Determinants of male fertility in the Western Pacific Region: environmental, biological, and lifestyle influences.

Over the past half-century, global fertility rates have declined, with the Western Pacific Region (WPR) experiencing a particularly notable drop. A recent World Health Organisation-commissioned report identified the WPR as exhibiting the highest infertility prevalence at 23.2%, compared to the global average of 17.5%. While the drivers of this decline are complex, one key contributor is male infertility, yet it remains under addressed in research and policy. In this paper, we synthesise current evidence on male infertility with a focus on the WPR. Specifically, we explore environmental, biological, and demographic correlates of male infertility, examine molecular mechanisms regulating sperm function and assess the impact of lifestyle interventions. Our findings highlight significant gaps in regional evidence, advocating for targeted research and culturally tailored interventions to enhance preconception male health within the WPR. Based on this synthesis, we propose preventive strategies and evidence-based recommendations to improve male preconception health in the region.