Accepted for/Published in: Journal of Medical Internet Research
Date Submitted: Mar 12, 2020
Date Accepted: Apr 20, 2020
Date Submitted to PubMed: May 22, 2020
Menstrual Cycle Length And Patterns In A Global Cohort Of Women Using A Mobile Phone App: A retrospective cohort study
ABSTRACT
Background:
There is increasing information characterizing menstrual cycle length in healthy women, but less information on the potential differences across lifestyle variables.
Objective:
The primary aim of this study is to describe differences in menstrual cycle length, variability, and menstrual phase, across women with different age and BMI. We also report on demographic and lifestyle characteristics across median cycle length.
Methods:
The analysis was run based on the aggregated anonymized dataset from a menstrual cycle tracker and ovulation calendar that covers all phases of the reproductive cycle. Self-reported information is documented including demographics, menstrual flow and cycle length, ovulation information, and reproductive health and diseases. Data from women aged 18+ years and who had logged at least 3 cycles (i.e. 2 completed cycles and 1 current cycle) was included (1,579,819 women).
Results:
Of the 1.5 million users, nearly half (n=638,683, 40.4%) were aged 18-24 y. Just over half of those reporting BMI were in the normal range (18.5-24.9 kg/m2; n=202,420; 56.8%) and one third had an overweight/obese BMI (>25 kg/m2, n=120,983; 33.9%). Sixteen percent of women had a median 28 d length (n=257,889). There was a higher percentage of women aged 40+ y who had a 27 d median cycle length than those aged 18-24 y (18.5% vs 9.6%), but a lower percentage with a median 29 d cycle length (8.8% vs. 12.5%). There was a higher number of cycles with short luteal phases in younger women, whereas there was a higher number of cycles with longer luteal phases in women aged 40 years and over. Median menstrual cycle length, and length of follicular and luteal phases were not remarkably different with increasing BMI, except for the heaviest women at a BMI 50+ kg/m2.
Conclusions:
We provide extensive, worldwide evidence, on the characteristics of women and their menstrual cycle length and patterns across different age and BMI groups. This information is necessary to support the updating of current clinical guidelines around menstrual cycle length and patterns for clinical use in fertility programs. Clinical Trial: NONE
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