Born at the Wrong Time? Timing of Infant Birth and the Risk for Childhood Asthma

Tina V. Hartert, MD, MPH


January 05, 2009


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From 1985 to 2001 the prevalence of asthma worldwide has risen 100%. About 300 million people have asthma; over one quarter of a million people die each year from it; and deaths could increase by 20% in the next 10 years.[1] The problem is severe across the world, and developing countries are particularly burdened.[2] Efforts to find effective and targeted primary and secondary asthma prevention measures are needed: Currently, none exist.

One ubiquitous and modifiable environmental factor associated with asthma development is infant respiratory viral infections. However, whether severe infant respiratory viral infections cause asthma or merely serve as a marker for those genetically predisposed to develop asthma was unknown. In a paper in the American Journal of Respiratory and Critical CareMedicine, we addressed this issue by studying over 95,000 infants in our retrospective birth cohort, the Tennessee Asthma Bronchiolitis Study. We determined whether date of birth in relationship to the circulation of epidemic winter respiratory viruses conferred a differential risk of developing early childhood asthma.[3]

When an infant is born does confer a differential risk of developing childhood asthma, and this risk relates to the circulation of winter viruses. Infant age at the winter virus peak following an infant's birth independently predicts asthma development, with the highest risk being birth approximately 4 months prior to the winter virus peak, represented by birth in the fall months in the Northern hemisphere. Birth during this time conferred a nearly 30% increase in odds of developing asthma, and this relationship held true across 5 seasons of study with winter viral peaks shifting by up to 6 weeks in different study years. What's the next critical step in developing asthma prevention strategies? Support for studies designed to determine whether prevention of these ubiquitous infections during infancy prevents asthma.

That's my opinion. I'm Dr. Tina Hartert, Director for the Center for Asthma Research and Associate Professor of Medicine, Vanderbilt University School of Medicine.



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