Prenatal stress exposure and early childhood BMI: Exploring associations in a New Zealand context.

OBJECTIVES: The primary purpose of this study was to (i) examine associations between prenatal objective vulnerability and subjective stress, and (ii) investigate the relationships between prenatal vulnerability and subjective stress and early childhood BMI at 24- and 54- months of age after controlling for covariates.

METHODS: The Growing Up in New Zealand (GUiNZ) longitudinal study provided information on 5839 pregnant women and their children to assess the study objectives. Vulnerability, operationalized by nine objective-risk factors, and subjective stress, operationalized by the Perceived Stress Scale, were independently investigated. Hierarchical linear regression models were conducted to analyze the associations between both prenatal measures and childhood BMI at 24- and 54- months of age.

RESULTS: Correlations between subjective stress and objective vulnerability were low but significant (r = .28, P < .01). Exposure to one additional risk factor during pregnancy was significantly associated with a .11 increase in BMI z-score at 24-months (P < .01) and a .15 increase in BMI z-score at 54-months (P < .01), after controlling for covariates including maternal prepregnancy BMI. Subjective prenatal stress was not significantly associated with either child BMI outcome.

CONCLUSIONS: Vulnerability and subjective stress were minimally correlated in this sample. Vulnerability, but not subjective stress, was associated with childhood BMI at 24- and 54- months of age. This study informs our understanding of how risk exposures and stress responses early in life impacts offspring obesity risk, and it may help identify strategies that decrease early life predisposition to adult disease.