There are 6.3 million children with asthma in the United States. Unfortunately, even though it is one of the leading reasons for school absenteeism across the country, we still don’t know exactly what causes asthma, or how to cure it. While genetics evidently play some role in the development of asthma, researchers continue to work to determine other factors that might contribute to -- or perhaps even serve as a root cause of -- the condition.
A few of the recent theories on what may contribute to the development of asthma include:
The hygiene hypothesis
According to the American Academy of Allergy, Asthma and Immunology, the hygiene hypothesis suggests that our overly clean environment may be contributing to the ever-increasing rates of asthma and allergic conditions. The theory poses that because infants and children today are, generally speaking, exposed to fewer germs than kids of previous generations were, their immune systems are not being properly trained to distinguish between harmless and harmful irritants. These children end up with immune systems that overreact to otherwise harmless triggers like pollen or food proteins. Those subsequent reactions manifest as food allergies, asthma, eczema, and other allergic conditions.
RSV infection in infancy
In 2015 the Inflammatory Mechanisms Section of the Laboratory of Immunobiochemistry at the CDC studied the role of early respiratory syncytial virus, or RSV, in the development of childhood asthma. What they found was that the way an infant’s immature immune system responds to RSV may inadvertently trigger asthma. The researchers theorized that the dynamics outlined in the hygiene hypothesis play a role in the immune systems of infants with RSV not responding appropriately, i.e., triggering asthma in some of these children. More research is needed to prove causation between these events.
Exposure to acetaminophen during pregnancy
Acetaminophen is one of the most commonly used pain-relief and fever-reducing medications in the United States. Many pregnant women use acetaminophen because it has long been thought to be safer than the alternatives (aspirin or ibuprofen). But a study published in 2016 by the International Journal of Epidemiology showed a correlation between the development of asthma in children by the age of 3 when the mother used acetaminophen during pregnancy. This was especially true when the mother used the medication to treat more than one ailment. While correlation is not causation, it is definitely worth discussing with your OB/GYN if you are pregnant and in need of a pain reliever.
Exposure to sunlight during pregnancy
Another theory as to why children develop asthma has to do with how much or how little sunlight the mother is exposed to during the second trimester of pregnancy. Ultraviolet rays from sunlight trigger vitamin D synthesis in humans, and a study of 260,000 Americans conducted in 2016 by Harvard University found that doubling the amount of second trimester sunshine correlated to a 10 percent reduction in children's development of asthma. If you live in an area of the country that does not get a great deal of sunshine, or if you are in your second trimester of pregnancy during the winter months, you might want to discuss vitamin D supplementation or the use of sun lamp therapy with your OB/GYN.
While there are still no clear-cut answers as to why some children develop asthma and others don’t, these new areas of research look promising. Parents with asthma or a family history of asthma may want to continue this discussion with both their OB/GYN and/or their children’s pediatrician.
Jennifer has a bachelor's degree in dietetics as well as graduate work in public health and nutrition.She has worked with families dealing with digestive disease, asthma and food allergies for the past 12 years.Jennifer also serves the Board of Directors for Pediatric Adolescent Gastroesophageal Reflux Association (PAGER).