Objective: This study systematically reviewed the scientific literature on the relationship between grandparental child care and childhood obesity. Methods: Keyword/reference search was performed in CINAHL, PsycINFO, PubMed, and Web of Science. Meta-analysis was conducted to estimate the pooled effect of grandparental child care on children's weight outcomes. Results: A total of 23 studies were identified, including 9 longitudinal, 9 cross-sectional, 2 case-control, and 3 qualitative studies. Eight studies were conducted in China, five in Japan, three in the United Kingdom, two in the United States, and one in five other countries each. Twelve studies focused on grandparents' roles as a main caregiver in the family, and seven on grandparents' co-residence. Data from 14 studies were used in meta-analysis, 10 focusing on childhood overweight/obesity and the other 4 on children's BMI z-scores. Meta-analysis found that grandparental child care was associated with a 30% (95% confidence interval = 21-40) increase in childhood overweight/obesity risk. Grandparental child care was not associated with children's BMI z-scores after correcting for publication bias. Meta-regressions revealed no difference in the estimated effect of grandparental child care on children's weight outcomes by country or grandparents' specific roles (main caregiver in the family vs. co-residence). Conclusions: Preliminary evidence links grandparental child care to elevated risk of childhood overweight/obesity, but not BMI z-scores. Future research should focus on a specific child age group within a country, adopt systematic and field-validated measures on grandparental child care, and elucidate the pathways linking grandparental child care to children's weight outcomes.
Keywords: grandparent; meta-analysis; obesity; review.