Related Experiment Video
Updated: Feb 15, 2026
A Novel Method for Involving Women of Color at High Risk for Preterm Birth in Research Priority Setting
Published on: January 12, 2018
Birth order and paediatric allergic disease: A nationwide longitudinal survey
T Kikkawa1,2, T Yorifuji3, Y Fujii4
1Department of Pediatrics, Okayama University Hospital, Okayama, Japan.
Insights
Birth order influences childhood allergies differently. Later birth order increases early asthma risk but decreases it later, while protecting against food allergies but raising atopic dermatitis risk.
Area of Science:
- Pediatric Allergy and Immunology
- Environmental Epidemiology
- Longitudinal Cohort Studies
Background:
- Environmental factors are linked to allergic disease incidence.
- Birth order reflects post-natal environmental exposures.
- Limited longitudinal data exists on birth order and allergies.
Purpose of the Study:
- To investigate the relationship between birth order and allergic diseases.
- To analyze associations with bronchial asthma, food allergy, and atopic dermatitis.
- To understand the impact of birth order on disease development over time.
Main Methods:
- Nationwide longitudinal study of children born in 2001 (n=47,015).
- Analysis of doctor's visits for asthma, food allergy, and atopic dermatitis from infancy to 12 years.
- Binomial log-linear regression adjusting for child and parental factors, estimating risk ratios (RR) and 95% confidence intervals (CI).
Main Results:
- Birth order effects on bronchial asthma varied by age: increased risk in early childhood (RR 1.19, 95% CI 1.05-1.35), decreased risk in later childhood (RR 0.76, 95% CI 0.65-0.89).
- Later birth order was generally protective for food allergy.
- Later birth order increased the risk of atopic dermatitis.
Conclusions:
- The impact of birth order on allergic diseases is disease-specific and age-dependent.
- Childhood immune responses to the post-natal environment are heterogeneous.
- Birth order serves as an indicator of environmental influences on allergic disease development.
Background:
Environmental factors seem to be related to the incidence of allergic disease. Children with a later birth order are often exposed to environments, where pathogens and endotoxins can be found, and thus have a higher risk of developing infectious diseases. Therefore, birth order is regarded as an indicator that reflects post-natal environment. However, longitudinal studies are limited on this subject. This study sought to elucidate the relationships between birth order and allergic disease.
Methods:
From a nationwide longitudinal study that followed children born in 2001 (n = 47 015), we selected doctors' visits for 3 types of allergic disease-bronchial asthma, food allergy and atopic dermatitis-from infancy to 12 years of age and conducted binomial log-linear regression analysis to evaluate the associations between birth order and these diseases. We adjusted for the child and parental factors and estimated risk ratio (RR) and 95% confidence interval (CI) for each outcome.
Results:
The associations between birth order and bronchial asthma were diverse; later birth order increased the risk in early childhood, but decreased the risks during school age. For example, the adjusted RR comparing third-born or higher and first-born children was 1.19 (95% CI, 1.05-1.35) between 30 and 42 months of age, but was 0.76 (95% CI, 0.65-0.89) between 10 and 11 years. Later birth order was generally protective for food allergy but increased the risk of atopic dermatitis.
Conclusion:
The influence of birth order depended on the type of allergic disease and the childhood period. Childhood is unique in terms of physical and immunological development, and the immune response to the post-natal environment in childhood appears to be heterogeneous.
Related Concept Videos
02:06Allergic Reactions
02:16Surveys
02:20Longitudinal Research
01:22Birth Control Methods
01:27Introduction to Surveying, Plane Surveying and Geodetic Surveys
01:30Allergic Reactions: Anaphylaxis