Understanding pre- and perinatal factors that shape cortisol diurnal pattern and cortisol reactivity to a stressor is important because cortisol patterning is associated with a wide variety of physical and mental health outcomes (1). Few studies have examined potential pre- and perinatal predictors of cortisol patterning in children and their results have been inconsistent. The single study that examined maternal pregnancy weight gain found no association with the child’s cortisol level in a fasting plasma sample at age 8.5 years (2). No studies have examined maternal pre-pregnancy body mass index (BMI) as a potential predictor of cortisol patterning in the child. Of the studies examining the association of infant birth weight with cortisol patterning, some found an inverse association with hypothalamic-pituitary-adrenal (HPA) axis activity (3,4,5,6,7), others found a positive association (8,9), while others showed no association (10,11,12,13). The single study examining the association of infant gestational age with HPA axis functioning showed no association with saliva cortisol in adults (6). Interpretation of findings from these studies is limited by the fact that HPA axis outcomes were tested at widely varying ages, including late adulthood (5,6,7,8,10,12), childhood (3,4,11,13) and infancy (9). Interpretation is also limited due to varying cortisol measurement approaches, including serum (4,5,9,10,12,13), saliva (6,8,11) and urinary metabolites (3,7). In addition, most prior studies have been in European cohorts and there was broad variability in how cortisol patterning was characterized.
Thus, to our knowledge, no study has examined the independent associations of maternal pregnancy weight gain and pre-pregnancy BMI, infant’s birth weight and infant’s gestational age, with cortisol diurnal rhythm or cortisol reactivity to a stressor. In the present study, we tested the association of pre- and perinatal factors with salivary cortisol diurnal pattern and cortisol reactivity to a stressor in a racially and ethnically diverse sample of low-income United States preschoolers.