Cross-national Comparison Examining Breastfeeding and Child Malnutrition among Mexicans
Child malnutrition, including overweight and stunting, is a public health concern that affects millions of families worldwide causing short- and long-term health, social and economic inequalities. The global prevalence of child overweight has increased over the past decades in countries across the economic spectrum. In contrast, the prevalence of child stunting has decreased globally yet remains the most prevalent form of child malnutrition commonly affecting children in the most vulnerable conditions in low- and middle-income countries (LMICs). Global initiatives have been adopted in response to the high burden of child malnutrition. In order to support these initiatives, researchers have focused on informing evidence-based, affordable and effective policies and interventions to prevent child malnutrition mostly within the programmatic timeframe of the first 1,000 days, conception through the first 2 years of life, and beyond. Breastfeeding has been identified as one of the key affordable and modifiable maternal health behaviors protecting against child malnutrition. However, the protective effect of breastfeeding on child malnutrition has been discrepant across findings from LMICs and high-income countries (HICs). These inconsistencies may be due to differential contextual factors in LMICs and HICs. Theoretically grounded in the World Health Organization (WHO) conceptual models on social determinants of health and childhood stunting, as well as in the Dahlgren and Whitehead model, and cultural perspectives, the goal of this 3-paper dissertation was to assess the effect of breastfeeding duration and individual, household and area factors on child malnutrition among Mexican children aged 0 to 35 months living in México (a LMIC) and in the US (a HIC). Paper 1, hereon referred to as chapter 2, assessed the association between breastfeeding duration and child overweight while sequentially controlling for individual, household and area factors in Mexican children, and also assessed a 2-level mixed-effects logistic model accounting for households clustered within areas. We curated a subset from the 2012 Mexican National Health and Nutrition Survey (ENSANUT). We found evidence for an association between breastfeeding duration and child overweight, and maternal obesity and offspring high birthweight were consistent risk factors for child overweight across models, suggesting genetic and shared environment influences. Paper 2, hereon referred to as chapter 3, used the same subset but incorporated relevant risk factors for child stunting while using the same analytical approach. We found no evidence for an association between breastfeeding duration and child stunting. However, children who were never breastfed were at higher odds for stunting compared to those breastfed <6 months. Consistent risk factors for child stunting across models were increased child age, being male, child low birthweight, maternal ethnicity (self-identifying as indigenous), maternal short stature, higher count of children aged <5 years per household, and household moderate to severe food insecurity. These findings support the intergenerational effect of early stunting and the burden of food insecurity, perpetuating the cycle of inequalities. Paper 3, hereon referred to as chapter 4, incorporated a binational approach examining the effects of breastfeeding duration and individual and household factors on child malnutrition in Mexican-American children, and then compared results with Mexican children by running separate and pooled analyses. Besides using the ENSANUT 2012 subset, we curated a new dataset using 4 waves of the 2007-2014 National Health and Nutrition Examination Survey (NHANES) which provided data for Mexican-American children aged 0 to 35 months. ENSANUT variables were recoded to match NHANES subset. We found a protective effect of breastfeeding duration on child overweight among Mexicans and in the pooled dataset. The only consistent risk factor for child overweight among Mexican and Mexican-Americans was high birthweight. Regarding child stunting, we found no evidence for an association with breastfeeding duration but low birthweight was a risk factor across both populations, while being male and living in moderate to severe food insecure households were risk factors only for Mexican children. In general, findings from this chapter coincide with previously described patterns meaning that child stunting was mostly prevalent in LMICs such as México, and that country of residence and cultural perspectives were relevant when examining child malnutrition among Mexican immigrants. Altogether, results advance the knowledge base by providing a comparison of Mexicans sharing a nurturing system while living in 2 different sustaining systems, a LMIC- and HIC-context. Findings provide evidence for shared risk factors for child malnutrition across Mexicans in both countries as well as identifying country-specific factors. While we acknowledge that the cross-sectional design of both surveys, from which we curated our subsets, limit our ability to infer causality, these results have pertinent policy and intervention implications. Pre- and post-natal culturally-sensitive components in policies and interventions need to be aimed towards preventing proximal and distal risk factors for child malnutrition within the first 1,000 days and beyond, including the promotion and support of positive maternal health behaviors such as breastfeeding.