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Updated: Jun 13, 2026

Assessment of Child Anthropometry in a Large Epidemiologic Study
Published on: February 2, 2017
Family structure and childhood obesity, Early Childhood Longitudinal Study - Kindergarten Cohort
1Children's Hospital Los Angeles, Division of Research on Children, Youth, and Families, 4650 Sunset Blvd, MS #30, Los Angeles, CA 90027, USA. achen@chla.usc.edu
Insights
Children in single-mother families and those with no siblings face higher childhood obesity risks. Family structure significantly impacts a child's body mass index (BMI) and obesity development.
Area of Science:
- Pediatrics
- Public Health
- Family Studies
Background:
- Childhood obesity is a growing concern in the US.
- The impact of family structure on childhood obesity remains understudied.
- Understanding family dynamics is crucial for addressing obesity prevention.
Purpose of the Study:
- To investigate the association between family structure and childhood obesity.
- To examine the influence of the number of parents and siblings on children's BMI and obesity risk.
- To analyze longitudinal changes in BMI based on family composition.
Main Methods:
- Secondary data analysis of the Early Childhood Longitudinal Study - Kindergarten Cohort (ECLS-K).
- Inclusion of a nationally representative sample of US children.
- Assessment of cross-sectional and longitudinal outcomes including measured Body Mass Index (BMI) and obesity status.
Main Results:
- Children in single-mother households showed a higher likelihood of obesity by fifth grade compared to those in two-parent homes.
- Children with siblings had lower BMI and reduced obesity risk than children without siblings.
- Living with a single mother or having no siblings correlated with greater BMI increases from kindergarten to fifth grade.
Conclusions:
- Single-mother families and lack of siblings are associated with increased childhood obesity risk.
- Family structure plays a significant role in the development of childhood obesity.
- Healthcare providers should consider family structure when discussing obesity with families.
Introduction:
Little is known about the effect of family structure on childhood obesity among US children. This study examines the effect of number of parents and number of siblings on children's body mass index and risk of obesity.
Methods:
We conducted a secondary data analysis of the Early Childhood Longitudinal Study - Kindergarten Cohort (ECLS-K), which consists of a nationally representative cohort of children who entered kindergarten during 1998-1999. Our analyses included 2 cross-sectional outcomes and 1 longitudinal outcome: body mass index (BMI) calculated from measured height and weight, obesity defined as BMI in the 95th percentile or higher for age and sex, and change in BMI from kindergarten through fifth grade.
Results:
Other things being equal, children living with single mothers were more likely to be obese by fifth grade than were children living with 2 parents (26% vs 22%, P = .05). Children with siblings had lower BMI and were less likely to be obese than children without siblings. We also found that living with a single mother or no siblings was associated with larger increases in BMI from kindergarten through fifth grade.
Conclusion:
Children from single-mother families and, especially, children with no siblings are at higher risk for obesity than children living with 2 parents and children with siblings. These findings highlight the influential role that families play in childhood obesity. Additionally, they suggest that health care providers should consider the structure of children's families in discussions with families regarding childhood obesity.
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