Breastfeeding and Childhood Obesity: Shift of the Entire BMI Distribution or Only the Upper Parts?

Abstract

A protective effect of breastfeeding on overweight (binary) has been reported by meta‐analyses using logistic regression, whereas studies using linear regression and BMI (continuous) detected no significant association. To assess the relationship of these differences with different outcome classification, we compared results for linear, logistic, and quantile regression models in a cross‐sectional data set of considerable size. Height, weight, and questionnaire data on 9,368 preschool children were collected during school‐entry examinations in 1999 and 2002 in Bavaria, Southern Germany. We calculated multivariable linear, logistic, and quantile regression models with outcomes BMI, overweight, obesity, and BMI quantiles (as appropriate). Models considered the covariates breastfeeding (breastfed vs. never breastfed), gender, age, smoking in pregnancy, TV watching, maternal BMI, parental education, and early infant weight gain. No significant association was found in the linear regression model. In the logistic model, a significant association was observed for obesity (odds ratio: 0.72 (95% confidence interval (CI) 0.55, 0.94)). In quantile regression no significant point estimates were observed for the percentiles of 0.4–0.8. However, breastfeeding reduced the BMI of children having values on the 90th and 97th percentiles by −0.23 (95% CI −0.39, −0.07) and −0.26 (95% CI −0.45, −0.07) kg/m2, respectively, on average. In contrast, breastfeeding was significantly associated with a low shift toward higher BMI values for BMI quantiles of 0.03 and from 0.1 to 0.3. The detection of associations between breastfeeding and childhood body composition might be related to the coding of the response variable (continuous or binary) and the statistical method used (linear, logistic, or quantile regression). Quantile regression should additionally be applied in such studies.

Risk factors for childhood overweight: shift of the mean body mass index and shift of the upper percentiles: results from a cross-sectional study

“…Therefore, breastfeeding seems to be a useful public health strategy to prevent overweight and obesity without affecting underweight children in terms of weight reduction. 33 These findings may provide an explanation for the consistently observed trend to more extreme BMI values in children from high-income countries over recent years. [6][7][8][9] If risk factors of overweight affect particularly children with high BMI-SDS (making them even heavier), incremental exposure to those risk factors would primarily result in more extreme values of BMI in the upper part of the distribution.…”

Early Influences of Nutrition on Postnatal Growth

“…However, it is important to note that this trial did not have sufficient statistical power to answer the question of a protective effect of breastfeeding relative to formula feeding, because rates of breastfeeding were relatively similar in the intervention and control groups, and the prevalence of obesity was low in this population [56]. Of interest, Beyerlein and von Kries [56] and Beyerlein et al [57] found evidence that breastfeeding reduces particularly the proportion of subjects with a high BMI at later ages, while having little effect on the mean BMI.…”

Interactions of genetic and environmental risk factors with respect to body fat mass in children: Results from the ALSPAC study

“…These were dichotomized in order to compare FMI distributions in exposed and non-exposed children. Maternal smoking during pregnancy and exclusive formula feeding are established priming factors for childhood overweight (19,20). As factors associated with life-style, we chose low physical activity (defined as child goes to special classes or clubs for some activity (e.g., dancing, judo, sports) less than once a week), high TV consumption (defined as more than 2 hours per day), both at the age of 9 years, and low parental education (i.e., neither father nor mother achieved O-level).…”

“…We selected environmental variables if they had shown a distribution dependent effect on children's BMI (19,20) or by a priori considerations. These were dichotomized in order to compare FMI distributions in exposed and non-exposed children.…”