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Birth weight and body composition in 6-to-8 years old Maya children
Hugo Azcorra1, Maria Inês Varela-Silva2, Federico Dickinson3
1Centro de Investigaciones Silvio Zavala, Universidad Modelo, Mérida, Yucatán, Mexico.
Insights
Higher birth weight in boys is linked to increased fat-free mass index and fat mass index in childhood. These findings suggest sex-specific metabolic adjustments in response to fetal growth.
Area of Science:
- Human growth and development
- Nutritional science
- Pediatric health
Background:
- Fetal growth, indicated by birth weight (BW), may influence later body composition.
- Understanding these early life influences is crucial for long-term health outcomes.
- Previous research has shown mixed associations between birth weight and body composition in children.
Purpose of the Study:
- To investigate the association between fetal growth (birth weight) and body composition in 6-to 8-year-old Maya children.
- To determine if birth weight predicts fat-free mass index (FFMI) and fat mass index (FMI) in childhood.
- To explore potential sex differences in these associations.
Main Methods:
- A sample of 260 urban Maya children (6-8 years) and their mothers were studied in Yucatan, Mexico.
- Children's body composition was assessed using bioelectrical impedance analysis, measuring FFMI and FMI.
- Multiple linear regression models analyzed the relationship between birth weight z-scores and childhood body composition, adjusted for covariates.
Main Results:
- In boys, birth weight was positively associated with both FFMI and FMI.
- A one standard deviation increase in birth weight corresponded to a 0.34 kg/m² increase in FFMI and a 0.40 kg/m² increase in FMI for boys.
- When outcomes were analyzed as z-scores, a one standard deviation increase in birth weight was associated with a 0.24 SD increase in FFMI and a 0.18 SD increase in FMI for boys.
Conclusions:
- The study found a positive association between birth weight and both fat and lean mass in boys, contrary to some previous findings.
- These associations were detected only in boys, suggesting potential sex differences in how early life environments influence development.
- Sex differences in sensitivity to early life factors may explain the observed patterns.
Objective:
To test the hypothesis that fetal growth, indexed by birth weight (BW), induce metabolic adjustments in the fetus that will be reflected in differences in body composition in a sample of 6-to 8-years old urban Maya children from Yucatan, Mexico.
Methods:
We measured height (cm), weight (kg) and triceps skinfold (mm) in 260 children (boys: 132, girls: 128), and height (cm) and weight (kg) in their mothers. Body composition was estimated in children through bioelectrical impedance analysis. Outcome variables were fat free-mass index (FFMI = fat-free mass [kg]/height [m]2 ) and fat mass index (FMI = fat mass [kg]/height [m]2 ). The main independent variable was BW z-scores. Multiple linear regression models were used to analyze the association between BW z-scores and outcome variables measured during childhood. Separate analyses were done for boys and girls. Complementary models were run using outcomes as z-scores. Models were adjusted for location, children's and mothers' age, mother's body mass index and household overcrowding index.
Results:
BW in boys was positively associated with FFMI and FMI. FFMI increase 0.34 kg/m2 per 1-SD increase in BW and FMI increase 0.40 kg/m2 per 1-SD increase in BW. When outcomes were used as z-scores, FFMI increase 0.24 SD and FMI increase 0.18 SD per 1-SD increase in BW, respectively.
Conclusion:
Our results are in contrast with previous findings that birth weight is more consistently associated with subsequent lean mass than with fat mass. Associations, detected only in boys, may be explained by sex differences in sensitivity to early life environments.
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