Researchers from the University of California, Berkeley (UC-B) discovered that children born in Autumn and winter have three times the chances of developing early wheezing, a precursor to asthma, as opposed to those born at other times of the year.
Kim Harley, associate director at UC Berkeley’s Center for Children’s Environmental Health Research and lead author of the new study said “In our study, we took a different tack to understand the link between month of birth and asthma by considering ambient concentrations of fungal spores and pollen, which follow distinct seasonal patterns.”
Kim Harley and colleagues examined 514 children born in 1999 and 2000 in California's Salinas Valley, a region with mild, rainy winters and dry summers. As a part of the study they identified 27 spore and 48 pollen groups. Then over the period of two years the researchers focused on the influence of fungal spore and pollen concentrations at the time of birth, and made an assessment of wheezing from medical records.
Taking into account factors like family history of asthma, air pollution, secondhand smoke, presence of cockroaches, rodents or mould at home, the researchers came to the conclusion that infants who were born in the fall and winter were at a greater risk of developing childhood asthma by age two. The researchers observed, that exposure to pollen concentration during the first three months of birth was linked to early wheezing.
The researchers declared that "Few studies have examined the roles of spore, pollen and particulate matter exposures in the early postnatal period in the development of childhood asthma or chronic wheezing. One strength of this study is that it linked date of birth to specific periods of elevated ambient allergens. Despite the small number of cases, we found several risk factors to be significantly associated with early wheezing."
The researchers added that diagnoses of asthma in children, is generally not made until they start attending school. According to them nearly 40 percent of the children vulnerable to certain allergies and those that reveal early symptoms of wheezing may go on to have childhood asthma.
Dr. Ira Tager, UC Berkeley professor of epidemiology and senior author of the study stated, “We are not in position to say conclusively why some children develop asthma, or to even suggest precautionary measures to help babies born in the fall and winter. We already know that family history is a major risk factor for developing asthma, but the role environmental factors play is still being fleshed out. What this study does is provide valuable clues about airborne allergens that are worth exploring further.”
The results were reported online in Thorax.
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