What are the common causes of infertility in men?

Causes of male infertility may include:

1. Abnormal sperm production: or function due to undescended testicles, genetic defects, health problems such as diabetes, or infections such as chlamydia, gonorrhea, mumps or HIV. Enlarged veins in the testes (varicocele) also can affect the quality of sperm.

2. Problems with the delivery of sperm: due to sexual problems, such as premature ejaculation; certain genetic diseases, such as cystic fibrosis; structural problems, such as a blockage in the testicle; or damage or injury to the reproductive organs.

3. Overexposure to certain environmental factors: such as pesticides and other chemicals, and radiation. Cigarette smoking, alcohol, marijuana, anabolic steroids, and taking medications to treat bacterial infections, high blood pressure and depression also can affect fertility. Frequent exposure to heat, such as in saunas or hot tubs, can raise body temperature and may affect sperm production.

4. Damage related to cancer and its treatment: including radiation or chemotherapy. Treatment for cancer can impair sperm production, sometimes severely.