Sperm count is less than 20 million / milliliter known as Low Sperm Count also called Oligospermia.

Normal Sperm Count: 40 million / milliliter to 120 million / milliliter

Causes of low Sperm Count:

1. Overheating, working in High temperature zone,

2. Urological & Endocrine disorder:  Varicocele and chronic infection in Urinary   tract. Endocrine dysfunction such as Isolated gonadotropin deficiency, cushing syndrome, hyperprolactinemia, Hemochromatosis, Panhypopituitarism, development and structural defects, Klienfelter syndrome, XX male syndrome, Isolated FSH deficiency, Congenital adrenal hyperplasia, Hyperprolactinemia, estrogen administration, Development and structural defects, Germinal cell aplasia, Cypt-orchidism

3. Nutrition & Vitamin Deficiency : vitamin C, selenium, zinc, and folate

4. Chemotherapy, Obesity, Smoking, Alcohol drinking, Exposure to Heavy metals and other environmental factors.

5. Psychological  : Mental Stress, Anxiety and Depression.

6. Environmental Factor : Recent studies shows contaminated drinking water causes low sperm count and motility.