1.6 Common Causes of Male Infertility
A number of factors can contribute to male infertility. These include conditions affecting sperm function, production and delivery, hormonal dysregulation, sexually transmitted diseases, general health and lifestyle factors.
- Age: Though not as marked as in women, a gradual decline in fertility is common after age 35 in men.
- Impaired shape and motility: Abnormal spermatogenesis, or sperm production, may result in sperm that are not able to reach the egg or to penetrate it.
- Low sperm concentration: Normal sperm concentration in men is greater than or equal to 20 million sperm per milliliter of semen. Sperm count lower than 50 percent of this number (10 million) indicates low sperm concentration.
- Varicocele: Varicose veins in the scrotum, called varicocele, may prevent normal cooling of the testicles and lead to reduced sperm count and motility.
- Undescended testicle: This congenital condition occurs when one or both testicles fail to descend from the abdomen into the scrotum during fetal development. When the testicles are exposed to the higher internal body temperature compared to the temperature in the scrotum, sperm production may be affected.
- Testosterone deficiency (male hypogonadism): Disorders of the testicles, or conditions affecting the hypothalamus or pituitary gland in the brain, may result in low testosterone levels that impair fertility.
- Overheating the testicles: Frequent use of saunas or hot tubs can impair sperm production and lower sperm count by raising the core body temperature.
- Genetic defects: Sperm abnormalities may be genetic.
- Sexually transmitted diseases: Repeated bouts of sexually transmitted diseases, such as chlamydia and gonorrhea, can affect sperm motility.
- Sexual issues: Erectile dysfunction, premature ejaculation, painful intercourse and psychological problems can all contribute to infertility.
- Retrograde ejaculation: This occurs when ejaculate does not leave the body during orgasm but rather enters the bladder.
- Blockage of the reproductive system or anatomical irregularities: Blockage of the ejaculatory ducts or various passages through which sperm and ejaculate flow can affect fertility. Men with cystic fibrosis sometimes have a missing or blocked vas deferens, and the lack or misplacement of any part of the reproductive system will often require reconstructive surgery.
- No semen (ejaculate): Men with spinal cord injuries or diseases may not have the ability to produce the fluid required to carry the sperm from the penis into the vagina.
- Anti-sperm antibodies: These antibodies attack sperm and may be present after vasectomy or in the female's body.
- Pesticides and other chemicals: Herbicides and insecticides have been associated with reduced sperm production and testicular cancer. Lead exposure may also cause infertility.
- Malnutrition and weight management: Deficiencies in nutrients such as vitamin C, selenium, zinc and folate may contribute to infertility. Additionally, a high body mass index is associated with impaired fertility in men and women.
- Smoking, alcohol and substance abuse: Use of cocaine or marijuana may temporarily reduce the number and quality of sperm, and smoking tobacco may lower sperm count. Alcohol has also been associated with decreased fertility.
- Cancer treatments: Cancer treatments such as radiation, chemotherapy, and in the case of testicular cancer, the removal of the testicles, can affect fertility.
- Other medical conditions: Fertility may be impaired as a result of various health conditions such as autoimmune disorders, diabetes, thyroid disease, Cushing's syndrome and anemia.
Figure 1.8 Normal and abnormal sperm cells.