Menstrual Cycle Heat Maps: Visualising menstrual cycle variability using hormone heat map arrays referenced to the ultrasound day of ovulation

Objective: There is considerable individual day-to-day variation within the menstrual cycle and between cycles in women. Average hormone curves inadequately describe the individual hormone patterns experienced by women. The present study applies a novel application of a statistical array (heat map) to demonstrate both individual and group menstrual cycle hormone variability. Design: Using pre-existing datasets, two cohorts of women were analysed using a statistical method to visualise quantitative hormonal variation. Subjects: In one cohort, 107 women contributed a total of 283 menstrual cycles and in the second cohort, 21 women contributed a total of 62 menstrual cycles. Exposure: Women collected first morning urine samples for analysis of estrone-3-glucuronide (E1G) and luteinizing hormone (LH) in both datasets. In the larger dataset, pregnanediol-3-alpha-glucuronide (PDG) and follicle-stimulating hormone (FSH) were also collected. Serial ultrasounds identified the precise day of ovulation in the larger dataset. In the smaller dataset, peak LH was used to identify the estimated day of ovulation. Outcome measure: The main outcome measure was identifying hormonal variability using hormone array heat maps. Conclusion: Heat maps were able to quickly show clustering of hormone patterns in the fertile window and on the day of ovulation. Individual differences were identified in rows on the heat map relative to the day of ovulation. This new tool to visually represent hormonal changes with heat maps identifies both individual and group variability of menstrual cycle hormones.