Researchers say children with eczema and sensitization to allergens by their first birthday were seven times more likely to have food allergies and asthma.

Predicting which children will develop dangerous food allergies and asthma has been a goal for many doctors for decades.

However, often there’s little indication that a child is at risk until they break out into hives or have an asthma attack.

But a new study finds evidence of signs that allergies and asthma can be predicted as early as a child’s first birthday.

A recent study published in the Journal of Allergy and Clinical Immunology found that children who had eczema and an allergen sensitivity by age 1 were seven times more likely to develop asthma and food allergies by age 3 than children who didn’t test positive for these conditions.

The study’s findings could affect how pediatricians and allergists treat children at high risk for developing these conditions.

Canada-based researchers followed more than 2,300 children from their birth through their third birthday to see if they could find clear patterns about the development of food allergies and asthma.

The study was published from researchers working on the ongoing Canada-based CHILD Study.

Those researchers are following more than 3,500 children from birth to understand how exposures in infancy and early childhood affect long-term health.

Doctors call the progression from atopic dermatitis or eczema to asthma and allergies the “atopic march.”

While food allergies, asthma, and eczema may initially seem to be unrelated, they’re all caused by irregularities in the immune system.

As a result, experts have long tried to decipher the relationship between them.

“Over the years, the clinical community has struggled to explain the atopic march,” Dr. Malcolm Sears, founding director of the CHILD Study and a professor of medicine at McMaster University in Ontario, said in a statement.

The researchers found an important distinction for infants with eczema.

While these children were long thought to be at higher risk for allergies and asthma as they got older, there wasn’t a clear indication that they were at higher risk as long as they also didn’t have a sensitization to an allergen.

“These findings help us to understand the interactive effects of AD [atopic dermatitis] and early allergic sensitization on the risk of asthma and food allergy, and show that in combination they pose a significant risk for future allergic disease,” Sears said in a statement.

Understanding who is at risk for developing food allergies or asthma can be crucial to keeping a young child healthy.

An estimated 15 million people have food allergies in the United States, and every year 150 to 200 deaths are caused by these allergic reactions, according to the Centers for Disease Control and Prevention (CDC).

Asthma affects more than 8 percent of children and causes 3,615 deaths in both children and adults every year, according to the CDC.

Dr. Kristie Ross, pediatric pulmonology clinical director at University Hospitals Rainbow Babies and Children’s Hospital in Ohio, said this study could help pediatricians better identify those at high risk for developing dangerous food allergies.

“Once they had that first episode, knowing that the child has a history of atopic dermatitis and is known to be sensitive to allergens,” she told Healthline, “I think we would be more likely to make sure the parent had that medication at home at an ongoing basis.”

She pointed out that many children may have a wheezing episode, but only a small number will go on to develop full-blown asthma.

Only some of the children who are “sensitized” to allergies will develop dangerous food allergies.

Doctors have struggled to figure out which children were at risk and which just had a momentary reaction that didn’t indicate future problems.

Ross said that this study helps clarify some of the risk.

“What’s great about this study is that first of all it’s fairly large study that was done in Canada across several centers, and it was a prospective study so they enrolled children shortly after they were born,” she said.

However, she stressed that there are still limitations to this study and that more research is needed.

Ross pointed out that African-Americans have higher rates of asthma than other demographic groups, but they weren’t highly represented in this study.

“The other thing to be a little bit cautious about with this study… the demographics of the children in the study [are] different than what we would see in U.S. cities,” she said.

Ross also said that the researchers will need to do further testing as the children age, since they will be able to take part in better asthma testing.