The menstrual cycle begins from the first day of a period and ends the day before the next period. Cycles vary between woman to woman, but the average is anywhere from 28-32 days and can even extend from 21 to 40 days. This all depends on lifestyle, hormones, underlying medical conditions, and a plethora of other factors. Every month, the uterus prepares for pregnancy by thickening up the uterine lining while the ovaries and pituitary gland in the brain secrete hormones like estrogen, luteinizing hormone (LH), and progesterone.
The menstrual cycle has 4 phases: the menstruation, follicular, ovulation, and luteal phase. Each is characterized by different dominating hormones: estrogen, progesterone, and LH. As each of these hormones increase and decrease in concentration, the body and mind experience strengths and weaknesses associated with each one.