. Exposure: Data were collected in real-life conditions. No intervention was performed. The onset of menstruation was assessed in prospectively measured menstrual cycles (311,064 cycles) over 3 full years (2019-2021). Associations were calculated between the onset of menstruation and the day of the week, and between the onset of menstruation and the lunar phase. In this large data set, a circaseptan (7-day) rhythmicity of menstruation was observed, with a peak (acrophase) of menstrual onset on Thursdays and Fridays. This circaseptan rhythm was observed in every age group, in every phase of the lunar cycle, and in all seasons. This feature was most pronounced for cycle durations between 27 and 29 days. In winter, the circaseptan rhythm was found in cycles of 27-29 days, but not in other cycle lengths. A circalunar rhythm was also statistically significant, but not as clearly defined as the circaseptan rhythm. The peak (acrophase) of the circalunar rhythm of menstrual onset varied according to the season. In addition, there was a small but statistically significant interaction between the circaseptan rhythm and the lunar cycle. Although relatively small in amplitude, the weekly rhythm of menstruation was statistically significant. Menstruation occurs more often on Thursdays and Fridays than on other days of the week. This is particularly true for women whose cycles last between 27 and 29 days. Circalunar rhythmicity was also statistically significant. However, it is less pronounced than the weekly rhythm.
Niemeyer Hultstrand J et al., 2022·Lancet Reg Health Eur·Free full text on PubMed Central
Evidence on a possible association between newer hormonal contraceptives (HC) and risk of breast cancer remains inconclusive, especially as concerns progestogen-only methods. In this nationwide prospective cohort study, all Swedish women aged 15-34 at study start on January 1(st) 2005, or who turned 15 years during the study period, were followed until December 31(st) 2017. Using information from seven National Registers, we assessed the risk ratio of developing breast cancer and breast cancer in situ in relation to different HC using Poisson regression. We adjusted the analyses for several known confounders of breast cancer. Findings: This cohort included 1.5 million women providing more than 14 million person-years. During the study period, 3842 women were diagnosed with breast cancer. Compared with never users of any HC, we found no increased risk of developing breast cancer among current users of any combined HC, IRR 1.03 (0.91-1.16), whereas current users of progestogen-only methods had an increased risk of developing breast cancer, IRR 1.32 (1.20-1.45). Across all types of HC, the risk of developing breast cancer appeared to be highest the first five years of use (combined HC IRR 1.39 (1.14-1.69); progestogen-only methods IRR 1.74 (1.44-2.10). The risk disappeared ten years after the women stopped using HC. The absolute risk of breast cancer per 100,000 women-years was 22.4 for never users, 10.9 for current users of combined HC, and 29.8 for current users of progestogen-only methods. Interpretation: Current use of progestogen-only methods is associated with a small increased risk of developing breast cancer, whereas we could only detect an increased risk among users of combined HC during the first five years of use. This may partly be explained by a selective prescription of progestogen-only methods to women with risk factors for breast cancer, like smoking or obesity. As the absolute risk of breast cancer was small, the many health benefits associated with HC must also be taken into account in contraceptive counselling. This study was funded by the Swedish Cancer Society and by the Uppsala County Council, the Faculty of Medicine at Uppsala University.
Edelman A et al., 2022·Obstetrics and gynecology·Free full text on PubMed Central
To assess whether coronavirus disease 2019 (COVID-19) vaccination is associated with changes in cycle or menses length in those receiving vaccination as compared with an unvaccinated cohort. We analyzed prospectively tracked menstrual cycle data using the application "Natural Cycles." We included U.S. residents aged 18-45 years with normal cycle lengths (24-38 days) for three consecutive cycles before the first vaccine dose followed by vaccine-dose cycles (cycles 4-6) or, if unvaccinated, six cycles over a similar time period. We calculated the mean within-individual change in cycle and menses length (three prevaccine cycles vs first- and second-dose cycles in the vaccinated cohort, and the first three cycles vs cycles four and five in the unvaccinated cohort). We used mixed-effects models to estimate the adjusted difference in change in cycle and menses length between the vaccinated and unvaccinated cohorts. We included 3,959 individuals (vaccinated 2,403; unvaccinated 1,556). Most of the vaccinated cohort received the Pfizer-BioNTech vaccine (55%) (Moderna 35%, Johnson & Johnson/Janssen 7%). Overall, COVID-19 vaccine was associated with a less than 1-day change in cycle length for both vaccine-dose cycles compared with prevaccine cycles (first dose 0.71 day-increase, 98.75% CI 0.47-0.94; second dose 0.91, 98.75% CI 0.63-1.19); unvaccinated individuals saw no significant change compared with three baseline cycles (cycle four 0.07, 98.75% CI -0.22 to 0.35; cycle five 0.12, 98.75% CI -0.15 to 0.39). In adjusted models, the difference in change in cycle length between the vaccinated and unvaccinated cohorts was less than 1 day for both doses (difference in change: first dose 0.64 days, 98.75% CI 0.27-1.01; second dose 0.79 days, 98.75% CI 0.40-1.18). Change in menses length was not associated with vaccination. Coronavirus disease 2019 (COVID-19) vaccination is associated with a small change in cycle length but not menses length.
Favaro C et al., 2021·J Womens Health (Larchmt)·Free full text on PubMed Central
Time to pregnancy (TTP) is a biomarker of fecundability and has been associated with behavioral and environmental characteristics; however, these associations have not been examined in a large population-based sample of application (app) users. This observational study followed 5,376 women with an age range of 18 to 45 years who used an app to identify their fertile window. We included women who started trying to conceive between September 30, 2017 and August 31, 2018. TTP was calculated as the number of menstrual cycles from when the user switched to "Plan" mode up to and including the cycle in which they logged a positive pregnancy test. We examined associations with several characteristics, including age, gravidity, body mass index, cycle length and cycle length variation, frequency of sexual intercourse, and temperature measuring frequency. Discrete time fecundability models were used to estimate fecundability odds ratios. For the complete cohort the 6-cycle and 12-cycle cumulative pregnancy probabilities were found to be 61% (95% confidence interval [CI]: 59-62) and 74% (95% CI: 73-76), respectively. The median TTP was four cycles. The highest fecundability was associated with an age of less than 35 years, with cycle length variation <5 days and logging sexual intercourse on at least 20% of days added (the proportion of days in which intercourse was logged) (11.5% [n = 613] of entire sample). This group achieved a 6and 12-cycle cumulative pregnancy probability of 88% (95% CI: 85-91) and 95% (95% CI: 94-97), respectively, and a TTP of 2 cycles. Natural Cycles was an effective method of identifying the fertile window and a noninvasive educational option for women planning a pregnancy. Women under age 35 with regular cycles showed a high pregnancy rate.
Pearson JT et al., 2021·Eur J Contracept Reprod Health Care·Free to read
Digital fertility awareness-based contraception offers an alternative choice for women who do not wish to use hormonal or invasive methods. The aim of this study was to investigate the key demographics of current users of the Natural Cycles app and assess the contraceptive outcomes of women preventing pregnancy in a UK cohort of women. This was a real world observational prospective observational study. The typical-use effectiveness of the method was calculated using both 13-cycle cumulative probability of pregnancy (life table analysis) and Pearl Index for the entire study cohort. Perfect-use PI was calculated using data from cycles where sexual intercourse during the fertile window was marked as protected and no unprotected sex was recorded on fertile days. 12,247 women were included in the study and contributed an average of 9.9 months of data for a total of 10,066 woman years of exposure. The mean age of the cohort was 30, mean BMI 23.4, the majority were in a stable relationship (83.2%) and had a university degree or higher (83%). The one year typical use, PI was 6.1 (95% CI: 5.6, 6.6) and with perfect-use was 2.0 (95% CI: 1.3, 2.8). 13 cycle pregnancy probability was 7.1%. This is the first study which describes the use of a digital contraceptive by women in the UK. It describes the demographics of users and how they correlate with the apps effectiveness at preventing pregnancy.
Jennings V et al., 2019·Eur J Contracept Reprod Health Care·Free to read
Dynamic Optimal Timing (Dot) is a smartphone application (app) that estimates the menstrual cycle fertile window based on the user's menstrual period start dates. Dot uses machine learning to adapt to cycles over time and informs users of 'low' and 'high' fertility days. We investigated Dot's effectiveness, calculating perfectand typical-use failure rates. This prospective, 13 cycle observational study (ClinicalTrials.gov NCT02833922) followed 718 women who were using Dot to prevent pregnancy. Participants contributed 6616 cycles between February 2017 and October 2018, providing data on menstrual period start dates, daily sexual activity and prospective intent to prevent pregnancy. We determined pregnancy through participant-administered urine pregnancy tests and/or written or verbal confirmation. We calculated perfectand typical-use failure rates using multi-censoring, single-decrement life-table analysis, and conducted sensitivity, attrition and survival analyses. The perfect-use failure rate was calculated to be 1.0% (95% confidence interval [CI]: 0.9%, 2.9%) and the typical-use failure rate was 5.0% (95% CI: 3.4%, 6.6%) for women aged 18-39 (n = 718). Survival analyses identified no significant differences among age or racial/ethnic groups or women in different types of relationships. Attrition analyses revealed no significant sociodemographic differences, except in age, between women completing 13 cycles and those exiting the study earlier. Dot's effectiveness is within the range of other user-initiated contraceptive methods.
Duane M et al., 2016·J Am Board Fam Med·Free to read
In recent years there has been an explosion in the development of medical apps, with more than 40,000 apps now available. Nearly 100 apps allow women to track their fertility and menstrual cycles and can be used to avoid or achieve pregnancy. Apps offer a convenient way to track fertility biomarkers. However, only some use evidence-based fertility awareness-based methods (FABMs), which with ideal use have rates of effectiveness similar to those of commonly used forms of hormonal birth control. Since having a baby or preventing a pregnancy are important responsibilities, it is critical that women and couples have access to reliable, evidence-based apps that allow them to accurately track their fertility. We developed a tool to evaluate and rate fertility apps. This tool is specifically designed to help couples avoid pregnancy. Results showed that the majority of fertility apps are not based on evidence-based FABMs or include a disclaimer discouraging use for avoiding pregnancy. However, at least 1 app in each FABM category (except symptohormonal methods) had a perfect score on accuracy. Relying solely on an app to use an FABM, without appropriate training in the method, may not be sufficient to prevent pregnancy.
Jennings VH et al., 2019·Contraception·Free to read
To assess six-cycle perfect and typical use efficacy of Dynamic Optimal Timing (Dot), an algorithm-based fertility app that identifies the fertile window of the menstrual cycle using a woman's period start date and provides guidance on when to avoid unprotected sex to prevent pregnancy.
We are conducting a prospective efficacy study following a cohort of women using Dot for up to 13 cycles. Study enrollment and data collection are being conducted digitally within the app and include a daily coital diary, prospective pregnancy intentions and sociodemographic information. We used data from the first six cycles to calculate life-table failure rates.
We enrolled 718 women age 18-39 years. Of the 629 women 18-35 years old, 15 women became pregnant during the first six cycles for a typical use failure rate of 3.5% [95% CI 1.7-5.2]. All pregnancies occurred with incorrect use, so we did not calculate a perfect use failure rate.
These findings are promising and suggest that the 13-cycle results will demonstrate high efficacy of Dot.
While final 13-cycle efficacy results are forthcoming, 6-cycle results suggest that Dot's guidance provides women with useful information for preventing pregnancy.
Fertility Awareness › Effectiveness › Typical and Perfect Use
Jack T Pearson, Simon P Rowland, Eleonora Benhar, Juan Acuna, Elina Berglund Scherwitzl, Magda Chelstowska, Helena Kopp Kallner, Raoul Scherwitzl
John Pearson, J Pearson, S Rowland, E Benhar, J Acuna, E Scherwitzl, M Chelstowska, H Kallner, R Scherwitzl
PMID 33370220 33370220 DOI 10.1089/jwh.2020.8547 10.1089/jwh.2020.8547 Pearson et al. 2020, Pearson 2020
Cite this article
Pearson, J. T., Chelstowska, M., Rowland, S. P., Benhar, E., Kopp-Kallner, H., Berglund Scherwitzl, E., Acuna, J., Gemzell Danielsson, K., & Scherwitzl, R. (2021). Contraceptive Effectiveness of an FDA-Cleared Birth Control App: Results from the Natural Cycles U.S. Cohort. Journal of women's health (2002), 30(6), 782-788. https://doi.org/10.1089/jwh.2020.8547
Pearson JT, Chelstowska M, Rowland SP, Benhar E, Kopp-Kallner H, Berglund Scherwitzl E, et al. Contraceptive Effectiveness of an FDA-Cleared Birth Control App: Results from the Natural Cycles U.S. Cohort. J Womens Health (Larchmt). 2021;30(6):782-788. doi:10.1089/jwh.2020.8547
Pearson, J. T., et al. "Contraceptive Effectiveness of an FDA-Cleared Birth Control App: Results from the Natural Cycles U.S. Cohort." Journal of women's health (2002), vol. 30, no. 6, 2021, pp. 782-788.
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