Personalised estimation of a woman’s most fertile days

Abstract

Objectives: We propose a new, personalised approach of estimating a woman’s most fertile days that only requires recording the first day of menses and can use a smartphone to convey this information to the user so that she can plan or prevent pregnancy.

Methods: We performed a retrospective analysis of two cohort studies (a North Carolina-based study and the Early Pregnancy Study [EPS]) and a prospective multicentre trial (World Health Organization [WHO] study). The North Carolina study consisted of 68 sexually active women with either an intrauterine device or tubal ligation. The EPS comprised 221 women who planned to become pregnant and had no known fertility problems. The WHO study consisted of 706 women from five geographically and culturally diverse settings. Bayesian statistical methods were used to design our proposed method, Dynamic Optimal Timing (DOT). Simulation studies were used to estimate the cumulative pregnancy risk.

Results: For the proposed method, simulation analyses indicated a 4.4% cumulative probability of pregnancy over 13 cycles with correct use. After a calibration window, this method flagged between 11 and 13 days when unprotected intercourse should be avoided per cycle. Eligible women should have cycle lengths between 20 and 40 days with a variability range less than or equal to 9 days.

Conclusions: DOT can easily be implemented by computer or smartphone applications, allowing for women to make more informed decisions about their fertility. This approach is already incorporated into a patent-pending system and is available for free download on iPhones and Androids.

Chinese abstract

目的：我们提出了一种新的个体化评估女性月经周期中最佳生育期的方法, 用户仅需将月经周期第一天的日期传送至智能手机即可计划或预防妊娠。

方法：我们进行了两个队列研究（北卡罗来纳研究及早期妊娠研究[Early Pregnancy Study, EPS]）的回顾性分析和一项前瞻性多中心研究（世卫组织[World Health Organization, WHO]研究）。北卡罗来纳研究包括68名有宫内节育器或输卵管结扎的性活跃女性。EPS研究包括221名计划怀孕且无生殖疾病的女性。WHO研究包括来自五个不同地域和文化的706名女性。使用贝叶斯统计法设计我们所提出的方法, 即动态最优时机（Dynamic Optimal Timing, DOT）。仿真模拟实验被用于估计累积妊娠风险。

结果：通过本文提出的方法, 模拟分析在13个正确使用的周期中指出了4.4%累积妊娠率。在校正期后, 此方法将每周期的第11至13天标记, 在此时期内应避免无保护性交。此方法适用于月经周期长度20至40天, 变异范围小于或等于9天的女性。

结论：DOT可以轻易通过电脑或智能手机应用软件实施, 使妇女在生育相关问题上做出更明智的决策。此方法已申请专利, 并可在iphone或安卓系统中免费下载。

Keywords:

• Fertility awareness
• health
• personalised medicine

View correction statement:

Correction to: Li et al., Personalised estimation of a woman’s most fertile days

Acknowledgements

We would like to thank the National Institute of Environmental Health Sciences (Research Triangle Park, NC, USA) for access to the data. We would also like to thank Cycle Technologies (Washington, DC, USA) and the United States Agency for International Development (Washington, DC, USA) for their support in this work.

Disclosure statement

Cycle Technologies provided funding for analyses and helped with the design of the study and preparation of the report.