further work

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@@ -2000,3 +2000,45 @@ Conclusions: For women interested in maximizing the chances of pregnancy, wrist
 	langid = {english},
 	file = {Snapshot:/home/alex/Zotero/storage/HNFFJPSN/kegg.tech.html:text/html},
 }
+
+@article{ecochard_menstrual_2024,
+	title = {The menstrual cycle is influenced by weekly and lunar rhythms},
+	volume = {121},
+	issn = {00150282},
+	url = {https://linkinghub.elsevier.com/retrieve/pii/S0015028223020769},
+	doi = {10.1016/j.fertnstert.2023.12.009},
+	abstract = {Objective: To study whether the menstrual cycle has a circaseptan (7 days) rhythm and whether it is associated with the lunar cycle (also defined as the synodic month, it is the cycle of the phases of the Moon as seen from Earth, averaging 29.5 days in length). Design: Cross-sectional study. Subjects: A total of 35,940 European and North American women aged 18–40 years. Exposure: Data were collected in real-life conditions. Intervention: No intervention was performed. Main Outcome Measure: The onset of menstruation was assessed in prospectively measured menstrual cycles (311,064 cycles) over 3 full years (2019–2021). Associations were calculated between the onset of menstruation and the day of the week, and between the onset of menstruation and the lunar phase.
+Results: In this large data set, a circaseptan (7-day) rhythmicity of menstruation was observed, with a peak (acrophase) of menstrual onset on Thursdays and Fridays. This circaseptan rhythm was observed in every age group, in every phase of the lunar cycle, and in all seasons. This feature was most pronounced for cycle durations between 27 and 29 days. In winter, the circaseptan rhythm was found in cycles of 27–29 days, but not in other cycle lengths. A circalunar rhythm was also statistically significant, but not as clearly defined as the circaseptan rhythm. The peak (acrophase) of the circalunar rhythm of menstrual onset varied according to the season. In addition, there was a small but statistically significant interaction between the circaseptan rhythm and the lunar cycle.
+Conclusion: Although relatively small in amplitude, the weekly rhythm of menstruation was statistically significant. Menstruation occurs more often on Thursdays and Fridays than on other days of the week. This is particularly true for women whose cycles last between 27 and 29 days. Circalunar rhythmicity was also statistically significant. However, it is less pronounced than the weekly rhythm. (Fertil {SterilÒ} 2024;121:651-9. Ó2023 by American Society for Reproductive Medicine.)},
+	pages = {651--659},
+	number = {4},
+	journaltitle = {Fertility and Sterility},
+	author = {Ecochard, René and Leiva, Rene and Bouchard, Thomas P. and Van Lamsweerde, Agathe and Pearson, Jack T. and Stanford, Joseph B. and Gronfier, Claude},
+	urldate = {2025-07-03},
+	date = {2024-04},
+	langid = {english},
+	file = {PDF:/home/alex/Zotero/storage/T6DNB4M9/Ecochard et al. - 2024 - The menstrual cycle is influenced by weekly and lunar rhythms.pdf:application/pdf},
+}
+
+@article{li_menstrual_2023,
+	title = {Menstrual cycle length variation by demographic characteristics from the Apple Women’s Health Study},
+	volume = {6},
+	issn = {2398-6352},
+	url = {https://www.nature.com/articles/s41746-023-00848-1},
+	doi = {10.1038/s41746-023-00848-1},
+	abstract = {Abstract
+            
+              Menstrual characteristics are important signs of women’s health. Here we examine the variation of menstrual cycle length by age, ethnicity, and body weight using 165,668 cycles from 12,608 participants in the {US} using mobile menstrual tracking apps. After adjusting for all covariates, mean menstrual cycle length is shorter with older age across all age groups until age 50 and then became longer for those age 50 and older. Menstrual cycles are on average 1.6 (95\%{CI}: 1.2, 2.0) days longer for Asian and 0.7 (95\%{CI}: 0.4, 1.0) days longer for Hispanic participants compared to white non-Hispanic participants. Participants with {BMI} ≥ 40 kg/m
+              2
+              have 1.5 (95\%{CI}: 1.2, 1.8) days longer cycles compared to those with {BMI} between 18.5 and 25kg/m
+              2
+              . Cycle variability is the lowest among participants aged 35–39 but are considerably higher by 46\% (95\%{CI}: 43\%, 48\%) and 45\% (95\%{CI}: 41\%, 49\%) among those aged under 20 and between 45–49. Cycle variability increase by 200\% (95\%{CI}: 191\%, 210\%) among those aged above 50 compared to those in the 35–39 age group. Compared to white participants, those who are Asian and Hispanic have larger cycle variability. Participants with obesity also have higher cycle variability. Here we confirm previous observations of changes in menstrual cycle pattern with age across reproductive life span and report new evidence on the differences of menstrual variation by ethnicity and obesity status. Future studies should explore the underlying determinants of the variation in menstrual characteristics.},
+	pages = {100},
+	number = {1},
+	journaltitle = {npj Digit. Med.},
+	author = {Li, Huichu and Gibson, Elizabeth A. and Jukic, Anne Marie Z. and Baird, Donna D. and Wilcox, Allen J. and Curry, Christine L. and Fischer-Colbrie, Tyler and Onnela, Jukka-Pekka and Williams, Michelle A. and Hauser, Russ and Coull, Brent A. and Mahalingaiah, Shruthi},
+	urldate = {2025-07-04},
+	date = {2023-05-29},
+	langid = {english},
+	file = {PDF:/home/alex/Zotero/storage/9J5N6YIW/Li et al. - 2023 - Menstrual cycle length variation by demographic characteristics from the Apple Women’s Health Study.pdf:application/pdf},
+}