Kids with eczema may develop more allergies by the time they reach age three, a new study has found.

The researchers, who evaluated the clinical and epidemiologic patterns of pediatric allergy, found that kids with allergies follow a predictable pattern of developing more allergies, known as an "allergic march."

"If a child is diagnosed with one form of allergy, their likelihood of developing a second form is much higher than the general population," said Dr. David Hill, a study author from the University of Pennsylvania. The findings of the study were published in the journal Pediatrics.

The team evaluated data from more than 200,000 children, collected between 1999 and 2020. They found that the allergies tend to begin at an average age of 4 months, with the diagnosis of eczema or atopic dermatitis. By around 13 months, the kids develop food allergies and asthma, followed by allergic rhinitis, or hay fever by around 26 months. In some rare cases, children develop a chronic immune system disease called eosinophilic esophagitis by 35 months.

Around 10% of the study population had eczema and 19.7% of them developed hay fever.

"This is the first national study done with patient health care data to show that the allergic march is occurring on a national level," Hill said.

However, the allergic march does not mean that every child who develops eczema will eventually develop all kinds of allergies. The findings suggest that 20% of children had at least one type of allergy and over 13% had at least two types of allergic conditions.

"Each child is different. Some may have one, others may have a couple, others may have all of them," Dr. Stanislaw Gabryszewski, who led the study, said.

Researchers hope the study would be helpful for parents and physicians to keep a close watch on kids who develop eczema. Timely treatment of the condition could halt the progression of other allergies in the future.

"Eczema early in life is the No. 1 risk factor for developing allergies later in life, far more than family history," Dr. Ruchi Gupta, founding director of the Center for Food Allergy and Asthma Research at Northwestern University, told NBC News. Gupta was not involved in the study.