The effects of SES on infant and maternal salivary cortisol output

Children growing up in low-SES environments are exposed to more cumulative environmental stressors than children who do not live in poverty. Measuring salivary cortisol is one efficient way to quantify stress in humans, and cortisol output is commonly usedto examine the direct effects of low-SES environments. The purpose of the present study was to investigate the relationship between SES and salivary cortisol output for infants and mothers. We predicted that low-SES infants aged 6-12 months would display higher levels of diurnal cortisol output than high-SES infants. We also hypothesized that low-SES mothers would exhibit higher diurnal cortisol output compared to high-SES mothers. Our third hypothesis was that low-SES infants and mothers would exhibit poorer cortisol regulation over the course of the day compared to their high-SES counterparts. Finally, we hypothesized that maternal perceptions of chaos in the home would differ based on SES, and that these perceptions would be predictive of infant and maternal cortisol levels. We collected saliva samples from low and high SES infants aged 6-12 months and their mothers three times over the course of one day, while also administering a household chaos assessment. Both low-SES infant and maternal cortisol levels were marginally higher than high-SES infants and mothers over the course of one day. There were no SES-based differences in maternal perceptions of home chaos or in cortisol regulation patterns for infants or mothers. Because SES-based differences in cortisol output manifest this early in life, future research should focus on prenatal stress-reduction interventions.