MedicineEndocrinologyPhysiologyReproductive BiologyReproductive EndocrinologyReproductive PhysiologyMenstrual CycleOvarian PhysiologyReproductive CyclesFemale Reproductive EndocrinologyFemale Reproductive PhysiologyHormonal Cycle VariabilityMenstrual Cycle DisturbancesMenstrual Cycle DynamicsMenstrual Cycle EndocrinologyMenstrual Cycle Regulation