Sperm counts have been declining, and there are several factors that contribute to this phenomenon. The following data provide some insight into the causes of declining sperm counts, including: - Aging: As men age, their sperm concentrations remain unchanged, but they exhibit lower ejaculated volume, decreased sperm motility, and a higher percentage of abnormal spermatozoa. However, these parameters remain within normal limits in most of the older subjects. Serum levels of inhibin B decrease with aging, which is secreted by Sertoli cells and mediates feedback inhibition of pituitary FSH secretion. - Lifestyle factors: Several lifestyle factors can affect sperm quality and quantity. For instance, tobacco smoking has been associated with decreased sperm quantity and quality and possibly fertility. In utero exposure to smoking may have a detrimental effect on sperm production in adulthood. Occupational and environmental exposure has also been associated with lower-quality semen analyses. Consumption of fruits and vegetables with high pesticide residues might also be associated with lower semen quality. - Obesity: Being underweight or overweight can affect semen parameters. An observational study reported that being underweight was associated with lower sperm concentration, total sperm number, and total motile sperm count while being overweight was associated with lower semen volume, total sperm number, and total motile sperm count. - Genetic factors: Approximately 20 percent of men with suboptimal semen parameters have microdeletions of the long arm of the Y chromosome in a region thought to play a critical role in spermatogenesis. Genetic evaluation (karyotype and Y chromosome microdeletion) is recommended for those with abnormal sperm parameters based on WHO criteria. - Medical conditions: Chronic illnesses such as diabetes mellitus, vascular or neuropathic disease of the penis, medications, depression can cause reduced sexual activity and sexual dysfunction leading to male infertility. It is important to note that infertility is not always due to male factors alone; approximately 40 percent of infertility cases are thought to be due to male factors, 40 percent to female factors, and 20 percent to both. When a couple is infertile, the man and woman usually are evaluated together. The evaluation for infertility in men usually begins with a semen analysis, also known as a sperm count. If the semen analysis is completely normal, further evaluation rarely is needed. If the first semen analysis is not normal, one or more additional samples may be collected. If more than one of the samples is abnormal, a more complete evaluation should be done. This evaluation typically includes a complete medical history, including sexual and general development, previous illnesses, medications and exposures. In conclusion, declining sperm counts can be attributed to several factors such as aging, lifestyle factors like smoking and obesity, genetic factors like microdeletions of the long arm of the Y chromosome in a region thought to play a critical role in spermatogenesis and medical conditions like chronic illnesses such as diabetes mellitus or depression that cause reduced sexual activity leading to male infertility. Analyzing DNA fragmentation
such that fragmentation below 25 per cent can be considered optimal; above this, the chance of spontaneous conception decreases. Beyond 50 per cent, the success rate of IVF is also lower.
