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How do estrogen and progesterone levels change near the end of a menstrual cycle?

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Detailed cross-sectional illustration of a human ovary showing the stages of follicle development, ovulation, and corpus luteum formation, with labeled structures including primordial, primary, secondary, and mature follicles, a ruptured follicle releasing an ovum, and corpus luteum and albicans. An inset at the bottom shows the ovary's location in the female reproductive system. — ovary The steps of ovulation, beginning with a dormant primordial follicle that grows and matures and is eventually released from the ovary into the fallopian tube.

Near the end of the menstrual cycle, the corpus luteum—the structure that produces hormones following ovulation—begins to degenerate, a process known as luteolysis.1

As the corpus luteum becomes inactive, the production of both estrogen and progesterone decreases significantly. This decline in hormone levels causes the constriction of uterine arteries, which interrupts the supply of oxygen and nutrients to the endometrium, leading to the shedding of the uterine lining during menstruation. Additionally, these falling hormone concentrations are associated with the symptoms of premenstrual syndrome, such as fluid retention and changes in mood.12