Firstborn Children At Greater Risk of Certain Allergies, Study Says
Japanese researchers surveyed parents of more than 13,000 children aged 7 to 15 and found that overall, firstborn children were more likely to have hay fever, pink eye due to allergy, and food allergies.
The prevalence of food allergies in firstborn children was 4 percent, 3.5 percent in second-born children, and 2.6 percent in later-born children.
“It has been established that individuals with increased birth order have a smaller risk of allergy. However, the significance of the effect may differ by allergic diseases,” said first author of the study, Dr. Takashi Kusunoki, of the pediatrics department at Shiga Medical Center for Children and Kyoto University, both in Japan.
However, in the same study, the researchers found that a child’s birth order did not seem to affect the prevalence of asthma or eczema.
Further research is needed to learn more about how birth order affects allergy risk, researchers said.