Review Article
Free access
Published Online: 19 March 2020

Influence of Grandparental Child Care on Childhood Obesity: A Systematic Review and Meta-Analysis

Publication: Childhood Obesity
Volume 16, Issue Number 3

Abstract

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.

Introduction

Obesity is a leading cause of morbidity and premature mortality worldwide.1–4 Childhood obesity is linked to various immediate and long-term adverse health outcomes such as sleep apnea, hypertension, heart disease, stroke, type 2 diabetes, osteoarthritis, and certain types of cancer, and it leads to social and psychological problems such as stigmatization and poor self-esteem.5,6 In 2010, 43 million children worldwide (35 million in developing countries) were estimated to be overweight or obese.7 The prevalence of childhood overweight/obesity is projected to reach 9% or 60 million children in 2020.8
As obesity is a result of energy imbalance, healthful diet and physical activity are the core of childhood obesity prevention effort.9 Family-based interventions are a key strategy in promoting these healthy lifestyle behaviors, given family's highly influential role in supporting and managing children's energy balance through parenting practices and the family environment.10,11 Family-based interventions have conventionally included parents as an integral target. There is a proliferation of original studies and reviews focused on the roles of parents in childhood obesity and family-based interventions involving parents.12 Less attention is placed on the influence of other caregivers in the family, such as grandparents.
A secondary analysis of nationally representative survey data found that children with normal-weight parents and obese grandparents had twice the risk of being overweight themselves than children with normal-weight parents and normal-weight grandparents,13 suggesting that grandparents had an influence on child weight status distinct from parental influence. Demographic shifts (e.g., increased life expectancy) and changes in family structures (e.g., the rise of single-parent households and working moms) have seen an increase in the number of grandparents who provide extensive child care to their grandchildren.14 Today's grandparents are more than occasional visitors and gift bearers, but play an essential role in raising the next generation.
In the United States, grandparents care for as many children as formal child care programs do: almost one in four children under age 5 were routinely cared for by a grandparent, while parents worked or attended school.15 In many developing countries such as China, grandparental child care is even more prevalent and plays more significant roles in child care. Grandparents routinely perform activities ranging from getting young children ready for school in the morning, grocery shopping with them, planning and cooking family meals, and taking them to the playground to providing full-time child care for preschoolers and acting as the custodial parent to children whose parents are unwilling or unable to provide care.16,17
Such activities transform the grandparent from the more traditional older-generation-in-the-family roles into roles typically assumed by a child's parents, and in some cases, grandparent becomes the primary caregiver.18 As grandparents increasingly assume the role of parents in children's lives, they exert more influence over children's diet, physical activity, and other behaviors (e.g., sleep) that affect energy balance.19–21
The rising awareness among researchers regarding the important roles of grandparents has resulted in an increase in the number of studies that examined the relationship between grandparental child care and childhood obesity.22–25 Findings from these studies remain inconclusive: some studies reported a higher risk of childhood obesity among children cared for by grandparents than those under parental care only22,26,27 and some reported null findings,28 whereas some suggested the positive impact of grandparental child care on reducing childhood obesity through contributing to a more balanced diet29 and increased physical activity among children.19
To identify patterns in research findings and gaps in knowledge, we conducted a systematic review and meta-analysis to appraise and synthesize quantitative studies on the relationship between grandparental child care and childhood obesity. To our knowledge, there has not yet been a systematic review and meta-analysis focusing on the role of grandparental child care on children's body weight. Such reviews are both important and timely, given the increased number of grandparents routinely providing child care and studies investigating the link between grandparental child care and childhood obesity. Findings from such reviews will identify targets for intervention, help refine existing family-based interventions, and inform future research and practice to combat childhood obesity.

Methods

Study Selection Criteria

Studies that met all of the following criteria were included in the review: (1) study design: observational studies (e.g., longitudinal studies, case–control studies, or cross-sectional studies) or qualitative studies; (2) study subjects: children 17 years of ages and younger; (3) exposure: grandparental child care; (4) outcomes: body weight status (e.g., BMI percentile or z-score, or childhood overweight or obesity); (5) article type: peer-reviewed publications; (6) time window of search: from the inception of an electronic bibliographic database to July 15, 2019; (7) geographical location: worldwide; and (8) language: articles written in English.
Studies that met any of the following criteria were excluded from the review: (1) studies that incorporated no outcome pertaining to children's body weight status; (2) exposures without grandparental child care; (3) articles not written in English; or (4) letters, editorials, study/review protocols, or review articles.

Search Strategy

A keyword search was performed in four electronic bibliographic databases: CINAHL, PsycINFO, PubMed, and Web of Science. The search algorithm is provided in Table 1. Titles and abstracts of the articles identified through the keyword search were screened against the study selection criteria. Potentially relevant articles were retrieved for evaluation of the full text. Two co-authors of this review independently conducted title and abstract screening and identified potentially relevant articles. Inter-rater agreement was assessed using the Cohen's kappa (κ = 0.82). Discrepancies were resolved through discussion under the participation of a third co-author.
Table 1. Search Algorithm
GroupKeywords
Grandparent-related“grandparent,” “grandparents,” “grand parent,” “grand-parent,” “grandparental,” “grandparenthood,” “grand-paternal,” “grandpaternal,” “grand paternal,” “grandmother,” “grandmothers,” “grand mother,” “grand-mother,” “grandmotherhood,” “grandma,” “grandfather,” “grandfathers,” “grand father,” “grand-father,” “grandpa,” “grandfatherhood,” “grandmaternal,” “grand maternal,” “intergenerational,” “grandfamily,” “grandfamilies,” “grand family,” “grand families,” “multigenerational,” “multi-generational,” “multigeneration,” “multi generations,” “grandparenting,” “grandparent-headed,” “three generations,” “three-generation,” “older generation,” “older generations,” “cross-generation,” or “kinship”
Obesity-related“obesity,” “obese,” “adiposity,” “overweight,” “body mass index,” “BMI,” “body weight,” “waist circumference,” “waist to hip,” “waist-to-hip,” or “body fat”
Grandchild-related“child,” “children,” “childhood,” “juvenile,” “pubescent,” “pubertal,” “puberty,” “adolescent,” “adolescents,” “adolescence,” “youth,” “teen,” “teens,” “teenage,” “teen-age,” “teenaged,” “teen-aged,” “teenager,” “teenagers,” “teen-ager,” “teen-agers,” “kid,” “kids,” “youngster,” “youngsters,” “minor,” “minors,” “student,” “students,” “preschooler,” “preschoolers,” “grandchild,” “grand child,” “grandchildren,” “granddaughter,” “grand daughter,” “grand son,” or “grandson”
A reference list search (i.e., backward reference search) and a cited reference search (i.e., forward reference search) were conducted based on the full-text articles meeting the study selection criteria that were identified from the keyword search. Articles identified from the backward and forward reference search were further screened and evaluated using the same study selection criteria. Reference search was repeated on all newly identified articles until no additional relevant article was found.

Data Extraction and Preparation

A standardized data extraction form was used to collect the following methodological and outcome variables from each included study: first author, publication year, country, year of study, study design, sample age group, sample size, age range, proportion of female participants, statistical model, nonresponse rate, urbanicity, family role of grandparents, type of body weight status measure, detailed measure of body weight status, estimated effects of grandparental child care on body weight status, and secondary outcomes (e.g., physical activity and/or diet).

Meta-Analysis

Meta-analysis was performed to estimate the pooled effect of grandparental child care on children's body weight status. Separate models were estimated for the two outcomes: childhood overweight/obesity and the BMI z-score. For the outcome of childhood overweight/obesity, studies were selected for meta-analysis if they reported the estimated risk ratios and/or odds ratios for childhood overweight/obesity. For the outcome of BMI z-scores, studies were selected for meta-analysis if they reported the estimated coefficients for BMI z-scores. Study heterogeneity was assessed using the I2 index. The level of heterogeneity represented by the I2 index was interpreted as small (I2 ≤ 25%), moderate (25% < I2 ≤ 50%), large (50% < I2 ≤ 75%), or very large (I2 > 75%).
A fixed-effect model was performed when the heterogeneity level was small or moderate, whereas a random-effect model was performed when the heterogeneity level was large or very large. Random-effect meta-regressions were conducted to assess the potential moderating effects of country and type of care (caregiving vs. co-residence) on the relationship between grandparental child care and children's body weight status. Publication bias was evaluated using funnel plot and Begg's and Egger's tests.30 A nonparametric trim-and-fill method would be used to correct for publication bias if either Begg's or Egger's test was statistically significant (i.e., p < 0.05). All statistical analyses were performed using Stata 15.1 SE version (StataCorp, College Station, TX).

Study Quality Assessment

We used the National Institutes of Health's Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies to assess the quality of each included study.31 This assessment tool rates each study based on 14 criteria. For each criterion, a score of 1 was assigned if “yes” was the response, whereas a score of 0 was assigned otherwise. A study-specific global score ranging from 0 to 14 was calculated by summing up scores across all criteria. The study quality assessment helped measure the strength of scientific evidence, but was not used to determine the inclusion of studies.

Results

Identification of Studies

Figure 1 shows the study selection flow chart. We identified a total of 2109 articles through the keyword and reference search. After removing duplications, 1609 unique articles underwent title and abstract screening, in which 1584 articles were excluded. The full texts of the remaining 25 articles were reviewed against the study selection criteria. Of these, two articles were excluded. The primary reasons for exclusion are lack of outcome pertaining to childhood obesity and adult sample instead of children and/or adolescents. The remaining 23 studies that examined the relationship between grandparental child care and children's body weight status were included in the review.16,17,19–29,32–41 Fourteen studies were included in the meta-analyses, as shown in Table 4 (4 studies on BMI z-scores32,33,37,38 and 10 studies on childhood overweight/obesity risk19,22–26,28,34–36).
Figure 1. Study selection flowchart.

Basic Characteristics of the Included Studies

Table 2 summarizes the basic characteristics of the 23 included studies. Eight studies were conducted in China, five in Japan, three in the United Kingdom, two in the United States, and one each in Greek, European countries, Central African Republic, Sweden, and Turkey. All included studies were published in or after 2010—one in 2014, two each in 2010 and 2011, three each in 2018 and 2019, and four each in 2013, 2015, and 2017. Two studies adopted a case–control study design, three adopted a qualitative study design, nine adopted a longitudinal study design, and the remaining nine adopted a cross-sectional study design.
Table 2. Basic Characteristics of the Studies Included in the Review
Study IDReferncesCountryYear of studyStudy designAge groupSample sizeAge, yearsFemale, %Statistical modelAttrition, %Urbanicity
1Moschonis et al22Greek2007Cross-sectionalChildren7299–1348Logistic regression Urban
2Pearce et al.23United Kingdom2000–2002LongitudinalInfants123540–3 Poisson regression20.0 
3de Brauw and Mu24China1997, 2000, 2004, 2006LongitudinalChildren9822–12 Fixed effects36.4Rural
4Watanabe et al.34Japan2003Cross-sectionalChildren18673–648Logistic regression16.5Urban
5Pulgarón et al.17United States Cross-sectionalChildren1997.79 ± 1.7253ANOVA Urban
6Tanskanen25United Kingdom2003–2005LongitudinalChildren90003.14 ± 0.21 Logistic regression  
7Formisano et al.377 European countries2007–2010LongitudinalChildren52365.9 ± 1.849ANCOVA49.1 
8Li et al.19China2009, 2010Cross-sectionalChildren4978–1068Logistic regression2.2Urban
9Meehan et al.29Central African Republic2009–2012Cross-sectionalChildren127<1049OLS  
10Li et al.21China2009, 2010Focus group, cross-sectionalChildren4978–10 OLS Urban
11Sata et al.33Japan1992LongitudinalChildren42816, 12, and 2248Mixed effects63.6Urban
12Zong et al.26China1996, 2006Case–controlChildren1996: 1844; 2006: 32983–71996: 33; 2006: 31Conditional logistic regression Urban
13Lindberg et al.39Sweden2012–2014Cross-sectionalChildren394–656OLS25.0Urban
14Ikeda et al.35Japan2001LongitudinalChildren430462.5–1348Random effects logit regression1.6Urban, rural
15Li et al.20China2013, 2014Focus groupChildren148  Inductive thematic analysis Urban
16Li et al.27China2014–2017Cross-sectionalInfants25143, 6, 9, and 12 months47ANOVA2.7 
17Wei et al.32China2015Cross-sectionalChildren8573–549OLS15.1Urban
18He et al.16China1991, 1993, 1997, 2000, 2004, 2006, 2009, 2011LongitudinalChildren128792–13 Instrumental variable Urban, rural
19Lidgate et al.40United Kingdom2016, 2017Focus groupInfants, children140–5 Inductive thematic analysis Urban
20Metbulut et al.41Turkey2015, 2016Case–controlChildren2002–549Spearman correlation  
21Ikeda and Nishi36Japan2001LongitudinalChildren154273.5–1249Logistic regression67.2Urban, rural
22Lau et al.28United States2015Cross-sectionalChildren, adolescents120292–1947Logistic regression2.0Urban
23Morita et al.38Japan2015, 2016LongitudinalChildren34187.1 ± 0.349Poisson regression7.2Urban
Seven European countries include Italy, Belgium, Cyprus, Estonia, Germany, Hungary, Spain, and Sweden; the classification of age groups: 0–2 years—infants, 3–11 years—children, and 12–17 years—adolescents.
ANCOVA, analysis of covariance; ANOVA, analysis of variance; OLS, ordinary least squares.
Sample sizes were generally large, but varied substantially across studies. Two studies had a sample size between 10 and 99, nine had a sample size between 100 and 999, seven had a sample size between 1000 and 9999, and the remaining five had a sample size above 10,000. The mean and median sample sizes were 5636 and 1867, respectively, with a standard deviation of 9500 and a range from 14 to 43,046.
We categorized the study samples by age groups—infants 0–2 years of age, children 3–11 years of age, and adolescents 12–17 years of age. Two studies recruited infants, the majority (n = 19) of studies recruited children, one recruited both infants and children, and the remaining one recruited both children and adolescents. All included studies recruited both girls and boys, largely equally distributed in the samples. A variety of statistical models were applied across studies, including Spearman's correlation coefficient, linear regression, logistic regression, conditional logistic regression, Poisson regression, fixed-effect model, mixed-effect model, ANOVA, and ANCOVA. The majority of studies (n = 16) adjusted for some individual sociodemographic and/or family characteristics in the statistical analysis.

Key Findings of the Included Studies

Table 3 summarizes measures and estimated effect of grandparental child care on children's body weight status. Twelve studies focused on grandparents' roles as a main caregiver in the family, seven studies focused on grandparents' co-residence, two studies focused on grandparents' presence, one study focused on both grandparents' roles as a main caregiver in the family and grandparents' co-residence, and the remaining one focused on emotional and social support from grandparents.
Table 3. Measures and Estimated Effects of Grandparental Care on Children's Weight Outcomes
Study IDGrandparental roleObjective weight/height measureWeight outcomeEstimated effects on weight outcomeEstimated effects on diet and/or physical activity
1Grandmother as the child's primary caregiverYesBMI, overweight, obesityGrandmother being a child's primary caregiver was positively associated with childhood overweight/obesity (RR = 1.27; 95% CI: 1.03–1.52). 
2Children cared for by grandparentYesOverweight, obesityBeing cared by grandparents was positively associated with childhood overweight (RR = 1.18; 95% CI: 1.05–1.32). 
3Grandparents' co-residenceYesBMI, overweight, obesityBeing cared by grandparents in a migrant household was positively associated with younger children's (2–6 years of age) overweight (RR = 1.38, 95% CI: 0.92–1.79). 
4Grandparents' co-residenceYesBMI, overweight, obesityGrandparents' co-residence was positively associated with childhood overweight/obesity (RR = 1.53; 95% CI: 1.07–2.14).Grandparents' co-residence was negatively associated with childhood irregular mealtimes and irregular mealtimes associated with increased risks of being overweight/obese (OR = 2.03, 95% CI: 1.36–3.06).
5Grandparents' involvement in children's feeding and physical activityYesBMI, BMI z-score, overweight, obesity1. Grandparent involvement in caretaking was not associated with Cuban children's BMI z-score.
2. Grandparent involvement in caretaking was associated with lower BMI Z scores among children from other Hispanic origin groups.
1. Greater grandparent involvement positively was associated with negative eating.
2. There was no association between grandparent involvement and children's feeding and physical activity behaviors.
6Grandparents' involvement in child careYesOverweight, obesityGrandmothers as the primary child care are positively associated with children's overweight (RR = 1.14; 95% CI: 1.05–1.22). 
7Grandparents' co-residenceYesBMI, BMI z-score, waist circumference, waist-to-height ratio, skinfold thickness, overweight, obesityGrandparents' co-residence was positively associated with BMI z-scores (β = 0.62, 95% CI: 0.3–0.95). 
8Grandparents as the mainly caretakers and grandparents' co-residenceYesBMI, BMI z-score, overweight, obesityGrandparents as the main caretakers were positively associated with children's overweight/obese (RR = 1.62; 95% CI: 1.14–2.17).1. Grandparents as the mainly caretakers were positively associated with consumption of unhealthy snacks and sugar-added drinks.
2. Grandparents' co-residence was positively associated with achieving at least 60-m of moderate-to-vigorous-intensity physical activity daily for children.
9Grandmother's and grandfather's presenceYesWeight-for-age, height-for-age, and weight-for-height1. Grandmaternal presence was associated with significantly improved weight-for-height and weight-for-age during early infancy.
2. Grandmother's presence was positively associated with BMI z-scores during the 9–36-month period.
3. Grandmaternal presence was associated with higher weight-for-height over time.
Grandmother's co-residence is associated with substantially improved children's nutritional status at the age range of 9–36 months.
10Grandmother's and grandfather's presenceYesOverweight, obesityGrandparents' inappropriate perception, knowledge, and behavior contribute to childhood obesity.Grandparents as the main caregivers were positively associated with children's consumption of unhealthy snacks and sugar-added drinks (β = 2.13; 95% CI: 0.87, 3.40).
Grandparents tend to indulge, overfeed, and protect grandchildren in their care from physical chores, thus increasing their risk of obesity.
11Grandparents as the main daytime caregiversYesBMI, overweightBeing cared by grandparents was positively associated with children's mean BMI over time than those cared for by mothers (β = 0.39, 95% CI: 0.23–0.55).Being cared by grandparents had a higher prevalence of between-meal eating before dinner for children 6–12 years of age.
12Grandmother as the child's primary caregiverYesBMI, overweight, obesityRaising kids mainly by grandparents was associated with obesity in preschool children (RR = 1.43, 95% CI: 1.05–1.93). 
13Emotional and social support from grandparentsYesBMI z-scoreHaving emotional support from paternal grandparents was negatively associated with children's BMI z-score (β = −1.01, 95% CI: −1.76 to −0.26). 
14Grandparents' co-residenceYesBMI, overweight, obesityGrandparents' co-residence was positively associated with the likelihood of children's overweight and obesity at 5.5 years of age and older (RR = 1.46, 95% CI: 1.33–1.60). 
15Children cared for by grandparentNoOverweight, obesityLack of grandparents as the children's caregiver was interpreted as potential “protective” factors of obesity among migrant children.Grandparents were perceived to be associated with children's obesogenic behavior including unhealthy snacking.
16Grandmother as the child's primary caregiverYesOverweight, obesityBeing cared by grandparents was found to be more likely to develop overweight or obesity for 12-month-old infants (RR = 2.78, 95% CI: 1.76–4.09). 
17Grandparents' involvement in children's feedingYesBMI, BMI z-score, overweight, obesity1. Grandparents as main caregivers were associated with children's higher BMI z-scores (β = 0.66, 95% CI: 0.27–1.06).
2. Grandparents' indulgent feeding style was related to children's higher BMI z-scores (β = 0.54, 95% CI: 0.01–1.08).
 
18Grandparents' co-residenceYesOverweight, obesityGrandparents' co-residence was positively associated with childhood weight outcome (β = 1.430).Grandparents' co-residence affects a grandchild's weight outcome through changes in dietary patterns and physical activity.
19Children cared for by grandparentNoObesityGrandparents as the children's caregiver was associated with childhood obesity due to lacking necessary knowledge and skills, increasing food consumption, and decreasing activity levels.Grandparents' co-residence was associated with preventing adoption of healthy feeding practices, due to their personal experience or preference, especially regarding breastfeeding and weaning.
20Grandparents' involvement in children's feedingYesBMIThe presence of the grandmother was associated with childhood obesity.Grandmother feeding was positively associated with “modeling of eating behavior” scores and “restriction of unhealthy food behaviors” scores for children with BMI >85th percentile.
21Grandparents' co-residenceYesOverweight, obesityGrandparents' co-residence was positively associated with the incidence of overweight and obesity for preschool children (RR = 1.25, 95% CI: 1.15–1.35). 
22Children cared for by grandparentYesBMI percentile, overweight, obesityGrandparents as the children and adolescents' caretakers were positively associated with overweight than their counterparts without grandparent caretakers (RR = 1.41, 95% CI: 1.23–1.58).
No association was found between grandparental care and overweight in ages 2–5 and obesity in any age group.
 
23Grandparents' co-residenceYesBMI z-score, overweight, obesityGrandparent co-residence was associated with children's lower BMI z scores in the second grade (β = −0.048, 95% CI: −0.094 to −0.0013).Grandparent co-residence was associated with increased risk of irregular snack/food intake (RR = 1.38, 95% CI: 1.19–1.61).
Study ID 5, 9, 10, 15, 19, and 20 did not report the estimated effects and therefore, relevant cells are kept blank.
CI, confidence interval; RR, risk ratio.
Body weight status measures included BMI (n = 1), body weight (n = 1), weight for height (n = 1), BMI z-score (n = 5), and overweight and/or obesity status (n = 15). BMI-related measures were based on objectively measured height and weight (n = 21). Beside children's weight outcomes, 11 studies also reported the estimated effects of grandparental child care on children's diet and/or physical activity behaviors.
The estimated effects of grandparental child care on children's weight outcomes differed across the studies included in the review. In some studies, grandparents being a main caregiver in the family was found to be positively associated with childhood overweight and/or obesity,19,22–28 children's BMI z-scores,32 and children's mean BMI over time.33 Absence of grandparental child care was found to be potentially protective for migrant children's obesity risk.20 In addition, grandparents' co-residence was found to be positively associated with childhood overweight and/or obesity,34–36 children's BMI z-scores,37 and children's body weight.16
However, in other studies, Lau et al.28 reported a null finding between grandparental child care and childhood overweight among young children 2–5 years of age. Pulgarón et al.17 reported that grandparent's involvement in caregiving was not associated with BMI z-scores among Cuban elementary school children 6–10 years of age. They also found that grandparents' involvement in caregiving was inversely associated with BMI z-scores among children 6–10 years of age from certain Hispanic origin groups.17 Morita et al.38 reported grandparents' co-residence to be inversely associated with BMI z-scores among children 6–7 years of age. Lindberg et al.39 reported that receiving emotional support from paternal grandparents was inversely associated with BMI z-scores among children 4–6 years of age.
The estimated effects of grandparental child care on children's diet and/or physical activity were mixed. Some studies reported mostly obesity-prompting effects of grandparental child care. Grandparents' co-residence was inversely associated with the adoption of healthy feeding practices for infants.36 Children being cared by grandparents had a higher rate of between-meal eating before dinner.33 Grandparents being a main caregiver in the family increased unhealthy snacks and sugar-sweetened beverage consumption.19–21 Grandparents' co-residence was associated with decreased physical activity among children.16
In other studies, grandparental child care was either not associated with children's diet and/or physical activity or had a positive influence in the adoption of healthy diet and physical activity behaviors. Pulgarón et al.17 found no relationship between grandparental child care and children's diet or physical activity. In another study, grandparents' co-residence was associated with better nutritional status of young children 9–36 months of age29 and reduced frequency of irregular mealtimes among children.34 Moreover, grandparents' co-residence was positively associated with the likelihood of achieving at least 60 minutes of moderate-to-vigorous-intensity physical activity per day for children.19 Children cared by grandparents were more likely to be physically active.33

Meta-Analysis

Table 4 summarizes the modeling results from the meta-analysis. Data from 14 studies were used in the meta-analysis, 10 focusing on childhood overweight/obesity and the other 4 on children's BMI z-scores. A nonsignificant Begg's test suggested lack of publication bias for the impact of grandparental child care on childhood overweight/obesity (p = 0.13) and children's BMI z-score (p = 0.09). Results from the Egger's test did not identify publication bias for the impact of grandparental child care on childhood overweight/obesity (p = 0.07), but indicated the presence of publication bias for the impact of grandparental child care on children's BMI z-score (p = 0.04) (Fig. 2).
Figure 2. Funnel plots. (A) Funnel plot of grandparental care and childhood overweight. (B) Funnel plot of grandparental care and childhood BMI z-score.
Table 4. Results from Meta-Analysis and Publication Bias Tests
OutcomeStudy IDStudies included in meta-analysisI2 index, %Pooled estimate (coefficient for BMI z-score and RR of childhood overweight/obesity)Trim-and-fill estimate (coefficient for BMI z-score and RR of childhood overweight/obesity)ModelPublication bias test
Egger's testBegg's test
BMI z-score7, 11, 17, 23Formisano et al.37; Sata et al.33; Wei et al.32; Morita et al.3894.2Coefficient: 0.38 (0.01–0.75)Coefficient: 0.05 (−0.28 to 0.38)REp = 0.04p = 0.09
Childhood overweight/obesity1, 2, 3, 4, 6, 8, 12, 14, 21, 22Moschonis et al.22; Pearce et al.23; de Brauw and Mu24; Watanabe et al.34; Li et al.19; Tanskanen25; Zong et al.26; Ikeda et al.35; Ikeda and Nishi36; Lau et al.2862.5RR: 1.30 (1.21–1.40)RR: 1.20 (1.10–1.31)REp = 0.07p = 0.13
RE, random-effect model.
Compared with children not receiving grandparental child care, children with grandparental child care had a 30% increase in childhood overweight/obesity risk (95% confidence interval [CI] = 21–40; I2 = 62.5%; random-effect model). In addition, grandparental child care was associated with a 0.38 point increase in children's BMI z-scores (95% CI = 0.01–0.75, I2 index = 94.2%; random-effect model). However, the estimated increase in children's BMI z-scores was no longer statistically significant (β = 0.05; 95% CI = −0.28 to 0.38; random-effect model) after correcting for publication bias, using the nonparametric trim-and-fill procedure.30
In meta-regression, the effect of grandparental child care on children's weight outcomes did not differ across countries (i.e., Japan, China, and United Kingdom, vs. others, p = 0.08, 0.11, and 0.12, respectively) or by grandparents' roles (i.e., grandparents as the main caregiver vs. co-residence, p = 0.43).

Study Quality Assessment

Table 5 reports criterion-specific and global ratings from the study quality assessment. The included studies on average scored 8 out of 14, with a range from 5 to 11. All studies included in the review clearly stated the research question and objective, specified and defined the study population, had a participation rate above 50%, recruited participants from the same or similar populations during the same time period, and prespecified and uniformly applied inclusion and exclusion criteria to all potential participants. Most studies measured and statistically adjusted key potential confounding variables for their impact on the relationship between exposures and outcomes (n = 16), had an attrition rate less than 20% (n = 18), and implemented valid and reliable outcome measures (n = 21).
Table 5. Study Quality Assessment
Nine studies had a reasonably long follow-up period that was sufficient for changes in outcomes to be observed. Seven studies assessed the exposures more than once during the study period. In contrast, none of the studies measured exposures of interest (e.g., grandparents being a main caregiver in the family or grandparents' co-residence) before the outcomes, or had the outcome assessors blinded to the exposure status of the participants. Only two studies examined the different levels of exposure in relationship to the outcome, and only one study provided a sample size justification using power analysis.

Discussion

This study systematically reviewed the literature on the relationship between grandparental child care and childhood obesity. A total of 23 studies were identified from the keyword and reference search of 4 bibliographic databases. Meta-analysis found that grandparental child care was associated with an ∼30% increase in childhood overweight/obesity risk. However, grandparental child care was not associated with children's BMI z-scores after correcting for publication bias. In addition, findings on the relationship between grandparental child care and children's dietary and physical activity behaviors are mixed, with null, positive, and negative findings reported.
Qualitative studies across western and eastern cultures shed light on why there is an increased obesity risk with grandparental child care. Grandparents can influence children's body weight through mechanisms of perception and feeding practices.21,42,43 Some grandparents perceived heavier body weight in children as an indicator of good nutrition.42 As such, children were urged to eat larger meals and more frequent meals.21,44 Some grandparents were more likely to provide children with unhealthy food (e.g., sweets and fried food) as an expression of love and kindness.19,21 In some cultures, grandparents may be more likely to excuse children from doing household chores, an important form of physical activity.21
Although meta-analysis identified a positive association between grandparental child care and childhood overweight/obesity, grandparental child care was not associated with children's BMI z-scores. This is likely due to lack of statistical power given that only four studies included in this review analyzed children's BMI z-scores. It is also possible that the relationship between grandparental child care and childhood obesity is more complicated than a simple linear relationship. In addition, variation in study designs and measurements may have contributed to the seemingly inconsistent findings.
Furthermore, studies that evaluated the behavioral pathways linking grandparental child care to adiposity in children produced conflicting findings with positive, negative, and null findings. Substantial heterogeneities in study design and populations among the included studies may have contributed to the mixed findings.
We included a variety of study designs for a more inclusive review. Study populations covered a wide range of age groups from infants to adolescents from nine countries with diverging cultural beliefs, family practices, and economic development. Significant cross-cultural differences in parenting style, interpersonal dynamics, role satisfaction, and attachment to the grandchild among grandparents providing child care have been reported.45 Although country-specific differences regarding the relationship of grandparental child care and childhood obesity were not evident in meta-regression, it is possible that our analysis was underpowered to detect such differences.
Based on this systematic review, we identified a few major limitations of this review study and areas for future research.
First, all studies adopted an observational design, which is prone to self-selection and confounding bias. Family-based obesity interventions that incorporate grandparents are warranted to assess the causal impact of grandparental child care on children's weight outcomes.
Second, currently, studies tend to be scattered across countries and child age groups, and a “critical mass” of evidence is yet to form. A sizable cluster of studies focusing on age-specific groups within a country and/or cross-cultural comparisons is needed to uncover the more nuanced relationship between grandparental practices and child weight outcomes.
Third, the degree of grandparents' involvement in grandchildren's care and the specific duties they play are not specifically defined, measured, or described in most studies. It is perceivable that a grandparent who plans and cooks for family meals most of the time likely exerts more control over a child's diet behaviors than a grandparent whose primary responsibilities are to pick up the child from school. Better definition and measurement of grandparental child care roles and duties will further our understanding of the role that grandparents play in shaping children's behaviors and weight outcomes.
Moreover, the complex family dynamic and interactions between grandparents and parents in child care and how these interactions affect childhood obesity are understudied. Systematic and field-validated measures should be implemented to comprehensively document the multifaceted grandparental child care activities in relationship to children's health. The behavioral pathways linking grandparental child care to children's weight outcomes should be elucidated, which is expected to provide valuable information for the design of family-orientated childhood obesity interventions. The connection of other behaviors that influence energy balance, such as sleep and social media usage, to grandparental child care should also be examined.
The substantial heterogeneity in diet and physical activity measures prevented meta-analysis, so that we summarized corresponding findings narratively. Publication bias tends to exist on the relationship between grandpaternal care and children's BMI z-scores, which call for more studies and studies reporting null or negative findings.
In conclusion, this study systematically reviewed the scientific literature on the relationship between grandparental child care and childhood obesity. Meta-analysis found that grandparental child care was associated with a 30% increase in childhood overweight/obesity risk. However, we also found a lack of linear association between grandparental child care and children's BMI z-scores and mixed findings regarding the impact of grandparental child care on children's dietary and physical activity behaviors. Therefore, it is hard to draw a firm conclusion regarding the influence of grandparental child care on childhood obesity. 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.

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Published In

cover image Childhood Obesity
Childhood Obesity
Volume 16Issue Number 3April 2020
Pages: 141 - 153
PubMed: 31971822

History

Published in print: April 2020
Published online: 19 March 2020
Published ahead of print: 22 January 2020

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    Ruopeng An, PhD
    Brown School, Washington University, St. Louis, MO.
    Xiaoling Xiang, PhD
    School of Social Work, University of Michigan, Ann Arbor, MI.
    Na Xu, PhD
    Shanghai University, Shanghai, China.
    Jing Shen, PhD [email protected]
    Overseas Chinese College, Capital University of Economics and Business, Beijing, China.

    Notes

    Address correspondence to: Jing Shen, PhD, Overseas Chinese College, Capital University of Economics and Business, 121 Zhangjialukou, Huaxiang, Fengtai District, Beijing 100070, China [email protected]

    Author Disclosure Statement

    No competing financial interests exist.

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