Infant emotion regulation in the context of stress: Effects of heart rate variability and temperament.

Stressful events are inherently emotional. As a result, the ability to regulate emotions is critical in responding effectively to stressors. Differential abilities in the management of stress appear very early in life, compelling a need to better understand factors that may shape the capacity for emotion regulation (ER). Variations in both biologic and behavioural characteristics are thought to influence individual differences in ER development. We sought to determine the differential contributions of temperament and heart rate variability (HRV; an indicator of autonomic nervous system function) to infant resting state emotionality and emotional reactivity in response to a stressor at 6 months of age. Participants included 108 mother-infant dyads. Mothers completed a measure of infant temperament at 6 months postnatal. Mother and infant also participated in a standardized stressor (the Repeated Still Face Paradigm) at that time. Electrocardiographic data were acquired from the infant during a baseline resting state and throughout the stressor. Fast Fourier Transformation was used to analyse the high frequency (HF) domain of HRV, a measure of parasympathetic nervous system activity. Infant ER was measured via standardized coding of emotional distress behaviours from video-records at baseline and throughout the stressor. Severity of mothers' depressive symptoms was included as a covariate in analyses. Results of linear regression indicate that neither temperament nor HRV were associated significantly with an infant's emotional resting state, although a small effect size was found for the relationship between infant negative affectivity and greater emotional distress (ß = 0.23, p = 0.08) prior to the stressor. Higher HF-HRV (suggesting parasympathetic dominance) was related to greater emotional distress in response to the stressor (ß = 0.34, p = 0.009). This greater emotional reactivity may reflect a more robust capacity to mount an emotional response to the stressor when infants encounter it from a bedrock of parasympathetic activation. Findings may inform eventual markers for assessment of ER in infancy and areas for intervention to enhance infant management of emotions, especially during stressful events.

Exposure to antenatal corticosteroids and infant cortisol regulation.

Administration of antenatal corticosteroids (AC) is the standard of care during pregnancy for women who are at risk of early delivery. Evidence indicates that AC improve survival and reduce morbidity for preterm infants. However, research suggests that infants whose mothers receive AC have an altered hypothalamic-pituitary-axis (HPA) response to stressors in early life. Results are mixed regarding the nature of these effects, with studies showing both suppressed and augmented HPA activity. In addition, research is very limited beyond the 4th month of life. The purpose of this study was to determine if AC exposure was associated with infant cortisol levels in a resting state or in response to a stressor at 1, 6 and 12 months postnatal. We also evaluated the moderating role of preterm birth in this association. 181 women and their infants participated in the study. Women were recruited during the 3rd trimester of pregnancy; at this time, they completed the Perceived Stress Scale and provided 8 salivary samples over a 2-day period for cortisol assay. They provided these data again at 6 and 12 months postnatal. At 1, 6, and 12 months postnatal, salivary samples were collected from infants to examine their cortisol levels before and after participation in a 'stressor protocol'. Data were extracted from the medical record on AC exposure, gestational age, maternal obstetric risk, and neonatal morbidity. Mixed effects multilevel regression modeling was used to examine the aims. Infants whose mothers received AC had significantly lower resting state (B = -2.47, CI: -3.691, -0.0484) and post-stressor (B = -2.51, CI: -4.283, -0.4276) cortisol levels across the first year of life than infants whose mothers did not receive AC. There was no moderating effect of preterm birth on the relationship between AC exposure and cortisol. Results indicate a state of dampened HPA activation and cortisol hypo-arousal that persists across the first year of life among infants who were exposed to corticosteroids in utero. Further research is needed to examine mechanisms responsible for any alterations that occur during development of the fetal HPA axis, including epigenetic and biochemical factors that control hormonal secretion, negative feedback, and glucocorticoid receptor function throughout the HPA axis. Findings warrant careful consideration by obstetric clinicians of the benefits and risks of prescribing AC.

Effects of Antenatal Corticosteroids on Cortisol and Heart Rate Reactivity of Preterm Infants.

Administration of glucocorticoids (GCs) during pregnancy is an established practice for reducing morbidity and mortality of fetuses at risk of preterm delivery. However, preliminary research indicates that exposure to exogenous GCs in utero may be associated with suppressed hypothalamic-pituitary-adrenal axis activity. The aim of this study was to determine whether preterm neonates who are exposed to antenatal corticosteroids show evidence of a suppressed stress-response system during their first few weeks of life, in contrast to infants who are not exposed. The sample (51% female) included 57 neonates, with 74% exposed to steroids. Mean gestational ages (GAs) were 32.6 weeks for exposed and 34.7 weeks for nonexposed infants. Although neonates in the two groups differed in gender, birth weight, and morbidity, these factors were controlled for in data analyses. Infants' salivary cortisol and heart rate (HR) were measured before and after they received a standardized caregiving "stressor" while in the newborn intensive care unit. Infants exposed to GCs in utero had lower basal cortisol levels and higher HRs than their nonexposed peers. In contrast to infants who received no GCs, they also exhibited minimal HR or cortisol reactivity to the stressor. Findings suggest that preterm infants who were exposed to antenatal corticosteroids experience a suppressed response to stress. As preterm children develop, this dysregulation has numerous implications for later development of stress-related cardiovascular and mental health problems. Further research is needed to determine whether these postnatal effects of antenatal corticosteroids persist over time.

Factors Affecting Attachment in International Adoptees at 6 Months Post Adoption.

This pilot study examined the effect of five child and maternal factors on the attachment security of international adoptees at six months post adoption. Results from the sample of 22 adoptive mother-infant dyads showed that age at adoption, developmental status, length and quality of preadoption care, and maternal attachment representations were not significant predictors of child attachment status. The number of preadoption placements and the child's stress level did significantly predict attachment status, accounting for approximately 40% of the variance in attachment security. Number of preadoption placements uniquely contributed 14% of that variance (p=.007) while stress level uniquely contributed 12% (p=.01). Children who had fewer preadoption placements had higher attachment security; similarly, children who had lower stress levels had higher attachment security. Results suggest that consistency of preadoption care was more important than its length or quality. Further, the relationship between stress level and attachment security raises the possibility that a lower stress level functions as a protective factor for the developing attachment with the adoptive mother.

Attachment Behavior of Children Adopted Internationally at Six Months Post Adoption.

The purpose of this pilot study was to describe attachment behavior in children adopted internationally at 6 months post adoption. Twenty-two children and their adoptive mothers were observed at home for completion of an attachment measure. Mothers also completed a questionnaire on their child's preadoption care. Comparisons of children low and high in attachment security suggested that low secure children showed predominantly ambivalent attachment behavior or that they were still in the process of forming an attachment. Children having foster versus orphanage care prior to adoption differed in quality of preadoption care and in certain attachment behaviors, but not in overall attachment security.