Gestational exposure to high heat-humidity conditions impairs mouse embryonic development

Unprecedented rates of global warming have created an existential challenge for the sustainable survival of species on this planet. Tropical conditions of high ambient temperature and relative humidity are extremely vulnerable to maternal-child health. Emerging epidemiological studies depict that exposure to extremely hot weather conditions during pregnancy leads to an array of adverse pregnancy outcomes, such as low birth weight, stillbirth, preterm delivery, congenital abnormalities and adult-onset disorders. A lack of understanding of the underlying molecular pathophysiology limits us from developing an effective combat strategy in terms of targeted therapeutics to improvise the combined teratogenic effects of high heat-humidity in pregnancy. To address this, it is important to delineate the effect of hot-humid weather conditions on the process of embryogenesis. However, working with human embryos is technically and ethically challenging. In this study, we have established a mouse model of heat-humidity stress during pregnancy, which essentially recapitulates the adverse pregnancy outcomes observed in humans. Importantly, we have profiled the impact of high heat-humidity exposure during gestation at different stages of embryogenesis using this mouse model. Our results indicate that the teratogenicity of heat-humidity stress gets manifested in a cumulative manner, starting from the pre-implantation stage and becomes severe at the mid-gestation, culminating in significantly higher embryonic deaths and malformations at the late gestational stage of mouse embryogenesis. Overall, our study paves the path for exploring the underlying molecular players that get dysregulated under gestational exposure to hot and humid conditions, resulting in severe embryonic defects.