There are methods to ease them. Menstruation occurs once a month during the natural cycle in which the uterine lining is shed in mature females. It lasts from three to seven days long. Estrogen is released to stimulate the growth of the uterine lining. Then the pituitary gland releases a hormone to prepare the egg.
Progesterone is released which further increases the blood vessels in the uterus.
The egg is released during ovulation. If the egg is not fertilized the levels of progesterone and estrogen drop and menstruation occurs. The blood vessels are shed from the uterus during menstruation, the first day usually being the heaviest. Menstrual cramps usually occur on the first day of the menstruation cycle when the flow begins. Cramps can last for a couple of hours to a few days.