Breastfeeding is one of the most effective ‘interventions’ for reducing infant mortality. Despite ongoing efforts to promote breastfeeding, current breastfeeding rates in the U.S. are still low, and socioeconomic and racial/ethnic disparities in breastfeeding practices have persisted. Improving breastfeeding practices among socially disadvantaged groups remains challenging. The goal of this dissertation is to improve breastfeeding rates and reduce racial/ethnic disparities in breastfeeding practices in the United States. Specifically, this dissertation aims to: (1) assess the influences of breastfeeding support from family, hospitals and workplaces on breastfeeding duration; (2) determine the extent to which racial/ethnic disparities in breastfeeding duration could be explained by breastfeeding support; and (3) estimate the population impact of multifaceted breastfeeding promotion interventions. Using data on approximately 4,000 mothers enrolled in the Special Supplemental Nutrition Program for Women, Infants and Children (WIC), from the triennial Los Angeles County WIC Survey (2014, 2017), this dissertation found that breastfeeding support from family, hospitals and workplaces was significantly associated with longer breastfeeding duration, and that Black mothers and English-speaking Latina mothers have significantly lower breastfeeding rates than White mothers, with the difference widening over increasing duration. Results from causal mediation analysis (specifically, g-computation) showed that lack of access to breastfeeding support from family, hospitals and workplaces accounted for approximately two-thirds of the difference in breastfeeding duration between White and Black mothers, and one-third of the difference between White and English-speaking Latina mothers. This dissertation also illustrated the use of agent-based modeling (ABM) for estimating the population impact of five selected breastfeeding promotion interventions (improving knowledge, implementing Baby-Friendly Hospital Initiative practices, providing breastfeeding counseling, strengthening family support, and fostering supportive workplace environments) implemented singly or in combination with each other. The ABM demonstrated that while improving knowledge and increasing the availability of Baby-Friendly Hospital Initiative practices improve breastfeeding initiation rates, breastfeeding counseling, family support and a supportive workplace environment are more effective in improving breastfeeding duration. Increasing the coverage of multiple interventions simultaneously had a synergistic effect on breastfeeding duration, with their effects being greater than the additive effects of increasing the coverage of these interventions singly.

The prevalence of early childhood obesity is increasing rapidly in China. Grandparents have been blamed by public media for facilitating the trend through overfeeding and spoiling their grandchildren. However, researches are scarce on the role of grandparental caregiving in obesity among preschoolers. This empirical study aimed to assess the impacts of grandparental caregiving on obesity among children aged 0-5 years taking into consideration other contextual factors such as family socioeconomic status and neighborhood environment.

Drawn data of 686 children aged 0-5 years old and their families from the China Health and Nutrition Survey in the year 2011, this study compared obesity-related knowledge and practices of grandparents with parents, and contrasted the prevalence of obesity and obesogenic behaviors among children in three types of family living arrangements which reflect a gradient amount/level of grandparents’ involvement in caregiving: nuclear families, three-generation families and skipped-generation families.

The results showed that grandparental caregiving is not associated with increased risk of obesity among preschoolers. Compared with parents, grandparents were less aware of national nutrition guideline (18.5% vs 30.0%, p<0.01), had lower nutrition knowledge score (8.4 vs 8.9, p<0.01), and watched television longer per day (120 vs 105 mins, p<0.01). However, there was no difference in dietary intake among children in three types of living arrangement. The length of daily television watching was the shortest for children in three-generation families (54.4 ? 62.1mins), and the longest for children in skipped-generation family (71.8 ?76.2 minutes). Children in three-generation families, taken care of by both parents and grandparents showed significantly lower weight-for-height Z-scores than those in nuclear families, taken care of only by parent(s) (p<0.01). After controlling for other factors (child’s age and gender, household income, education level of caregivers, enrollment in childcare, neighborhood urbanization index, and type of neighborhood) , children in three-generation families still exhibited the significant lower mean weight-for-height Z-scores than those in nuclear families and in skipped-generation families. One individual characteristic factor (child’s age) and one contextual factor (type of neighborhood) were also significantly associated with child’s weight-for-height Z-score.

This study concluded that grandparental caregiving does not increase the risk of obesity for preschoolers. Instead, children in the care of grandparents in three-generation families are at lower risk than those cared for only by parent(s) or only by grandparent(s). Further researches are needed to explore the mechanism or the interactions in three-generation families which form a healthier environment for preschoolers so as to inform family-oriented program planning and policy design regarding early childhood obesity prevention.

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