Infertility affects men and women equally. In both men and women, multiple factors can account for difficulty with fertility. Male factors attribute to about 1/3 of infertility problems, while another 1/3 are caused by female factors. The remaining 1/3 of infertile couples have problems caused by a combination of factors in both partners or have unexplained causes. No obvious problem is found in around 10% of couples investigated for infertility. This is when no physical, hormonal or immunological cause for infertility is found in either partner.
More than 90% of male infertility is caused from sperm abnormalities. Sometimes sperm are malformed and improperly shaped, which makes it difficult for the sperm to reach the egg. Abnormal shape and structure can lead to impaired mobility. If sperm cannot move rapidly and accurately towards the egg, fertilization cannot occur.
Some men produce too few sperm. A sperm count of 13.5 million per milliliter of semen or less indicates low sperm concentration. Mild to severely impaired sperm production can be caused by undescended testicles, which occurs when one or both testicles fail to descend from the abdomen into the scrotum during fetal development. This affects sperm production, because the testicles are exposed to higher temperatures. Genetic causes, such as a chromosomal abnormalities can affect fertility, as well. Klinefelter’s syndrome, which is a disorder of the sex chromosomes, causes abnormal development of the testicles, resulting in low or absent sperm production. Cystic fibrosis is a genetic factor that can cause men to have missing or obstructed vas deferens.
There are several reasons and causes for fertility issues in men. A few men produce no sperm at all, though this is rare, affecting less than 5% of infertile men. When no sperm are produced, it is impossible for conception to occur. If this is the case, reproductive organ damage may be to blame. A varicose vein in the scrotum (varicose) could be the cause of infertility, if sperm are being produced but die. Varicose veins can prevent normal cooling of the testicles and prevent sperm from surviving, due to raised testicular temperature.
Problems with the delivery of sperm from the penis into the vagina can keep sperm from getting to the egg, including Retrograde ejaculation. This occurs when semen enters the bladder rather than emerging out through the penis. Also, some men are born with blockage of the ejaculatory ducts (the part of the testicle that contain sperm). Infections may temporarily affect fertility, including sexually transmitted diseases (STDs). These infections can cause scarring and block sperm passage. If mumps (a viral infection) occurs after puberty, inflammation of the testicles can impair sperm production.
A man’s general health and lifestyle may affect fertility. Alcohol, smoking, drugs, emotional stress, vitamin deficiencies, age, heat (hot tubs included) and obesity can all temporarily reduce sperm count and quality. Overexposure to certain environmental elements, including pesticides, lead and toxins reduce sperm count by affecting testicular function or by altering the male hormonal system. Medical conditions such as a severe injury, surgery and certain diseases (including diabetes) can be contributing factors to male infertility.