An infection of the uterine cavity during pregnancy combined with premature birth doubles the risk that an African American child will develop asthma

About 8% of pregnancies are marked by such bacterial infections, called chorioamnionitis, but it is not yet clear what proportion of asthma is induced by them. Nor is it clear whether the duration of the infection influences the risk and why different ethnicities respond differently. But blacks have about a 25% higher incidence of asthma and new findings could account for a significant portion of that increase. About 14% of American children suffer from asthma, an inflammation of the airways that is marked by wheezing, shortness of breath, chest tightening and coughing. About half of such cases are believed to be of genetic origin, but the cause of the rest has been a mystery. Researchers found that chorioamnionitis had no apparent effect on the rate of asthma when the fetuses were carried full term. But when the mother suffered from the infection and gave birth prematurely, the risk of asthma developing before the age of 8 was 98% higher in black children, 70% higher in Latino children and 66% higher in whites. No increased risk was observed for children of Asian or Pacific Islander descent.