Real-World Menstrual Cycle Characteristics of More Than 600,000 Menstrual Cycles
First published: 2019
Brief summary
Large-scale analysis of over 600,000 ovulatory cycles from a fertility-tracking app finds a mean cycle length of 29.3 days, with mean follicular phase of 16.9 days and luteal phase of 12.4 days, and documents how cycle length shortens with age.
Article
Real-World Menstrual Cycle Characteristics of More Than 600,000 Menstrual Cycles is a peer-reviewed journal article published by npj Digital Medicine (Nature) in 2019. It is a large-scale analysis of over 600,000 ovulatory cycles from a fertility-tracking app that finds a mean cycle length of 29.3 days, with mean follicular phase of 16.9 days and luteal phase of 12.4 days, and documents how cycle length shortens with age.
The analysis focuses on mean 29.3 days (infradian). It also considers follicular phase 16.9 days, luteal phase 12.4 days. The data source is 612,613 cycles from 124,648 users of the Natural Cycles app. This gives the cycle claim a specific numerical and evidential setting rather than presenting periodicity only as a visual impression.
The authors analyse 612,613 ovulatory cycles with a mean length of 29.3 days from 124,648 users. Mean cycle length decreased by 0.18 days per year of age from 25 to 45 years. The interpretation is strongest when sample selection, age, physiology, measurement error and individual variability are accounted for.
For cycles researchers, the article brings together menstrual cycle length, ovulation, follicular phase, fertility tracking. It is relevant to biological cycle research because living systems contain interacting clocks and rhythms whose periods vary with physiology, age, environment and measurement method.
Because it is a peer-reviewed journal article, the article is a strong starting point for discussion in the Biology & Human Biology forum, although its conclusions should still be compared with later replications and updated datasets.
Source details and credits
- Source / publisher: npj Digital Medicine (Nature)
- Source type: Peer-reviewed journal article
- URL type: WWW
- Credits: npj Digital Medicine (Nature)
- URL: https://www.nature.com/articles/s41746-019-0152-7