N94: Pain and other conditions associated with female genital organs and menstrual cycle

N94.5: Secondary dysmenorrhoea

This lining of the uterus thickens at the start of each normal menstrual cycle. It is then expelled when you have your period. This process is controlled by various sex hormones.

Pain associated with menstrual periods can occur in the lower abdomen. It may also radiate to the back or thigh.

You did not have very much pain associated with your menstrual periods in the past, if at all. If such pain occurs in the course of life or gets more severe, then various conditions or physical changes can be to blame.