The natural cause of low AMH levels can be age or gender in males and females. But there are some other conditions as well that lead to the decrease in AMH level.
The common low AMH causes are;
Endometriosis
It is a painful disorder of the reproductive system. A condition in which the tissues generally found inside your uterus (womb) grows outside the uterus is called endometriosis. In this case, the inflammation and scar tissue damage the ovaries and fallopian tubes, resulting in low levels of AMH.
Genetics factor
Changes in genes, i.e., a positive history of low AMH in families, can also affect your level of AMH.
Polycystic ovary syndrome (PCOS)
PCOS is the most common female reproductive disorder. In this, your ovary produced an abnormal amount of male sex hormone androgens. The number of small cysts formed in the ovaries can affect your AMH levels.
Autoimmune diseases
In this disease, your immune system attacks your healthy cells and thus damages the healthy egg cells, which lowers the AMH level.
Chemotherapy
If one is having active cancer and undergoing chemotherapy, it increases the risk of damaging healthy follicles of the ovary, leading to a low number of AMH.
Lifestyle changes
Some lifestyle factors can also affect the level of AMH in your body, like excessive smoking, environmental pollution, obesity, vitamin D deficiency, etc.