NEW DELHI — High maternal stress hormone levels during early pregnancy can have a lasting effect on the health of the children, according to a long-term study on wild monkeys, published on Tuesday.
The study on wild Assamese macaques in Thailand provides important insights into the influence of early life stages on the development of the stress system under natural environmental conditions.
Researchers at the University of Gottingen and the German Primate Center – Leibniz Institute for Primate Research in Germany that the effects of stress were evident till 10 years of age.
The research is relevant as stress in early pregnancy can also have a long-term effect on health in humans and increase the risk of stress disorders and immune problems.
The study found that exposure to stress enhances the hypothalamic-pituitary-adrenal (HPA) axis. The axis plays a central role in coping with stress and can significantly be influenced by exposure to maternal glucocorticoids during development.
The early phase of organ differentiation in the first half of pregnancy proved to be a particularly critical period. “Our research results indicate that the timing of maternal stress hormone exposure during and after pregnancy crucially affects the consequences for the development and health of the offspring.
It is also important to note that these effects do not require catastrophic events, but that even moderate changes in environmental conditions are sufficient,” said Oliver Schulke, a scientist at the University of Gottingen and the German Primate Center.
However, the study published in the journal Proceedings of the Royal Society B showed that elevated stress hormones later during pregnancy or after birth did not have the same effects.
“Our findings may help to identify the timing and mechanisms that preventive measures should address in order to reduce long-term health risks,” Schulke said.
In contrast to studies in the laboratory, the monkeys were observed in their natural habitat. Over nine years, the researchers repeatedly collected faecal samples from pregnant female monkeys and measured the concentration of glucocorticoid metabolites in them to understand the animals' exposure to environmental factors such as food scarcity, temperature fluctuations, and social interactions.
These values were compared with the stress hormone levels of the offspring at different ages. The effects on the stress axis of the offspring were evident from infancy through the juvenile period and into adulthood at nine to 10 years of age.