Daycare doesn't halt asthma development

September 8, 9:05 AMScience News ExaminerMeg Marquardt

Previous Next

Comment Print Email RSS Subscribe

Subscribe

Get alerts when there is a new article from the Science News Examiner. Read Examiner.com's terms of use.

Email Address   Include other special offers from Examiner.com Terms of Use

 A new Dutch study is a laboratory version of Mythbusters. A team investigated the common 'hygiene hypothesis' that children who attend daycare at a young age are less likely to develop asthma and allergies in later years. They found that daycare had no impact--neither good nor bad--on the development of future conditions.

In a large study that followed 4,000 children, scientists from Erasmus University in the Netherlands tracked the respiratory symptoms of the subjects from birth to eight-years-old. They found that while children who enter daycare may be more prone to illnesses in those early years, that exposure does not confirm protection against later conditions as the 'hygiene hypothesis' states. "We found no evidence for a protective or harmful effect of daycare on the development of asthma symptoms, allergic sensitization, or airway hyper-responsiveness at the age of eight years," wrote Dr. Johan C de Jongste, principle investigator of the study. "Early daycare was associated with more airway symptoms until the age of four years, and only in children without older siblings, with a transient decrease in symptoms between four and eight years." [EurekAlert]

The children were followed via annual parental surveys to ascertain whether the child was in daycare and respiratory status. At the end of the study, over 3,500 patients were also assessed for specific allergies and asthma. The surveys showed that children who enter daycare early (before two years of age) were more likely to wheeze. But by the time those early attendees were five, there seemed to be a shift in that they were 80 percent as likely to wheeze as those who did not attend early. However, these results were not statistically significant--meaning that in reality, there was no real difference between the two groups. Each was just as likely to wheeze. The story was the same for those children who entered daycare after the age of two.

What seemed to have the greatest impact was siblings. "Children with older siblings and early daycare had more than fourfold higher risk of frequent respiratory infections and more than twofold risk of wheezing in the first year compared to children without older siblings and daycare," said Dr. de Jongste. "Importantly, children exposed to both early daycare and older siblings experienced most infections and symptoms in early childhood, without a protective effect on wheeze, inhaled steroid prescription or asthma symptoms." [EurekAlert]

The story boils down to a single conclusion: getting sick at daycare does not prevent or cause asthma or allergies. By the age of eight, all children were equally as likely to develop the conditions. Though the 'hygiene hypothesis' is a widely accepted adage, this study shows very little truth to the belief. The myth appears to be busted. "Early daycare merely seems to shift the burden of respiratory morbidity to an earlier age where it is more troublesome than at a later age," said Dr. de Jongste. "[E]arly daycare should not be promoted for reasons of preventing asthma and allergy." [EurekAlert]