Study finds link between birth order and asthma symptoms

“Previous findings of the opposite association between asthma and birth order among older children and adults have served as the basis for what is called the hygiene hypothesis, the idea that exposure to infectious agents at a very young age reduces the risk of asthma in the long term. Only by continuing to follow these children can we determine whether and how birth order predicts diagnosed asthma and asthma that persists throughout childhood,” noted Inge Goldstein, DrPH, a senior lecturer in the Mailman School’s Department of Epidemiology and senior author of the study.

“But even if the patterns of association change as the children grow, we have learned from this study that four year-olds with older siblings are more likely than other four year-olds to experience respiratory symptoms that burden them and their families and impose the costs of care on them and the community,” commented Judith Jacobson, DrPH, associate professor of clinical Epidemiology at the Mailman School and principal investigator of the study, which was funded by the National Heart, Lung, and Blood Institute.

In this study, the prevalence of recent wheeze was higher among boys than girls (32% vs 21%) and higher among children with an asthmatic parent than other children (53% vs 22%). Having younger siblings, unlike having older siblings, was not associated with respiratory symptoms. The associations of birth order with respiratory symptoms were statistically significant only among those children who were not atopic (allergic) and among those without an asthmatic parent.

About the Mailman School of Public Health

The only accredited school of public health in New York City, and among the first in the nation, Columbia University's Mailman School of Public Health provides instruction and research opportunities to more than 1000 graduate students in pursuit of masters and doctoral degrees. Its students and more than 300 multi-disciplinary faculty engage in research and service in the city, nation, and around the world, concentrating on biostatistics, environmental health sciences, epidemiology, health policy and management, population and family health, and sociomedical sciences. www.mailman.columbia.edu