18. Causes and lifestyle factors of male infertility

Infertility and contraception

The concept of male infertility

If a married couple has lived together for more than two years without using contraception and has failed to conceive, and the cause is attributed to the male partner, this condition is called male infertility.

With the development of science, infertility has become an independent specialty. Some countries have even established infertility societies and published infertility journals, thus gradually clarifying the concepts of infertility and sterility. Strictly speaking, infertility refers to the inability to conceive after a prolonged period of unprotected intercourse; sterility, on the other hand, refers to the inability to deliver a live baby due to miscarriage, premature birth, or stillbirth, even though the woman is able to conceive. In short, infertility involves fertilization disorders, meaning the sperm and egg cannot combine normally, while sterility involves the ability of sperm and egg to combine, but after implantation, the embryo or fetus develops abnormally. These are two different environmental obstacles. Therefore, strictly speaking, male infertility would be more appropriate, but for the sake of reader convenience, it will still be referred to as male sterility.

Regarding the time frame for determining infertility, some countries set it at one year after marriage, while others base it on the highest miscarriage-to-pregnancy rate in the second year after marriage, setting it at two years. my country sets it at three years, and some other countries set it at five years. Currently, the International Organization of Gynecology and Obstetrics has set its time frame at two years.

In ancient China, the blame for infertility was often placed on women. Therefore, there was much discussion about female infertility, and many remedies were available. However, research on male infertility was relatively insufficient. In fact, male infertility is not uncommon and deserves sufficient attention.

What percentage of men are infertile? The proportion of male infertility is related to racial and ethnic lifestyles, customs, and social, climatic, and environmental factors. According to reports, there are approximately 150 million male infertile individuals worldwide, with about 35 million in my country. Infertile couples account for about 10% of couples of reproductive age. In some industrialized and densely populated cities abroad, the rate is as high as 15%, and in some European and American countries, it is even as high as 30%. An analysis of 665 infertile couples examined over 15 years revealed that in 28% of cases, infertility was solely due to male factors; in 7.5%, both partners had low fertility; and in 17.6%, the cause was unknown.

Since male infertility accounts for a significant proportion of cases, we need to investigate and find the causes. Proactive prevention and early treatment are key to reducing the proportion of male infertility.

Causes of male infertility

Physiological reasons

1. Sexual dysfunction

① Erectile dysfunction, also known as impotence, is the inability to achieve or maintain an erection sufficient for satisfactory sexual intercourse, thus preventing conception. This condition is relatively common, and those affected often experience varying degrees of marital discord, disharmony in their family life, anxiety, and stress.

② Premature ejaculation occurs when a man ejaculates before intercourse, preventing conception because the sperm cannot enter the vagina. This often occurs in men who have masturbated before marriage and have developed neurasthenia.

③ Although patients with ejaculatory dysfunction have no abnormalities in their external genitalia, accessory glands, or libido and can have sexual intercourse, they often experience mental stress and psychological burdens, such as disharmony in their marital relationship or an eagerness to have children, which prevents the ejaculation of semen during intercourse and thus prevents them from conceiving.

④ Retrograde ejaculation: Some people cannot conceive because of uncoordinated ejaculation center function, bladder sphincter failure, and inability of the internal urethral orifice to close effectively. Therefore, after orgasm, semen does not ejaculate from the urethral orifice but flows back into the bladder.

2. Semen abnormalities

Normal semen is a white or grayish-white opaque liquid, averaging 3-5 ml per ejaculation, and liquefies spontaneously within about 30 minutes after ejaculation. Of the ejaculated sperm, more than 60% should be motile, and no more than 20% should be abnormal. Semen that does not meet these standards is considered abnormal.

① Azoospermia is defined as the absence of sperm in multiple semen analyses. Clinically, it is further divided into true azoospermia and false azoospermia. The former refers to the inability of the testes to produce sperm, while the latter refers to the normal development of the testes, which can produce sperm, but cannot ejaculate sperm due to obstruction of the vas deferens, inflammation of the reproductive system, or damage. This latter condition is curable.

② Low sperm count in semen analysis, with a sperm count below 0.6 billion per milliliter, reduces the chances of conception.

③ Semen does not liquefy: If semen does not liquefy within half an hour after ejaculation, it restricts the sperm's motility. The longer the semen stays in the vagina, the higher the sperm mortality rate, making conception difficult.

④ Too many dead sperm, too many abnormal sperm, and insufficient sperm motility affect conception.

⑤ Insufficient semen volume is not enough to dilute the acidic secretions in the vagina, thus affecting fertility.

3. Congenital or acquired organic lesions of the reproductive organs

Organic lesions of the reproductive organs, such as congenital absence of testes, testicular hypoplasia, cryptorchidism, intersex conditions, vas deferens obstruction, and hypospadias, cannot prevent a woman from conceiving.

4. Immunological infertility

Among couples with unexplained infertility, a significant proportion suffer from immunological infertility. This refers to the fact that sperm is an autoantigen, which can induce the body to produce antisperm antibodies. These antibodies inhibit sperm motility, affecting the sperm's passage through the female reproductive tract to meet the egg and interfering with fertilization.

Life reasons

1. Nutritional factors

A man's fertility is related to many factors, among which nutrition is closely linked. This understanding was recognized by the ancient Chinese, as stated in the Mencius, "Food and sex are human nature" (Mencius, Gaozi I). Numerous studies have also confirmed the relationship between nutritional status and male fertility. Certain nutrients are essential for male reproductive physiology; a deficiency in these substances can hinder the normal development of the gonads and sperm production, and in severe cases, can lead to azoospermia and infertility.

First, adequate protein and vitamins can promote spermatogenesis; vitamins A, B, and E can all enhance spermatogenesis. It is generally believed that vitamin A deficiency can weaken spermatogenesis, while vitamin E deficiency may lead to testicular damage.

In addition, certain trace elements in the human body can also have a significant impact on male fertility; a deficiency in these elements can also lead to male infertility. Studies have shown that elements such as zinc, manganese, and selenium are essential for maintaining normal male fertility. Zinc, in particular, participates in multiple aspects of male reproductive physiology, such as the synthesis and transport of testicular enzymes, sperm motility, and fertilization. Zinc deficiency can lead to hypogonadism in men: smaller and softer testes, and reduced or absent sperm production. Manganese deficiency can cause sperm maturation disorders, leading to oligospermia or azoospermia. Selenium deficiency can reduce the energy source required for sperm motility, thus decreasing sperm motility.

Many foreign experts have also conducted extensive research using modern science and technology on the nutritional effects of certain foods on male fertility. They believe that foods that definitely enhance sperm production include: yam, eel, ginkgo, and sea cucumber, because they contain a relatively high amount of arginine, an essential component for sperm formation. Foods rich in arginine include frozen tofu, tofu skin, peanuts, walnuts, and sesame seeds.

Foods that can enhance libido and fertility include jujubes, sesame seeds, honey, grapes, lotus seeds, yams, walnuts, fungi, dog meat, mutton, and animal penises.

It should be noted that although nutrition is closely related to male fertility, and deficiencies may lead to decreased male sexual reproductive ability, excessive supplementation of these nutrients should be avoided. Otherwise, new side effects may occur, causing even more serious damage to male reproductive ability. This is also a case of the principle that too much of a good thing can be bad.

2. Temperature factor

High temperatures can affect the scrotum and lead to impaired sperm development. This is most commonly seen in men who frequently take hot baths or saunas, often resulting in decreased fertility. Therefore, some people use warm testicles for contraception. Furthermore, men who wear tight pants for extended periods are also more prone to infertility, as tight pants raise testicular temperature or obstruct blood flow to the scrotum, reducing sperm production.

Although experiments have shown that cold stimulation can increase sperm count, excessive cold stimulation can also lead to a decline in sperm quality and separation of the sperm head and tail, which undoubtedly harms fertility.

3. Age factor

From a physiological perspective, fertility is closely related to the development, maturation, and aging of the reproductive system. Generally speaking, a man's fertility begins to decline gradually from the age of 35, and this decline intensifies with age, reaching a significant level after the age of 70, and eventually ceasing altogether.

4. Exercise factors

Exercise can promote health and longevity, but strenuous and excessive exercise often puts the body in a state of stress and severely disrupts the endocrine system in the short term through several mechanisms. Ultimately, this leads to the sustained suppression of hypothalamic gonadotropin-releasing hormone, thereby affecting fertility directly or indirectly.

It is worth mentioning that long-term cycling may also cause infertility, because the bicycle seat compresses the scrotum, urethra, and prostate for a long time, which can easily cause congestion and affect fertility.

5. Alcohol abuse, smoking, and drug use

Long-term alcohol abuse can affect sperm development, especially in people with chronic alcoholism, where 70% show poor sperm development or reduced sperm motility, and even if conception occurs, there is a risk of birth defects.

Smoking is also a cause of infertility, as nicotine in cigarettes can lower sex hormone levels and kill sperm. Some reports indicate that men who smoke 20 cigarettes a day have a sperm survival rate of only about 49%.

Long-term marijuana use can suppress sperm production. In addition, natural opioids can also reduce fertility, and heroin and methaqualone can also lead to sexual dysfunction.

6. Psychological factors

Clinically, many male infertility patients have or have some mental or psychological issues. Prolonged depression, frustration, tension, and fear are all detrimental to fertility. Studies have shown that depression affects not only neuroendocrine function but also testicular spermatogenesis and sexual function. Those in a state of chronic stress experience disruptions in neurotransmission and gonadotropin release due to the presence of biogenic amines, which can inhibit testosterone production and thus affect sperm production.

Therefore, men who want to have children must relax and maintain an optimistic and healthy mindset, which is very beneficial for fertility and healthy offspring.