Risk factors:

Studies have determined smoking causes menopause to occur 1-2yrs earlier for women.

Genetics

Chemotherapy along with pelvic radiation

Women that have epilepsy are known to have a higher risk of premature menopause.

Hysterectomy- removal of the uterus oophorectomy- removal of one ovary
Bilateral oophorectomy- both ovaries removed.

Turner syndrome- this is when the ovaries don't function right due to a chromosome defect.

Autoimmune diseases: rheumatoid arthritis is one and another thyroid disease.