Association of parental body mass index (BMI) with child's health behaviors and child's BMI depend on child's age.

Background: Parent's and child's body mass index (BMI) are strongly associated, but their relationship varies by child's sex and age. Parental BMI reflects, among other factors, parents' behaviors and home environment, which influence their child's behaviors and weight. This study examined the indirect effect of parent's BMI on child's BMI via child health behaviors, conditional on child's sex and age.

Methods: Data from 2039 children and 1737 parents from eight cities of the U.S. involved in the Childhood Obesity Research Demonstration project tested the association between parental BMI and child's percentage of 95th BMI percentile (%BMIp95). A generalized structural equation modeling approach to path analysis was used to estimate and test simultaneously the associations among parental BMI and child's health behaviors and BMI across three age groups (preschool 2-4 yr., elementary 5-10 yr., and middle school 11-12 yr). Child's health behaviors were examined as mediators.

Results: Parental BMI was related to %BMIp95 across all age groups, and was strongest in 11-12 yr. children. Parental BMI was positively associated with boys' fruit and vegetable (FV) intake and girls' sugar-sweetened beverage (SSB) intake. Compared to 2-4 yr., older children had less FVs and physical activity, more screen time and SSB, and higher %BMIp95. Mediation effects were not significant.

Conclusions: Parental BMI was associated with child's %BMIp95 and some child behaviors, and this association was stronger in older children; older children also exhibited less healthy behaviors. Age- and sex-specific interventions that focus on age-related decreases in healthy behaviors and parental strategies for promoting healthy behaviors among at-risk children are needed to address this epidemic of childhood obesity.