An investigation of the factors and mechanisms that may determine sex

The present review focuses on the endogenous and exogenous factors that potentially influence the sex ratio in humans. Aims to synthesize all of the different findings gathered from various fields, including reproductive biology, endocrinology, metabolism, immunology and environmental health, in order to improve the comprehension of maternal psychological condition and external stressors interaction and how they determine sex ratio, through the theoretical framework of Trivers – Willard hypothesis (TWH). The reviewed studies were found using databases such as PubMed and Google Scholar, using clear inclusion and exclusion criteria. Thematic categorization followed, separating them into endogenous and exogenous mechanisms. The analysis of the literature is divided into two major domains. The first ones that are mentioned are the endogenous factors and they include maternal glucose, testosterone, cortisol levels without neglecting to mention genetic and immunological mechanisms. Increased glucose seems to favor male offspring whereas its decreased levels are associated with the opposite. Testosterone correlates with male – bias ratios and high cortisol or chronic stress tend to reduce male conceptions. On the other side, the exogenous factors, such as chemical pollutants, natural disasters, nutrition, occupation and psychological stress appear to disrupt hormonal homeostasis, directly influencing sex ratio. In later sections, where the findings get integrated, it’s getting clear that the synergy of internal physiological regulation and external environmental pressures is the key to sex ratio modulation. The findings support the TWH and suggest that maternal condition acts as a mediator between environmental stress and reproductive outcomes. It’s also clear to the sharp reader that the findings support the TWH, meaning that maternal condition is the mediator between environmental stress and reproductive outcomes. Such claim is supported by the literature, which although it’s heterogenous, highlights that joined, both biological and ecological stressors determine sex bias direction. Understanding the interplay between endogenous and exogenous factors not only enhances knowledge of reproductive adaptation but also offers insights into the potential effects of modern ecological changes on fertility and population dynamics.