Washington, March 21 (IANS): As a first born, you are more likely to suffer from particular allergies than your younger siblings, a new research says.
"It has been established that individuals with increased birth order have a smaller risk of allergy," said Takashi Kusunoki, a paediatrician at the Shiga Medical Centre for Children and Kyoto University, Japan, who led the study.
"However, the significance of the effect may differ by allergic diseases," he said.
Kusunoki and his colleagues looked at the significance of the birth order effect on the prevalence of asthma, atopic dermatitis, allergic rhinitis, allergic conjunctivitis and food allergy, says a statement of the American Academy of Allergy, Asthma & Immunology.
Parents of more than 13,000 children between the ages of seven and 15 were surveyed. Results showed there was no significant difference in the prevalence of asthma or atopic dermatitis according to birth order.
However, the prevalence of rhinitis, conjunctivitis and food allergy decreased significantly as birth order increased.
For example, the prevalence of food allergy was four percent in first born children, 3.5 percent in second born and 2.6 percent for children born later.
The same effect was also observed when looking specifically at the presence of food allergy in the children during infancy.
The incidence of food allergy decreased significantly as birth order increased, leading the researchers to suggest that this birth order effect may have a prenatal origin.