Testosterone is essential for regulating spermatogenesis, sexual function, and systemic physiological processes that influence metabolism, bone density and maintenance, cardiovascular health, psychological health, and cognition. South Korea's fertility crisis, with rates plummeting to 0.65 children per woman in 2023, has brought about many demographic and socioeconomic challenges. 1 While female fertility factors have historically dominated clinical attention, male reproductive health now emerges as equally critical. Meta-analyses have reported an overall 50-60% decrease in sperm count among unselected (i.e., not pre-selected for fertility status) men, predominantly from Western countries, between the early 1970s and the early 2010s and male factors account for roughly half of all infertility cases. 2,3 However, substantial heterogenicity in study populations, laboratory methods, geographic regions and time spans means that such a reduction cannot be generalized globally or confined to a specific age group. 2,4 This decline underscores the need to address male reproductive challenges, including falling sperm counts and the rising prevalence of testosterone deficiency (TD), a common yet frequently overlooked contributor to both infertility and broader health complications. 5
Heng et al. (Sun,) studied this question.