Causes of Male Infertility

About two-thirds of infertile men have a problem with making sperm in the testes. Either low numbers of sperm are made and/or the sperm that are made do not work properly.

Sperm transport problems are found in about one in every five infertile men, including men who have had a vasectomy, but now wish to have more children. Blockages (obstructions) in the tubes leading sperm away from the testes to the penis can cause a complete lack of sperm in the ejaculated semen.

Other less common causes of infertility include: sexual problems that affect whether semen is able to enter the woman’s vagina for fertilisation to take place (one in 100 infertile couples); low levels of hormones made in the pituitary gland that act on the testes (one in 100 infertile men); and sperm antibodies (found in one in 16 infertile men). In most men sperm antibodies will not affect the chance of a pregnancy but in some men sperm antibodies reduce fertility.

Known causes of male infertility:

Sperm production problems:

• Chromosomal or genetic causes
• Undescended testes (failure of the testes to descend at birth)
• Infections
• Torsion (twisting of the testis in scrotum)
• Varicocele (varicose veins of the testes)
• Medicines and chemicals
• Radiation damage
• Unknown cause

Blockage of sperm transport:

• Infections
• Prostate-related problems
• Absence of vas deferens
• Vasectomy

Sexual problems (erection and ejaculation problems)

• Retrograde and premature ejaculation (find definitions in the ejaculation Concerns section)
• Failure of ejaculation
• Erectile dysfunction
• Infrequent intercourse
• Spinal cord injury
• Prostate surgery
• Damage to nerves
• Some medicines

Hormonal problems

• Pituitary tumours
• Congenital lack of luteinising hormone/follicle stimulating hormone that are important messenger hormones that act on the testes (pituitary problem from birth)
• Anabolic (androgenic) steroid abuse

Sperm antibodies

• Vasectomy
• Injury or infection in the epididymis
• Unknown cause