Women tend to blame themselves for their fertility issues, but male factor infertility (when the man’s reproductive system is part of the problem) is the source of approximately 40–50 percent of all infertility cases, according to a review in the Journal of Human Reproductive Sciences.
There are many factors that can contribute to male infertility, such as structural abnormalities of the male reproductive system (including but not limited to the sperm itself), sperm production disorders, ejaculatory disturbances, and immunologic disorders, explains Aaron K. Styer, M.D., reproductive endocrinologist and co-medical director of CCRM Boston. Some causes of infertility in men include:
A varicocele is swelling of one or several of the veins that drain the testicle. Although the exact way that varicoceles cause male infertility is unknown, it may be related to abnormal testicular temperature regulation. Varicoceles may result in reduced sperm quality.
Some infections can interfere with sperm production and sperm health, or cause scarring that blocks the passage of sperm. These include inflammation of the epididymis (epididymitis) or testicles (orchitis) and some sexually transmitted infections, like gonorrhea and chlamydia.
Retrograde ejaculation occurs when semen enters the bladder during orgasm instead of emerging out the tip of the penis. Various health conditions can cause retrograde ejaculation, including diabetes, spinal injuries, medications, and surgery of the bladder, prostate, or urethra.
Antibodies That Attack Sperm
Anti-sperm antibodies are immune system cells that mistakenly identify sperm as harmful invaders and attempt to eliminate them. In men, these anti-sperm antibodies might develop after an infection in the prostate or an injury to the testes that that triggers an immune response.
Cancers and nonmalignant tumors can affect the male reproductive organs directly—through the glands that release hormones related to reproduction, such as the pituitary gland, or through unknown causes—and indirectly, through surgery, radiation, or chemotherapy to treat the tumors.
In some males, during fetal development, one or both testicles fail to descend from the abdomen into the sac that normally contains the testicles (a.k.a. the scrotum). Though the condition is treatable, decreased fertility is still more likely in men who have had this condition.
Abnormality of hormonal systems, including the hypothalamus, pituitary, thyroid, and adrenal glands, can impact sexual function, sperm concentration, and more. Low testosterone (male hypogonadism) and other hormonal problems have a number of possible underlying causes.
Defects of Tubules That Transport Sperm
Many different tubes carry sperm. They can be blocked for a range of reasons, including inadvertent injury from surgery, prior infections, trauma, or abnormal development, such as with cystic fibrosis or similar inherited conditions.
Inherited disorders such as Klinefelter’s syndrome—in which a male is born with two X chromosomes and one Y chromosome (instead of one X and one Y)—cause abnormal development of the male reproductive organs. Other genetic syndromes associated with infertility include cystic fibrosis, Kallmann’s syndrome, and Kartagener’s syndrome.
Problems With Sexual Intercourse
This catch-all diagnosis could refer to trouble keeping or maintaining an erection sufficient for sex (erectile dysfunction), premature ejaculation, painful intercourse, anatomical abnormalities—such as having a urethral opening beneath the penis (hypospadias)—or psychological or relationship troubles that interfere with the ability to get and maintain an erection or ejaculate during sex.
A digestive disorder caused by sensitivity to gluten, celiac disease can cause changes in male hormone production and in sperm morphology and motility.
Testosterone replacement therapy, long-term anabolic steroid use, cancer medications (like chemotherapy), certain anti-fungal medications, and some ulcer drugs, among other medications, can impair sperm production and decrease male fertility.
Certain surgeries may prevent sperm from existing in ejaculation, including vasectomy, inguinal hernia repairs, scrotal or testicular surgeries, prostate surgeries, and large abdominal surgeries performed for testicular and rectal cancers. In most cases, surgery can be performed to either reverse these blockages or to retrieve sperm directly from the epididymis and testicles.
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Editors’ note: We use the terms “woman” and “female” in this article to refer to people with internal reproductive organs; however we understand that not everyone with internal reproductive organs identifies as a woman or a female. We use the terms “man” and “male” to refer to people with external reproductive organs; however we understand that not everyone with external reproductive organs identifies as a man or a male.