Women should avoid being stressed during pregnancy, as recent research warns that stress may raise the risk of their child developing asthma or other allergies.

The findings by researchers from Harvard Medical School were presented Sunday at the American Thoracic Society’s 2008 International Conference in Toronto. They were based on the study of 387 babies enrolled in the Asthma Coalition on Community, Environment and Social project in Boston.

According to the study, mothers who were the most distressed during pregnancy were most likely to give birth to infants with higher levels of Immunoglobulin E or IgE, an immune system chemical linked to allergic responses. For example, a mom having three or more negative events would have a 12 percent increased risk of having a baby with elevated cord blood IgE.

“While predisposition to asthma may be, in part, set at birth, the factors that may determine this are not strictly genetic. This research supports the notion that stress can be thought of as a social pollutant that, when ‘breathed’ into the body, may influence the immune response, similar to the effects of physical pollutants like allergens,” Dr. Rosalind Wright, of Brigham & Women's Hospital and Harvard Medical School, said in a news release, according to Reuters.

However, more study needs to be done to determine the long-term effects of stress during pregnancy.
 
The correlation between stress during pregnancy and babies developing asthma has long been known. Such studies, like the one of Dr. Wright and colleagues, highlight “the need for a healthy and balanced lifestyle during pregnancy, as it could lead to a reduction in asthma and allergies,” said Dr. Mike Thomas, chief medical adviser for the charity Asthma UK, as quoted by BBC News.