Climate change, evolution, and reproductive health: The impact of water insecurity and heat stress on pregnancy and lactation.

Global water insecurity and rising heat indices have a significant impact on human health. There is an urgent need to understand these climate impacts on the most physiologically and socially vulnerable populations across the globe and use this information to strengthen evidence-based responses. Pregnancy, postpartum, and the first year of life are especially sensitive to water insecurity and extreme heat exposures, as these stages require significantly more access to hydration and cooling resources than other life stages. Extreme heat and water insecurity are ecological stressors forcing parents and alloparents to make difficult decisions between optimal practices for survival and reducing human suffering. Additionally, these stressors may impose physiological trade-offs at the cost of reproductive performance. Here, we examine the changing effects of water insecurity and heat stress throughout pregnancy and lactation using an interdisciplinary, evolutionary, and biocultural lens. We highlight the importance of an evolutionary medicine framework in efforts to investigate the effects of climate change on global health equity. In addition, we outline implications for public health emphasizing the need for targeted policies and healthcare strategies to support pregnant individuals and lactating individuals in affected regions. By integrating evolutionary perspectives with global health concerns, this paper aims to inform future research agendas and policy frameworks aimed at enhancing resilience and adaptation among populations facing escalating climate challenges during critical reproductive phases.