Women who are stressed(1) during pregnancy(2) may pass some of that frazzlement(3) to their fetuses(4) in the form of increased sensitivity(5) to allergen(6) exposure(7) and possibly future asthma(8) risk, according to(9) researchers(10) from Harvard Medical School who will present their findings at the American Thoracic(11) Society’s 2008 International Conference in Toronto on Sunday, May 18.

“While predisposition(12) to asthma may be, in part, set at birth(13), the factors that may determine this are not strictly genetic(14). Certain substances(15) in the environment that cause allergies(16), such as dust mites(17), can increase a child’s chance of developing asthma and the effects may begin before birth,” said Rosalind J. Wright, M.D., M.P.H., assistant professor(18) of medicine at Brigham & Women’s Hospital and Harvard Medical School.

Mother’s stress(19) during pregnancy can also influence the babies developing immune system(20). While animal studies suggest that the combination of stress and allergen exposure during pregnancy may magnify(21) the effects on the immune system, this is the first human study to examine this directly. The researchers analyzed levels of maternal(22) stress and mother’s exposure to dust mite allergen in their homes while pregnant(23) with respect to(24) cord blood(25) IgE(26) expression(27)―a marker(28) of the child’s immune response(29) at birth― in 387 infants(30) enrolled(31) in the Asthma Coalition(32) on Community, Environment, and Social Stress(33) (ACCESS) project in Boston.

They found increased levels of IgE expression in cord blood among infants whose mothers experienced higher level stress even when exposed to relatively(34) low levels of dust mite during pregnancy.