A period is a flow of blood from the lining of the uterus, lasting for a few days and occurring sexually mature women who are not pregnant at intervals of about one lunar month until the menopause. The medical term for painful menstrual cycle is dysmenorrheal and this occurs in women who experience cramping pain in the abdomen. This can start from 1 – 2 days before your period begins and it may last for up to 4 days. Women trigger uterine contractions and these expels uterine lining when menstruating. Women who sometimes have higher levels of prostaglandins have more vigorous cramps and will experience more pains. But a woman produces different levels prostaglandin with each cycle and even throughout are ovulating span. So the pains she feels always varies.