11/22/2025
Daily chronological progression of the menstrual cycle (DA1–DA8)
DA1: Menstruation begins, characterized by decreased estrogen (↓E), decreased progesterone (↓P), and increased follicle-stimulating hormone (↑FSH), signalling the start of the menstrual cycle.
DA2: Continued uterine bleeding occurs as follicle recruitment progresses, with rising FSH levels stimulating multiple follicle growth.
DA3: Bleeding diminishes as estrogen levels increase (↑Estrogen), leading to the proliferation and regeneration of the endometrial lining in preparation for potential pregnancy.
DA4: The early proliferative phase starts, marked by a further rise in estrogen (↑Estrogen), which promotes rapid endometrial cell division and thickening.
DA5: Menstrual bleeding ceases; estrogen levels peak significantly (↑↑Estrogen), completing the proliferative phase and preparing the endometrium for potential implantation.
DA6: The endometrial lining continues to thicken; serum FSH levels decrease (FSH ↓) due to negative feedback from rising estrogen, which stabilizes follicular development.
DA7: A dominant follicle emerges, secreting increased estrogen (↑Estrogen), which signals the hypothalamic-pituitary axis to modulate hormone release and support further maturation.
DA8: The mid-follicular phase features high estrogen levels, supporting ongoing follicular growth and preparing for ovulation by optimizing the ovarian environment.