(RxWiki News) As asthma rates have climbed in recent years, researchers have tried to understand all the possible causes of the condition. Now, at least one possible factor can be ruled out.
That factor is low birth weight, according to a recent study. Researchers found no link between low birth weight among children and later development of asthma.
The children included in the study were followed through age 6. There was no major difference between asthma rates among those who were born with a low birth weight compared to those born with a normal birth weight.
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The study, led by Hyeon Yang, MD, of the Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, aimed to understand whether a link existed between low birth weight and asthma.
Low birth weight was defined as 5.5 pounds and lighter.
The researchers included 3,933 children in the study who were born between January 1, 1976 and December 31, 1979 in Rochester, Minnesota. The researchers examined these children's medical records from birth through age 6.
Among the 193 children who were born with a low birth weight, only 6.7 percent (13 total) developed asthma as noted in their medical records.
Among the other 3,740 children born with a normal birth weight, 5.4 percent (201 total) developed asthma.
These two percentages were too close to each other to show that low birth weight might play any part in the development of asthma. The higher percentage among one group is due to chance, based on how few children were born with a low birth weight in the overall study group.
Even when the researchers made adjustments to the analysis to account for other differences between the two groups, the low birth weight group did not show a higher risk for asthma.
The researchers therefore concluded that birth weight does not make a difference in whether someone develops asthma, at least up until age 6.
Researchers continue to try to learn more about possible causes of asthma. One recent link to the condition found by researchers is obesity.
However, background information in this study pointed out that researchers believe asthma arises from a combination of genetic, developmental and environmental factors.
The study was published January 15 in the Annals of Allergy, Asthma and Immunology. The research was funded by the Clinician Scholarly Award from the Mayo Foundation and the Rochester Epidemiology Project from the National Institute on Aging. The authors declared no conflicts of interest.