Oligoasthenoteratozoospermia (OAT) is a condition that includes oligozoospermia (low number of sperm), asthenozoospermia (poor sperm movement), and teratozoospermia (abnormal sperm shape). OAT is the most common cause of male subfertility. Subfertility is when a man cannot get a woman pregnant after 1 year of regular sex without birth control.
The cause may not be known. The following are possible causes of infertility:
Medicines such as steroids and medicines used to treat high blood pressure, cancer, or depression may affect your fertility.
Genetics may cause infertility. This means you may have been born with genes that caused your infertility. Genes may affect sperm production, movement, and transport.
Abnormal hormone levels may affect sperm production.
Antibodies may attack your sperm. Antibodies are proteins made by the immune system that attack viruses or bacteria.
Infections of the male reproductive system, particularly in the prostate, may affect male fertility.
Lifestyle choices such as smoking, drinking alcohol, and using illegal drugs may affect sperm production.
A varicocele is a condition that causes the veins in your scrotum to become enlarged and dilated.