Levels of stress hormones in expectant mothers during the early stages of pregnancy may significantly affect their offspring’s stress response systems. A comprehensive study conducted on wild Assamese macaques in Thailand has revealed that maternal stress in the early months of pregnancy has a key impact, while higher stress hormone levels later in pregnancy or after birth do not yield the same outcomes. This long-term research, carried out by the University of Göttingen and the German Primate Center — Leibniz Institute for Primate Research, sheds light on how the earliest life stages shape the development of the stress response in natural settings.
Impact of Early Life Stages
The research team examined the relationship between maternal stress and the stress hormone systems of offspring. They discovered that exposure to maternal glucocorticoids during critical developmental phases can significantly activate the hypothalamic-pituitary-adrenal (HPA) axis, which is essential for managing stress. The study identified the first half of pregnancy, particularly during organ development, as a crucial time. “Our findings indicate that the more difficulties a mother faced during early pregnancy—such as food shortages or social strife—the more active the HPA axis of her offspring became,” stated Simone Anzá, a former doctoral researcher at the University of Göttingen and the German Primate Center and the main author of the study.
Field Study Insights
Unlike laboratory-based studies, this research involved observing the monkeys in their natural environments. Over nine years, scientists collected fecal samples from pregnant female macaques to measure glucocorticoid metabolites, which helped determine their exposure to environmental challenges such as food shortages, temperature changes, and social dynamics. These measurements were compared to the stress hormone levels of the young macaques at various life stages. The impact on the offspring’s stress response was evident from infancy through their juvenile years and into adulthood at ages nine to ten. Earlier analyses from this study indicated that early prenatal stress was also linked to changes in growth, gut microbiome composition, and immune function, demonstrating the broad influence of the prenatal environment on various biological systems. In contrast, maternal glucocorticoid levels later in pregnancy or during nursing showed little or different effects.
Importance for Health Research
“Our findings suggest that when mothers experience stress hormones during and shortly after pregnancy significantly impacts the offspring’s development and health. It’s crucial to remember that these effects don’t necessitate severe events; even moderate changes in environmental circumstances can be sufficient,” explained Oliver Schülke, a researcher at the University of Göttingen and the German Primate Center, who led the study. Stress during early pregnancy could also lead to long-term health implications in humans, increasing the risk of stress-related disorders and immune issues. “Our research insights may aid in identifying critical timing and mechanisms for preventive strategies aimed at minimizing long-term health threats,” concluded Oliver Schülke.
