Birth order and sibship composition as predictors of overweight or obesity among low-income 4- to 8-year-old children.
OBJECTIVE
This study aimed to examine the association of birth order and number and sex of siblings with overweight or obesity among 4- to 8-year-olds.


METHODS
This is a cross-sectional study involving 273 low-income mother-child dyads. Questionnaires and anthropometry were completed. Multiple logistic regression was used to examine the association of birth order, having younger siblings, having older siblings, having at least one brother and having at least one sister with odds of overweight or obesity. Analyses were repeated to additionally include non-biological siblings. Models were adjusted for potential confounders and intermediate variables.


RESULTS
Prevalence of child overweight or obesity was 42.5%. Adjusting for covariates, only children and youngest siblings had higher odds of overweight or obesity compared with oldest siblings (odds ratio [OR]: 4.18, 95% confidence interval [CI]: 1.67, 10.46 and OR: 3.21, 95% CI: 1.41, 7.33, respectively). Having one or more younger siblings and having at least one brother were associated with lower odds (OR: 0.38, 95% CI: 0.21, 0.69 and OR: 0.47, 95% CI: 0.28, 0.81, respectively). Including non-biological siblings did not meaningfully change the associations.


CONCLUSIONS
Birth order and sibship composition are associated with overweight or obesity among 4- to 8-year-olds. Future studies identifying the underlying behavioural mechanism can help inform family-based intervention programmes.
Human Nutrition Program, Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI, USA.|Clinical Nutrition Department, Faculty of Applied Medical Sciences, King Abdulaziz University, Jedddah, KSA.
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Mosli
Department of Health Behavior and Health Education, School of Public Health, University of Michigan, Ann Arbor, MI, USA.|Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, USA.
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Miller
Human Nutrition Program, Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI, USA.|Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, USA.|Department of Nutrition, Harvard School of Public Health, Boston, MA, USA.
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Peterson
Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, USA.
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Kaciroti
Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, USA.|Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA.
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Rosenblum
Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI, USA.
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A
Baylin
Human Nutrition Program, Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI, USA.|Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, USA.|Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI, USA.
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Lumeng
D001722:Birth Order / Q000523:psychology; D001823:Body Composition; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D016017:Odds Ratio; D050177:Overweight / Q000453:epidemiology* / Q000523:psychology; D011203:Poverty; D011237:Predictive Value of Tests; D015995:Prevalence; D012307:Risk Factors; D035781:Siblings; D011795:Surveys and Questionnaires
Birth order; odds of overweight or obesity; sibship composition