Infertility is defined as the failure of a couple to become pregnant after one year of regular, unprotected intercourse. In both men and women the fertility process is complex, and, in many cases, infertility is caused by a combination of problems in both partners that conspire to prevent conception. About 10% to 15% of couples experience some form of infertility, and in approximately 40% of these cases, male infertility is the major factor.
Whether sperm counts are declining overall in industrialized countries is a controversial issue. Although there have been reports of declining male fertility in the US and Europe, several recent studies have not found a drop in sperm counts over the past 50 years. In 2000, a large study based in Los Angeles, for example, found virtually no change in sperm count from a study conducted in the 1950s. Similarly, a Danish study showed no change in sperm quality in men born between 1950 and 1970.
More than 90% of male infertility cases are due to low sperm counts, poor sperm quality, or both. In 60% to 70% of cases of sperm abnormalities, the cause is unknown. It may be the end result of one or a combination of factors that include chronic illness, malnutrition, genetic defects, structural abnormalities, and environmental factors. Partial obstruction anywhere in the long passages through which sperm pass can reduce sperm counts. In one study, obstruction was believed to be a contributing factor in over 60% low sperm count cases. Obstruction itself can be caused by many factors.
What Are The Causes Of Male Infertility?
In general, most cases of male infertility are due to low sperm count. There are usually two reasons for low sperm number…abnormalities in production and obstruction of the tubes that carry sperm.
Most studies show that age is not a common cause of male factor infertility. One study suggested that sperm number and quality do not decline until beyond age 64. One British study has found, however, that as men age, it takes longer for couples to conceive. In the study, the probability of conception taking more than a year doubled from 8% in men under age 25 to 15% in men over 35.
Temporary Causes of Low Sperm Count
Nearly any major physical or mental stress can temporarily reduce sperm count. Some common conditions that lower sperm count temporarily include the following:
Sexual Issues: In less than 1% of males with infertility problems, a problem with sexual intercourse or technique will affect fertility. Impotence, premature ejaculation, dyspareunia (painful intercourse), or psychological or relationship problems can contribute to infertility, although these conditions are usually very treatable. Lubricants used with condoms, including spermicides, oils, Vaseline, can affect fertility. Astroglide or Replens or mineral oil may not be as harmful to sperm.
Testicular Exposure to Overheating: Overheating (such as from high fever, saunas, and hot tubs) may temporarily lower sperm count. Work exposure to overheating may even impair fertility. One French study suggested that driving for only two hours a day can increase temperature in the scrotum and reduce sperm count. This study was small, and more research is needed. A number of studies have found no negative effects on fertility from wearing tight trousers, briefs, or athletic supports, even every day.
Substance Abuse: Cocaine or heavy marijuana use appears to temporarily reduce the number and quality of sperm by as much as 50%. Sperm actually have receptors for certain compounds in marijuana that resemble natural substances and which may impair the sperm’s ability to swim and may also inhibit their ability to penetrate the egg.
Smoking: Smoking impairs sperm motility, reduces sperm lifespan, and may cause genetic changes that affect the offspring. Additionally, a 1999 study found that men who smoke have lower sex drives and less frequent sex.
Specific Genetic Mutations: Genetic defects may contribute to many cases of male infertility. Such mutations may be inherited or caused by environmental assaults.
Inherited Disorders: Inherited disorders can genetically impair fertility. Examples include the following:
- Cystic fibrosis patients often have missing or obstructed vas deferens (the tubes that carry sperm).
- Klinefelters syndrome patients carry two X and one Y chromosomes (the norm is one X and one Y), which causes destruction of the lining of the seminiferous tubules in the testicles during puberty, although most other male physical attributes are unimpaired.
A varicocele is a varicose vein of the testicle (a vein is considered to be varicose when it is abnormally enlarged and twisted). Varicoceles are found in 15% to 20% of all men and in 25% to 40% of infertile men. It is not clear how they affect fertility, or even it does at all. Some theories for their effect include the following:
- Varicocele may partially obstruct the passages through which sperm pass.
- The varicocele may produce higher levels of nitric oxide (a substance that causes blood vessels to dilate). Nitric oxide, in turn, has certain damaging effect that might injure sperm.
- Varicoceles may block oxygen to the sperm.
- Varicocele damages testicles over time.
It should be noted that some evidence supports the idea that varicoceles play a very insignificant role in infertility. One small study suggested that infertility and varicocele may actually have a genetic cause that affects both independently. One eight-year study of men with and without varicoceles found no differences in sperm quality or in the ability to conceive.
Vasectomy and Autoantibodies
Vasectomy, the primary sterility procedure in men, is the most common cause of sperm autoantibodies. Experts believe their typical development is as follows:
- Vasectomy works by severing the vas deferens (the sperm-carrying tube).
- After vasectomy, sperm continue to be produced but instead of being confined to the reproductive passages, they leak out into the body.
- Here, the immune system may perceive them as foreign invaders and develops antibodies to attack them.
Such antibodies often persist, even if a man restores fertility by a successful reversal procedure (vasovasostomy). Even if the surgery successfully restores sperm flow, infertility may persist because of auto-antibodies.
At Coastal Fertility Specialists, male factor infertility is diagnosed by detailed semen analysis that look specifically at the total volume of ejaculate, the number of mobile sperm per milliliter in the ejaculate known as the sperm concentration and sperm motility. We also use the strict criteria developed by Dr. Kruger to determine the percent of the sperm which have a normal shape and normal morphology which is also predictive of the male’s underlying fertility.
Typically we recommend at least 20 million motile sperm per ejaculate for patients to have reasonable pregnancy rates with ovulation induction and intrauterine insemination treatment. Fortunately in-vitro fertilization with intracytoplasmic sperm injection (ICSI) results in extremely high pregnancy rates for those men with lower sperm counts.