New research from the US suggests that women who are stressed during pregnancy, for example struggling with financial or relationship issues, are more likely to have babies with immune-related problems such as allergies and asthma.

The research is the work of scientists from Harvard Medical School, Boston, and other colleagues, and was presented at a recent meeting of the American Thoracic Society in Toronto, Canada, on Sunday.

Animal studies have already shown that the immune system of offspring is more sensitive to allergens when mothers are stressed when pregnant.

In this study on human subjects, the researchers said their results suggested the same is probably true of humans: the stress experienced by a pregnant mother may translate into long term health problems for her child.

Co-author Dr Rosalind Wright, of Harvard Medical School said in a prepared statement reported by Reuters that:

“This research adds to a growing body of evidence that links maternal stress such as that precipitated by financial problems or relationship issues to changes in children’s developing immune systems, even during pregnancy.”

According to the Washington Post, Wright, who is also an assistant professor of medicine at Brigham and Women’s Hospital and Harvard Medical School, added that:

“Moms who had elevated levels of stress had children who seemed to be more reactive to allergens, even when exposed to low levels of allergens.”

Dr Junette Peters, a postdoctoral research fellow at Harvard Medical School, said perhaps stress made women more susceptible to allergens by making their “cells more permeable”, and they pass this on to their offspring.

To carry out their study, Wright, Peters and colleagues examined the IgE level of umbilical cord blood taken during the birth of 387 babies in Boston.

IgE stands for immunoglobulin E, an antibody that indicates how sensitive the immune system is to allergens such as dust mites.

The mothers completed surveys about their stress exposure in different areas. Financial pressure, home pressure, safety in the community, problems in relationships, and medical issues, were the most frequently mentioned, said the Washington Post. The dust mite levels in their homes was also assessed.

The researchers found that the mothers who were under the most stress (measured in terms of the number of problem domains reported) while pregnant gave birth to babies with high levels of IgE in their cord blood, even though the level of dust mites in their home environment was low.

This suggested that the stress of the mother was contributing to the higher IgE sensitivity of the baby. This relationship was still significant after the researchers took into account the mother’s class, race, education and smoking history, reported Reuters.

Wright said it was as though stress itself acted like a social pollutant that influenced the body’s immune response.

The results from this study seem to reinforce the findings from Dr Andrea Danese and colleagues at the University of London, who found adults who were treated badly in childhood, for instance they had been rejected by their mothers or sexually abused, had twice the levels of inflammation markers like C-reactive protein and fibrinogen in their blood compared to those that had not. Such inflammatory markers can increase a person’s risk of developing diabetes and heart disease.

Danese presented his research results at a conference in Chicago last week, said Reuters, who reported his comments:

“Stress in childhood may modify developmental trajectories and have a long-term effect on disease risk,” said Danese, who suggested that being mistreated as a child could reduce an adult’s ability to respond to stress by reducing the action of glucocorticoid inflammation inhibitors, which can result in depresson and other mental illnesses.

Sources: Reuters, Washington Post.

Written by: Catharine Paddock, PhD