Menstrual Cycle

The menstrual cycle is the monthly hormonal cycle a female’s body goes through to prepare for pregnancy. Your menstrual cycle is counted from the first day of your period up to the first day of your next period. Your hormone levels (estrogen and progesterone) usually change throughout the menstrual cycle and can cause menstrual symptoms.

Source: https://www.womenshealth.gov/menstrual-cycle/your-menstrual-cycle

Video: https://www.youtube.com/watch?v=vXrQ_FhZmos