Endometriosis
Where the cells that normally line your womb start to grow in other places such as the ovaries, this can cause intense pain when the cells shed.
Fibroids
These non-cancerous tumours grow in the womb or around the womb and can make your periods very heavy and painful.
Adenomyosis
This is where the tissue that is lining the womb begins to grow within the muscular womb wall and can make periods very painful.
Pelvic Inflammation Disease
The womb, fallopian tubes and ovaries all become infected with bacteria which makes them inflamed, causing painful periods.
Related guide
Other articles around women's health, including menopause and pelvic health, written with the support of the Lady Garden Foundation.