There are quite a lot of different hormones and other factors that can contribute to period pain. Research has shown the most significant contributor is a type of hormone called prostaglandins, especially one particular type of prostaglandin called PGF2a. This hormone is stored in the walls of the cells that make up the lining of your uterus. This lining is what gets ‘shed’ each month as your period. When the lining starts to break down at the start of your period, the PGF2a that is in the cells gets released.

When PGF2a gets released it causes the characteristic ‘cramping’ feeling many individuals get when having period pain. PGF2a is so effective in stimulating these cramps or contractions that synthetic versions of PGF2a are used to help start labour.

PGF2a also gets absorbed into your blood stream, and this causes most of the other symptoms you get just before or during your period, such as headaches and breast tenderness.

Most people with primary dysmenorrhea have high levels of PGF2a in their menstrual blood (the blood that comes out during your period). These levels go up and down and this usually corresponds to the amount of pain felt. However, not all people with period pain have high levels of PGF2a and some research is continuing into what might cause period pain in these individuals.