Early Exposure to Cumulative Social Risk and Trajectories of Body Mass Index in Childhood.

BACKGROUND: Childhood social risk has been associated with increased risk of childhood obesity. However, little is known about early exposure of cumulative social risk on BMI percentile (BMIp) trajectories in early childhood.

METHODS: Public data from the Fragile Families and Child Wellbeing Study were analyzed (N = 3809). Maternal reports of experiences of multiple social risk factors were obtained at age 1 and 3 assessments of children. Two cumulative social risk scores were calculated by summing social factors assessed at age 1 and at age 3. Child BMIp was assessed at ages 3, 5, and 9. Linear mixed models were used to examine the effect of cumulative social risk on sex-specific BMIp trajectories.

RESULTS: Compared with girls experiencing low social risk at either age 1 or 3, girls experiencing high social risk (≥ 2 factors) at age 1 or 3 only had higher initial BMIp at age 3 [β0  = 5.70 (95% confidence interval, CI: 0.15-1.26) and 1.37 (95% CI: -2.25 to 4.99), respectively] and had nonsignificantly greater BMIp growth rate [β1  = 0.39 (95% CI: -0.86 to 1.63) and 0.32 (95% CI: -0.86 to 1.63)]. Girls experiencing high social risk at both ages had nonsignificantly but consistently lower BMIp [β1  = -1.24 (95% CI: -2.93 to 0.46)]. In addition, girls experiencing a sum of ≥4 risk factors at both ages had lower BMIp growth rate [β1  = -1.77 (95% CI: -3.39 to -0.15)] compared to girls experiencing no risk factor. No associations were observed among boys.

CONCLUSIONS: Early exposure to cumulative social risk may have long-term impact on BMIp trajectories among girls, depending on timing of exposure. Understanding the effect of cumulative social risk in different contexts, including sex, chronicity, and timing of exposure, may have practical implications for informing effective intervention to combat childhood obesity.