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The influence of birth order and number of siblings on adolescent body composition: evidence from a Brazilian birth cohort study.

de Oliveira Meller F, Assunção MC, Schäfer AA, de Mola CL, Barros AJ, Dahly DL, Barros FC - Br. J. Nutr. (2015)

Bottom Line: In adjusted models, the total siblings remained inversely associated with fat mass index (β = - 0.37 z-scores, 95 % CI - 0.52, - 0.23) and BMI in boys (β = - 0.39 z-scores, 95 % CI - 0.55, - 0.22).Fat-free mass index was related to the total siblings in girls (β = 0.06 z-scores, 95 % CI - 0.04, 0.17).This research has found that number of total siblings, and not birth order, is related to the fat mass index, fat-free mass index and BMI in adolescents.

View Article: PubMed Central - PubMed

Affiliation: Post-Graduate Program in Epidemiology, Federal University of Pelotas,Pelotas,Brazil.

ABSTRACT
The aim of this study was to estimate the association between birth order and number of siblings with body composition in adolescents. Data are from a birth cohort study conducted in Pelotas, Brazil. At the age of 18 years, 4563 adolescents were located, of whom 4106 were interviewed (follow-up rate 81.3 %). Of these, 3974 had complete data and were thus included in our analysis. The variables used in the analysis were measured during the perinatal period, or at 11, 15 and/or 18 years of age. Body composition at 18 years was collected by air displacement plethysmography (BOD POD®). Crude and adjusted analyses of the association between birth order and number of siblings with body composition were performed using linear regression. All analyses were stratified by the adolescent sex. The means of BMI, fat mass index and fat-free mass index among adolescents were 23.4 (sd 4.5) kg/m², 6.1 (sd 3.9) kg/m² and 17.3 (sd 2.5) kg/m², respectively. In adjusted models, the total siblings remained inversely associated with fat mass index (β = - 0.37 z-scores, 95 % CI - 0.52, - 0.23) and BMI in boys (β = - 0.39 z-scores, 95 % CI - 0.55, - 0.22). Fat-free mass index was related to the total siblings in girls (β = 0.06 z-scores, 95 % CI - 0.04, 0.17). This research has found that number of total siblings, and not birth order, is related to the fat mass index, fat-free mass index and BMI in adolescents. It suggests the need for early prevention of obesity or fat mass accumulation in only children.

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Related in: MedlinePlus

Conceptual model of association between birth order, number of siblings and body composition at 18 years of age. The 1993 Pelotas Birth Cohort, Brazil.
© Copyright Policy - open-access
Related In: Results  -  Collection


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fig1: Conceptual model of association between birth order, number of siblings and body composition at 18 years of age. The 1993 Pelotas Birth Cohort, Brazil.

Mentions: To evaluate the relative importance of birth order and number of siblings, we compared the fit of three different models based on their respective R2, adjusted R2, Akaike's information criterion and mean squared error. In model 1, only birth order and number of younger siblings were included as independent variables. In model 2, we included these variables plus potential confounders (Fig. 1). Model 3 included the total siblings (which is equal to the birth order plus the number of younger siblings, less one), and the confounding variables of model 2. The purpose of this third model was to evaluate if the position of the adolescent in the family influences the body composition, or whether this association is rather due to the number of siblings. The model that presented the best fit was the one with higher values of R2 and adjusted R2, and lower values of Akaike's information criterion and mean squared error.Fig. 1


The influence of birth order and number of siblings on adolescent body composition: evidence from a Brazilian birth cohort study.

de Oliveira Meller F, Assunção MC, Schäfer AA, de Mola CL, Barros AJ, Dahly DL, Barros FC - Br. J. Nutr. (2015)

Conceptual model of association between birth order, number of siblings and body composition at 18 years of age. The 1993 Pelotas Birth Cohort, Brazil.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4530600&req=5

fig1: Conceptual model of association between birth order, number of siblings and body composition at 18 years of age. The 1993 Pelotas Birth Cohort, Brazil.
Mentions: To evaluate the relative importance of birth order and number of siblings, we compared the fit of three different models based on their respective R2, adjusted R2, Akaike's information criterion and mean squared error. In model 1, only birth order and number of younger siblings were included as independent variables. In model 2, we included these variables plus potential confounders (Fig. 1). Model 3 included the total siblings (which is equal to the birth order plus the number of younger siblings, less one), and the confounding variables of model 2. The purpose of this third model was to evaluate if the position of the adolescent in the family influences the body composition, or whether this association is rather due to the number of siblings. The model that presented the best fit was the one with higher values of R2 and adjusted R2, and lower values of Akaike's information criterion and mean squared error.Fig. 1

Bottom Line: In adjusted models, the total siblings remained inversely associated with fat mass index (β = - 0.37 z-scores, 95 % CI - 0.52, - 0.23) and BMI in boys (β = - 0.39 z-scores, 95 % CI - 0.55, - 0.22).Fat-free mass index was related to the total siblings in girls (β = 0.06 z-scores, 95 % CI - 0.04, 0.17).This research has found that number of total siblings, and not birth order, is related to the fat mass index, fat-free mass index and BMI in adolescents.

View Article: PubMed Central - PubMed

Affiliation: Post-Graduate Program in Epidemiology, Federal University of Pelotas,Pelotas,Brazil.

ABSTRACT
The aim of this study was to estimate the association between birth order and number of siblings with body composition in adolescents. Data are from a birth cohort study conducted in Pelotas, Brazil. At the age of 18 years, 4563 adolescents were located, of whom 4106 were interviewed (follow-up rate 81.3 %). Of these, 3974 had complete data and were thus included in our analysis. The variables used in the analysis were measured during the perinatal period, or at 11, 15 and/or 18 years of age. Body composition at 18 years was collected by air displacement plethysmography (BOD POD®). Crude and adjusted analyses of the association between birth order and number of siblings with body composition were performed using linear regression. All analyses were stratified by the adolescent sex. The means of BMI, fat mass index and fat-free mass index among adolescents were 23.4 (sd 4.5) kg/m², 6.1 (sd 3.9) kg/m² and 17.3 (sd 2.5) kg/m², respectively. In adjusted models, the total siblings remained inversely associated with fat mass index (β = - 0.37 z-scores, 95 % CI - 0.52, - 0.23) and BMI in boys (β = - 0.39 z-scores, 95 % CI - 0.55, - 0.22). Fat-free mass index was related to the total siblings in girls (β = 0.06 z-scores, 95 % CI - 0.04, 0.17). This research has found that number of total siblings, and not birth order, is related to the fat mass index, fat-free mass index and BMI in adolescents. It suggests the need for early prevention of obesity or fat mass accumulation in only children.

Show MeSH
Related in: MedlinePlus