[8][9] In a random international sample of 11,548 men confirmed to be biological fathers by DNA paternity testing, the oldest father was found to be 66 years old at the birth of his child; the ratio of DNA-confirmed versus DNA-rejected paternity tests around that age is in agreement with the notion of general male infertility above age 65–66.
[13] ASA production are directed against surface antigens on sperm, which can interfere with sperm motility and transport through the female reproductive tract, inhibiting capacitation and acrosome reaction, impaired fertilization, influence on the implantation process, and impaired growth and development of the embryo.
Risk factors for the formation of antisperm antibodies in men include the breakdown of the blood‑testis barrier, trauma and surgery, orchitis, varicocele, infections, prostatitis, testicular cancer, failure of immunosuppression and unprotected receptive anal or oral sex with men.
[18] Klinefelter syndrome is a chromosomal defect that occurs during gamete formation due to a non-disjunction error during cell division.
The reduction of testosterone in the male body normally results in an overall decrease in the production of viable sperm for these individuals thereby forcing them to turn to fertility treatments to father children.
[26] There is increasing evidence that the harmful products of tobacco smoking may damage the testicles[32] and kill sperm,[33][34] but their effect on male fertility is not clear.
[38] The damage manifests by DNA fragmentation and by the increased susceptibility to denaturation upon exposure to heat or acid, the features characteristic of apoptosis of somatic cells.
[40][41] Until recently, scientists have thought that epigenetic markers only affect the individual and are not passed down due to not changing the DNA.
[citation needed] Post-testicular factors decrease male fertility due to conditions that affect the male genital system after testicular sperm production and include defects of the genital tract as well as problems in ejaculation:[citation needed] The diagnosis of infertility begins with a medical history and physical exam by a physician, physician assistant, or nurse practitioner.
[citation needed] The history should include prior testicular or penile insults (torsion, cryptorchidism, trauma), infections (mumps orchitis, epididymitis), environmental factors, excessive heat, radiation, medications, and drug use (anabolic steroids, selective serotonin reuptake inhibitors, alcohol, smoking).
Sexual habits, frequency and timing of intercourse, use of lubricants, and each partner's previous fertility experiences are important.
[citation needed] The past medical or surgical history may reveal thyroid or liver disease (abnormalities of spermatogenesis), diabetic neuropathy (retrograde ejaculation), radical pelvic or retroperitoneal surgery (absent seminal emission secondary to sympathetic nerve injury), or hernia repair (damage to the vas deferens or testicular blood supply).
A blood sample can reveal genetic causes of infertility, e.g. Klinefelter syndrome, a Y chromosome microdeletion, or cystic fibrosis.
[3] Scrotal and transrectal ultrasonography (TRUS) are useful in detecting uni- or bilateral congenital absence of the vas deferens (CBAVD), which may be associated with abnormalities or agenesis of the epididymis, seminal vesicles or kidneys, and indicate the need for testicular sperm extraction.
[3] TRUS plays a key role in assessing azoospermia caused by obstruction, and detecting distal CBAVD or anomalies related to obstruction of the ejaculatory duct, such as abnormalities within the duct itself, a median cyst of the prostate (indicating a need for cyst aspiration), or an impairment of the seminal vesicles to become enlarged or emptied.
[56][55] Giving oral antioxidants to men in couples undergoing in vitro fertilisation for male factor or unexplained subfertility may lead to an increase in the live birth rate but overall the risk of adverse effects is unclear.
[58] Though androgens are absolutely essential for spermatogenesis and therefore male fertility, exogenous testosterone therapy has been found to be ineffective in benefiting men with low sperm count.
[60] This is thought to be because very high local levels of testosterone in the testes (concentrations in the seminiferous tubules are 20- to 100-fold greater than circulating levels)[61] are required to mediate spermatogenesis, and exogenous testosterone therapy (which is administered systemically) cannot achieve these required high local concentrations (at least not without extremely supraphysiological dosages).
[58][60] This is because suppression of gonadotropin levels results in decreased testicular androgen production (causing diminished local concentrations in the testes)[58][60] and because FSH is independently critical for spermatogenesis.
[62][63] In contrast to FSH, LH has little role in male fertility outside of inducing gonadal testosterone production.
[60] As such, clomiphene citrate (an antiestrogen) and aromatase inhibitors such as testolactone or anastrozole have shown effectiveness in benefiting spermatogenesis.
[70][71] Researchers from Montana State University developed precursors of sperm from skin cells of infertile men.
[72][73][74] Sharpe et al. comment on the success of intracytoplasmic sperm injection (ICSI) in women saying, "[t]hus, the woman carries the treatment burden for male infertility, a fairly unique scenario in medical practice.
[79] Various studies in Finland, Southern Tunisia, and Argentina also showed a decline in sperm count, motility, morphology, and seminal volume.
Doctors in India disclosed that the sperm count of a fertile Indian male had decreased by a third over a span of three decades.
The condition and its effects on both men and women is the topic for example of the novel set in Nigeria entitled, The Secret Lives of Baba Segin's Wives.
When stereotypical ideals of manhood are virility and strength, men sharing problems of infertility can face feelings of inadequacy, unworthiness, and have thoughts of suicide.
For the Shona people, since impotence is linked to infertility, an examination to check on the penile function spans from infancy to post marriage.
[83] When the son reaches puberty, they are asked to ejaculate in river banks and for their male elders to examine sperm quality.
[89] The issue attracted media attention after a 2017 meta-analysis found that sperm counts in Western countries had declined by 52.4 percent between 1973 and 2011.