What is the Menstrual Cycle ?

Original Sources :

• Cleveland Clinic — The Menstrual Cycle
  https://my.clevelandclinic.org/health/articles/10132-menstrual-cycle

• The Lancet Global Women’s Health — Hormonal regulation and reproductive health
  https://www.thelancet.com/journals/lanogw/article/PIIS3050-5038(25)00001-9/fulltext

• NHS — Periods: fertility in the menstrual cycle
  https://www.nhs.uk/conditions/periods/fertility-in-the-menstrual-cycle/

• StatPearls / NCBI — Physiology, Menstrual Cycle
  https://www.ncbi.nlm.nih.gov/books/NBK500020/