Why are Autumn babies more likely to have allergies?

A new study says babies born Sept-Oct have higher risk of allergic diseases. But why?

Food allergies are on the rise, with more than five million children, about two kids in every school classroom, now suffering from allergy to at least one food, according to a new study published in the Journal of Allergy and Clinical Immunology: In Practice.

The study suggests that the time of year that a baby is born may be a risk factor for food allergies, say researchers, adding that babies born in the Autumn season, lasting from September to November, are at higher risk of allergic diseases.

What causes allergies in children?

The research team determined that many allergic conditions likely start with dry, cracked skin, which leads to a chain reaction of allergic diseases known as the 'atopic march'.

It begins in infancy with eczema and leads to food allergies, asthma and hay fever later in childhood.

“When food particles are absorbed through [weakened] skin [as is the case with eczema], rather than being digested, the body sees them as foreign and creates antibodies against them,” said Jessica Hui, MD, a pediatrician at National Jewish Health and lead author of the study.

“Then when a child eats this food, those antibodies recognize the food and trigger allergic reactions such as hives, vomiting or even anaphylaxis.”

Why are Autumn babies at higher risk?

“We looked at every child treated in our clinic, and those born in the fall were much more likely to experience all of the conditions associated with the atopic march,” said Hui. “Now we are learning more about why that is and we strongly believe it stems from the bacteria on the skin and how they affect the skin barrier.”

It seems that Autumn births are more closely associated with colonization of a harmful bacteria called Staphylococcus aureus, which can weaken the skin barrier. This causes the dry, itchy, painful skin associated with eczema and allows different bacteria, food particles and pathogens to penetrate the skin and enter the body.

Researchers are now conducting a clinical trial to look at a wide variety of factors that may contribute to this weakened skin barrier in babies.

They're enrolling pregnant women and following their babies into early childhood to consider everything from environmental factors to genetics to medications taken and products used in the home.

They hope that this will not only help explain why babies born in the Autumn are at greater risk, but will also help develop solutions to stop the atopic march in its tracks.

"We think if we can intervene at a very young age, even right after the baby's out of the womb, then potentially that's a way for us to try to stop the development of this atopic march," Hui said.

Other potential solutions to prevent the atopic march is sealing the skin barriers of babies with eczema using wet wraps and lotions and introducing allergenic food early in life for kids at risk, the authors noted.