Women who are stressed in pregnancy may raise the risk of their child developing asthma or other allergies, a study suggests.
Researchers found higher levels of a chemical linked to allergy in the blood of children of stressed mothers. Levels were high even in those who had not been exposed to high levels of dust mites, a recognised allergies trigger.
Harvard Medical School, which studied 387 babies, will present the study to the American Thoracic Society.
It is thought the risk of asthma and allergy is controlled by a complex mix of genetic and environmental factors. However, researchers suspect the impact of these factors may also in some way be influenced by the environment a foetus is exposed to while still in the uterus.
The Harvard team examined the theory that stress during pregnancy can magnify the effect of foetal exposure to substances which can trigger allergy. The researchers measured levels of Immunoglobulin (IgE) - a chemical linked to allergic responses - in the umbilical cord blood of 387 babies.