How does age affect male reproductive success?

In assisted reproduction, greater attention has always been paid to the woman’s age in infertile couples, especially due to the decline in oocyte quality. But what happens with male gametes as men age?

In the case of men, there is no abrupt and constant cessation of gamete production, and until recently, it was believed that male age had little impact on reproductive success.

Most studies have shown that aging is associated with changes in semen parameters: a decrease in seminal volume, motility, and altered morphology. Although concentration has not been consistently affected, a decrease in sperm count with significant interindividual variability has been observed. This alteration in semen parameters with age, as mentioned, is neither linear nor constant. Ages of 40, 43, and 45 years have been identified as thresholds for declines in sperm concentration and morphology, motility, and ejaculate volume, respectively. Beyond semen parameters, recent years have highlighted the importance of sperm DNA integrity. In this regard, there is evidence linking aging to sperm DNA damage.

On the other hand, advanced male age has been associated with a higher rate of aneuploidies in embryos derived from donated oocytes.

Lastly, and no less importantly, advanced age has significant ethical implications. In most cases, legislation sets age limits for women to access assisted reproduction techniques. Advanced paternal age can cause anxiety due to potential loss from death or the challenges of caring for an elderly parent. This may lead to early maturity in the child but can also result in issues such as depression, stress, or anxiety. Some authors argue that the loss of a parent at an early age is so devastating that it alone would justify establishing an age limit for assisted reproduction.