Infertility in men is defined as the inability to reproduce after 1 year of unprotected intercourse, assuming the female partner is perfectly healthy. Infertility affects approximately 10-15% of couples belonging to the reproductive age group. Though the worldwide prevalence of infertility has been stable over the past 50 years, there has been a shift in the cause of infertility in men and women .
Whether advanced age can be a cause of infertility in men is a concern for many. Although conception may take a little longer with older men, fertility rates have found to be similar to those in younger men.
For the purpose of ease of understanding let us describe the various causes of infertility in men under different categories .The causes of infertility in men can be categorized as :
PreTesticular Causes (of infertility in men):
The PreTesticular causes may be hormonal imbalances, dysfunction of the hypothalamo-pituitary-gonadal axis, or problems relating to other systems of the body which may have an effect on male fertility. The various PreTesticular causes of infertility in men are:
Idiopathic hypogonadotrophic hypogonadism
Failure to release Gonadotrophin releasing hormone from the hypothalamus without any underlying cause leads to decreased trigger to the pituitary gland to release hormones such as follicle stimulating hormones and luteinizing hormone which in turn causes lowered levels of stimulation to the testes to produce sperms and testosterone.
Prolactin secreting pituitary tumour
A prolactin secreting tumour called prolactinoma is the most common pituitary tumour. High levels of prolactin hormone secreted by the tumour may inhibit the secretion of Gonadrotrophin releasing hormone from the hypothalamus, thereby leading to decreased secretion of follicle stimulating hormone and luteinizing hormone .This will in turn lead to decreased levels of testosterone causing sexual dysfunction or infertility in some men.
Luteinising hormone deficiency
The levels of luteinizing hormone secretion may be low for no specific reason. Follicle stimulating hormone levels may be normal. The above hormonal imbalances may result in low ejaculatory volume.
Follicle stimulating hormone deficiency
Isolated deficiency of follicle stimulating hormone is very rare. Patients with low levels of follicle stimulating hormone may have oligospermia or decreased number of sperms in the semen. The levels of luteinizing hormone will be normal.
Persons with thalassemia undergo multiple blood transfusions so as to correct anemia. As a result of multiple blood transfusions they will have iron overload which ultimately get deposited in various organs including the pituitary gland and the testes. The deposition of iron will lead to damage to pituitary gland and testes resulting in their inefficiency.
In Cushing disease there is increased production of cortisol from the adrenal gland which inhibits Gonadotrophin releasing hormone secretion from the hypothalamus. This ultimately leads to decreased hormonal stimulation of the testes to produce sperms and the male sex hormone testosterone.
There will be elevated estrogen levels in circulation in liver failure, severe obesity etc. Estrogen inhibits the secretion of follicle stimulating hormone and luteinizing hormone from the pituitary gland. This results in decreased testosterone levels and lowered sperm production.
Testicular causes of infertility in men :
Androgen Receptor Dysfunction
In some men the receptors for male sex hormones may be defective leading to reduced response of the testicles to the testosterone produced. This leads to decreased production of sperms in response to stimulation.
Bilateral anorchia refers bilaterally absent testes. The male is born without both the testes, the potential causes of which are still unknown. The men remain infertile despite administration of hormones.
A varicocele is the dilatation of the veins of the scrotum. It is present in about 15 % of the men. The exact cause for developing varicocele is not known. It may cause infertility due to impaired sperm production. The impaired sperm production may be attributed to pressure effects on the testes, elevated scrotal temperatures and inadequate oxygenation of the testes.
Cryptorchidism refers to undescended testes caused by failure of the testes to descend down into the scrotal sac from its abdominal location. About 3 % of full term male babies are born with an undescended testes but fewer than 1% remain to be undescended by the age of 1 year. It may be undescended unilaterally or bilaterally. Males with undescended testes have increased risk of infertility. The farther from the scrotum and longer the duration the testes resides outside the scrotum, the greater the likelihood of infertility.
The testes are at increased risk for physical and thermal trauma due their exposed position. Testicular trauma if severe enough is associated with the risk of infertility in some men.
Anticancer chemotherapy drugs are toxic to actively dividing cells. In the testicles ,cells giving rise to sperms are in a stage of active cell division. Hence the cells of the testes giving rise to sperms are adversely affected by chemotherapy drugs. This may result in infertility in men. Learn about Cryopreservation before undergoing Chemotherapy.
The Sertoli cells and stem cells in the testes are highly sensitive to radiations. Radiation therapy may sometimes lead to infertility and if in case sperms are produced, they may have chromosomal abnormalities. Even if the testes are shielded during radiotherapy below the diaphragm, infertility may occur due to toxicity to the testes caused by reactive oxygen free radicals released.
Orchitis is the inflammation of the testis. It develops in adults who are infected with mumps virus. The testes may be unilaterally affected or bilaterally affected. About 25% of men develop inflammation of the testes following mumps attack. The inflammation in the testes may lead to infertility due to intense swelling and compression. Sometimes the testes may become atrophic after recovery from the inflammation.
Post Testicular Causes for Infertility in Men
Post testicular causes of infertility in men include problems with transportation of sperm through the ductal system of the testes.
Congenital blockage of ductal system
The testicular ductal system may be congenitally blocked. Male children born to mothers who were exposed to the drug diethylstilbesterol (an estrogen) during pregnancy. Vas deferens may be blocked at two or more sites in the condition called segmental dysplasia.
Acquired blockage of ductal system
Certain infections such as Chlamydia, gonorrhea, tuberculosis may cause the epididymis to get blocked. The blockage secondary to infections happens due to adhesions and scarring within the ductal system. Trauma, previous attempts at sperm aspiration and inguinal surgeries also may result in scarring and blockage of the ducts.
Defects in Cilia
Immotile cilia syndrome may cause men to have defective motility of the sperms associated with defective function of ciliary processes of the respiratory tract. Men with immotile cilia may experience recurrent attacks of sinusitis, bronchiectasis and respiratory infections due to inadequate ciliary movement and clearance of mucus within the respiratory tract. Sperms which are immotile fail to reach the fallopian tube in the female so as to fertilise the ovum.
Ejaculatory Duct Obstruction
An obstruction within the ejaculatory duct may result in male infertility. The obstruction may be caused by stones within the ejaculatory duct or externally by prostatic cysts. In case of ejaculatory duct obstruction men may have decreased volume of ejaculate, experience painful ejaculation or have blood tinged ejaculate.
Ejaculation Issues / Problems
Ejaculation issues may be in the form of anejaculation or retrograde ejaculation. Anejaculation is the failure to ejaculate during an orgasm. Retrograde ejaculation refers to reflux of the ejaculate or entry of the ejaculate into the bladder instead of passing outside through the urethra. Anejaculation may occur due to lack of rhythmic contractions during ejaculation. It may happen in various conditions such as:
- Diabetic Neuropathy
- Spinal Cord Injury
- Multiple Sclerosis
- Certain Medicines / Medication
Retrograde ejaculation may occur due to an open bladder neck. Retrograde ejaculation is seen after:
- Bladder Neck Surgery
- Retroperitoneal Lymph node Dissection and Removal
- Colon or Rectal Surgery
Apart from the above detailed causes of infertility in men , many lifestyle factors and environmental factors are known to have effects on male fertility.
LifeStyle Factors affecting Fertility in Men:
Many things in the present day lifestyle have been shown to have adverse effects on Male Fertility. The various lifestyle causes of Infertility in Men are as follows:
Smoking has been shown to be associated with decrease in sperm count and motility. It has also been found to be associated with altered sperm morphology. Smoking may result in Male Infertility by all the above mentioned mechanisms.
Using Marijuana affects Male Infertility by decreasing sperm count and the quality of sperms. The metabolites of Marijuana are toxic to sperms.
Alcohol use interferes with the synthesis of male sex hormone, testosterone and has an effect on sperm count. Alcohol may reduce sexual response and lead to impotence.
Excessive Exercise / Stress
Exercise should be encouraged on a daily basis in moderation. But excessive and compulsive exercising has been found to be associated with decreased sperm count in men. Strenuous exercising may also add to stress levels.
Extreme Weight loss or Weight gain
Extremes of weight have an impact on Fertility (and overall health). Obesity in men has been found to be associated with poor sperm quality. Inadequate diet leading to weight loss also may have adverse effects on Male Infertility.
Environmental Causes for Infertility in Men
Exposure to lead and other heavy metals, pesticides etc. has been found to be associated with Male Infertility. Other factors such as excessive heat exposure, Microwave radiation and Ultrasonography are controversial as infertility inducing factors.
An environmental Pollutant bisphenol A (BPA) also has been shown to have deleterious effects on Male Infertility.