Contraceptive Outcomes of the Natural Cycles Birth Control App: A Study of Canadian Women

Objective This study aimed to investigate the key demographics and evaluate the real-world contraceptive failure and continuation rates of the Natural Cycles app in a cohort of women from Canada. Methods This was a real-world, prospective cohort study. Demographics were assessed via in-app questionnaires. Contraceptive failure rates in typical and perfect use were calculated using the 13-cycle cumulative pregnancy probability (Kaplan-Meier survival analysis) and the one-year Pearl Index (PI). One-year continuation rates were estimated through survival analysis. Results The study included 8 '798 women who contributed an average of 9.2 months of data, amounting to a total of 7' 063 woman-years of exposure. The average user was 27.3 years old, had a body mass index of 24.6, and reported being in a stable relationship. With typical use, the app demonstrated a 13-cycle cumulative pregnancy probability of 4.8 [95% CI: 4.3, 5.4] and a Pearl Index of 4.3 [95% CI: 3.9, 4.8]. Under perfect use, the contraceptive failure rate was 2.3 [95% CI: 0.7, 3.9] for life table analysis and 1.7 [95% CI: 0.5, 2.8] for the 1-year PI. The contraceptive method's continuation rate after one year was 62.4%. Conclusions The data presented in this study offer valuable insights into the cohort of women using the Natural Cycles app in Canada and provide country-specific effectiveness estimates. The app's contraceptive effectiveness aligns with previously published data on Natural Cycles.