Heredity. Heredity can also be a factor of pcod.  The mechanisms by which variants in the genes confer the  risk to PCOS and the nature of the genetic and physical interaction between the genetic elements underlying PCOS remain to be determined. Having a family history of PCOS can lead to pcos in females but there are no evidences to prove this theory.

Insulin resistance. Insulin hormone is produced by beta cells of pancreas. It maintains normal blood sugar levels by facilitating cellular glucose uptake,regulates carbohydrate ,lipid metabolism. If cells become resistant to the action of insulin, then blood sugar levels can increase. This can cause the body to make more insulin to try to bring down the blood sugar level.

Too much insulin can cause the body to make too much of the male hormone i.e androgens. It can interfere with the process of  ovulation, the process where egg i.e ovam  is released from the ovary. Insulin resistance can cause dark, patches of skin particularly on the cheeks,chin ,lower part of the neck, armpits, groin or under the breasts. Increased in  appetite and central obesity can occur.

High level of inflammation. In case of PCOS, females have high levels of other markers for inflammation like oxidative stress, inflammatory cytokines, and white blood cells i.e lymphocytes and monocytes. All of these factors are involved in the immune response and are also found during inflammation.

Excess male hormones. 

In PCOS there is a link between high testosterone levels which cause urinary urgency, urine incontinence, a need to urinate at night, bladder or pelvic pain .Excess androgen hormones can cause facial hair,infertility,anovulation,amenorrhea,reduce libido in females.

Improper nutrition:

Lack of proper nutrition,healthy diet can also cause hormonal fluctuation in females ans cause pcos.