Maternal prenatal cortisol and the interaction of income and pre-pregnancy body mass index are independently associated with newborn cortisol.

While extensive research has supported the developmental programming hypothesis regarding contributions of prenatal psychosocial or nutritional adversity to offspring stress physiology, fewer studies consider both exposures together with maternal stress physiology. This study examined newborn cortisol output during a stressor as a function of maternal pre-pregnancy health status and nutritional history (pre-pregnancy body mass index [PPBMI]), economic resources (household income), and maternal cortisol awakening response (mCAR) in late pregnancy. Participants were 102 mother-infant pairs from an economically and racial/ethnically diverse sample. Offspring salivary cortisol response to a neurobehavioral exam was assessed at 1 month. Income and maternal PPBMI were positively associated with mCAR in late pregnancy. mCAR was positively related to 1-month newborn cortisol response. The interaction of income and PPBMI was positively associated with newborn cortisol output during an exam at 1-month. Mothers with the highest PPBMI and lowest income had offspring with higher cortisol responses than offspring of mothers with higher income and lower PPBMI. There was no evidence of indirect mediation effects of predictors (PPBMI, income, and interaction) on infant cortisol via mCAR. The differential effects of the interaction of PPBMI and income suggest that these exposures influence infant cortisol output in the context of one another, independent of maternal pregnancy cortisol.