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Allergies Health Center

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Large Families May Help Keep Allergies Away

But Early Infections Don't Seem to Be Reason for Protection

WebMD Health News

April 29, 2004 -- Having three or more siblings helps prevent allergies, a new study suggests.

In recent years, researchers have been diving deeper into the "hygiene hypothesis," which aims to explain why some people have allergies and some do not. The thought is that being exposed to more dirt and grime may actually decrease the risk of allergies. It suggests that advances in antibiotics and cleaner homes have contributed to increases in allergy, asthma, and eczema by decreasing rates of childhood infection.

Early studies have suggested that having more siblings may decrease the risk of allergies. But in this new study, researchers sought to determine if this is merely an effect of kids being exposed to more infections from other kids.

Danish researchers studied more than 24,000 mother-child pairs to try to get to the bottom of this dirt and allergy association -- specifically, whether exposure to infections early in life decreases the risk of allergies. The children were enrolled in the study when they were 6 to 18 months old.

The researchers were specifically looking at how many of these children developed eczema, a skin condition that causes a red, itchy rash and occurs in kids prone to allergies. In addition to a host of other questions, the moms were asked about the number of infections their kids had before 6 months of age.

The study appears in the current issue of the British Medical Journal.

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