This study examined infant response and recovery from a social challenge and parent responses. Behavioral and physiological responses were measured from forty-three 5- and 6-month-olds infants during a modified still-face procedure that used an additional still-face reunion sequence. Results confirm the hypothesis that infants of more responsive parents show more regulation than infants of less responsive parents. Infants of more responsive parents showed greater regulation of heart rate and negative affect during the final episode of the procedure than infants of less responsive parents. In addition, this procedure elicited a cortisol response (from .22 microg/dl to .31 microg/dl). Findings suggest important links between parent behavior and infant stress reactivity and regulation.

Data from animal models indicate that neonatal stress or pain can permanently alter subsequent behavioral and/or physiological reactivity to stressors. However, cumulative effects of pain related to acute procedures in the neonatal intensive care unit (NICU) on later stress and/or pain reactivity has received limited attention. The objective of this study is to examine relationships between prior neonatal pain exposure (number of skin breaking procedures), and subsequent stress and pain reactivity in preterm infants in the NICU. Eighty-seven preterm infants were studied at 32 (±1 weeks) postconceptional age (PCA). Infants who received analgesia or sedation in the 72 h prior to each study, or any postnatal dexamethasone, were excluded. Outcomes were infant responses to two different stressors studied on separate days in a repeated measures randomized crossover design: (1) plasma cortisol to stress of a fixed series of nursing procedures; (2) behavioral (Neonatal Facial Coding System; NFCS) and cardiac reactivity to pain of blood collection. Among infants born ≤ 28 weeks gestational age (GA), but not 29-32 weeks GA, higher cumulative neonatal procedural pain exposure was related to lower cortisol response to stress and to lower facial (but not autonomic) reactivity to pain, at 32 weeks PCA, independent of early illness severity and morphine exposure since birth. Repeated neonatal procedural pain exposure among neurodevelopmentally immature preterm infants was associated with down-regulation of the hypothalamic-pituitary-adrenal axis, which was not counteracted with morphine. Differential effects of early pain on development of behavioral, physiologic and hormonal systems warrant further investigation.

Objective-Little is known about the developmental trajectory of cortisol levels in preterm infants after hospital discharge.Study design-In a cohort of 225 infants (gestational age at birth <33 weeks) basal salivary cortisol levels were compared in infants born at extremely low gestational age (ELGA, 23-28 weeks), very low gestational age (VLGA, 29-32 weeks) and full-term (37-42 weeks), at 3, 6, 8 and 18 months corrected age (CA). Infants with major neurosensory and/or motor impairment were excluded.Results-At 3 months CA, salivary cortisol levels were lower in both preterm groups compared to the full-term infants (p = .003). Conversely, at 8 and 18 months CA, the ELGA infants had significantly higher basal cortisol levels than the VLGA and full-term infants (p = .016; p = .006 respectively).Conclusions-In ELGA infants, the shift from low basal cortisol levels at 3 months to significantly high levels at 8 and 18 months CA suggests long-term 're-setting' of endocrine stress systems. Multiple factors may contribute to these higher cortisol levels in the ELGA infants, including physiological immaturity at birth, cumulative stress related to multiple procedures and mechanical ventilation during lengthy hospitalization. Prolonged elevation of the cortisol "set-point" may have negative implications for neurodevelopment and later health. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.No author has any potential conflict of interest with this manuscript. Early environmental stress can permanently reorganize hormonal, physiological and behavioral systems, and increase vulnerability to illness and disorders later in life, a process referred to as "early programming." 1-6 For example, in rats, early adverse experiences such as prenatal stress, maternal separation or early deprivation result in increased stress hormone responses throughout the preweaning period and into adulthood. 2,3,6 Increased exposure to endogenous corticosteroids has adverse effects on cognitive abilities 7 and increases emotionality and anxiety-like behaviors in aversive situations. 8,9 NIH Public AccessIn general, sicker and smaller infants often show relatively low cortisol levels while in the neonatal intensive care unit (NICU). 10 We have recently shown a developmental shift whereby greater cumulative neonatal stress (higher number of skin-breaking procedures from birth to term) predicted lower cortisol levels in the NICU, 11 but elevated cortisol levels at 8 months corrected age (CA). 12 Little is known about the developmental trajectories of cortisol secretion in preterm infants after hospital dis...

Greater PAE was related to greater activation of stress response systems. Our findings suggest that PAE affects the development of infant stress systems and that these effects differ in boys and girls. This work supports the possibility that PAE is related to alterations in infant stress systems, which could underlie problems in cognitive and social-emotional functioning that are common among persons exposed prenatally to alcohol.

There is evidence that the developmental trajectory of cortisol secretion in preterm infants is altered, with elevated basal cortisol levels observed postnatally through at least 18 months corrected age (CA). This alteration is possibly due to neonatal pain-related stress. High cortisol levels might contribute to greater risk of impaired neurodevelopment. Since maternal factors are important for the regulation of infant stress responses, we investigated relationships between infant (neonatal painrelated stress, attention, cortisol) and maternal (stress, interactive behaviors) factors at age 8 months CA. We found that interactive maternal behaviors buffered the relationship between high neonatal pain-related stress exposure and poorer focused attention in mothers who self-reported low concurrent stress. Furthermore, in preterm infants exposed to high concurrent maternal stress and overwhelming interactive maternal behaviors, higher basal cortisol levels were associated with poor focused attention. Overall, these findings suggest that maternal factors can influence the cognitive resilience at 8 months of preterm infants exposed to early life stress.

SummaryCortisol plays an important role in learning and memory. An inverted-U shaped function has been proposed to account for the positive and negative effects of cortisol on cognitive performance and memory in adults, such that too little or too much impair but moderate amounts facilitate performance. Whether such relationships between cortisol and mental function apply to early infancy, when cortisol secretion, learning, and memory undergo rapid developmental changes, is unknown. We compared relationships between learning/memory and cortisol in preterm and full-term infants and examined whether a greater risk for adrenal insufficiency associated with prematurity produces differential cortisol-memory relationships. Learning in three-month old (corrected for gestational age) preterm and full-term infants was evaluated using a conjugate reinforcement mobile task. Memory was tested by repeating the same task 24 h later. Salivary cortisol samples were collected before and 20 min after the presentation of the mobile. We found that preterm infants had lower cortisol levels and smaller cortisol responses than full-term infants. This is consistent with relative adrenal insufficiency reported in the neonatal period. Infants who showed increased cortisol levels from 0 to 20 min on Day 1 had significantly better memory, regardless of prematurity, than infants who showed decreased cortisol levels.

Learning difficulties in preterm infants are thought to reflect impairment in arousal regulation. We examined relationships among gestational age, learning speed, and behavioral and physiological reactivity in 55 preterm and 49 full-term infants during baseline, contingency, and nonreinforcement phases of a conjugate mobile paradigm at 3 months corrected age. For all infants, negative affect, looking duration, and heart rate levels increased during contingency and nonreinforcement phases, whereas respiratory sinus arrhythmia (RSA, an index of parasympathetic activity) decreased and cortisol did not change. Learners showed greater RSA suppression and less negative affect than nonlearners. This pattern was particularly evident in the preterm group. Overall, preterm infants showed less learning, spent less time looking at the mobile, and had lower cortisol levels than full-term infants. Preterm infants also showed greater heart rate responses to contingency and dampened heart rate responses to nonreinforcement compared to full-term infants. Findings underscore differences in basal and reactivity measures in preterm compared to full-term infants and suggest that the capacity to regulate parasympathetic activity during a challenge enhances learning in preterm infants.More than 60 years ago, Shirley (1938Shirley ( , 1939 reported on a behavioral syndrome found in prematurely born children that included difficulties in motor function, sensory input, speech, social interactions, attention, learning, arousal, and emotion. Since that time, longitudinal studies of infants born prematurely with age-matched, full-term controls have demonstrated a greater incidence of behavioral, cognitive, and learning problems in infants born prematurely that persist into childhood (e.g., Anderson, Doyle, & Victorian Infant Collaborative Study Group, 2003;Grunau, Whitfield, & Davis, 2002;Pharoah, Stevenson, & West, 2003;Rose & Feldman, 1996;Taylor, Klein, Minich, & Hack, 2000) and late Copyright © Taylor & Francis Group, LLC Correspondence should be sent to Ruth E. Grunau, Centre for Community Child Health Research, F-6 4480 Oak Street, Vancouver, BC V6H 3V4 Canada. rgrunau@cw.bc.ca. Copyright of Infancy is the property of Lawrence Erlbaum Associates and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. NIH Public Access Author ManuscriptInfancy. Author manuscript; available in PMC 2010 August 16. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript adolescence (e.g., Grunau, Whitfield, & Fay, 2004;Hack et al., 2002;Saigal, Hoult, Streiner, Stoskopf, & Rosenbaum, 2000). Specifically, preterm infants are slower in the processing of novel (e.g., Gardner & Karmel, 1983;Landry, Leslie, Fletcher, & Francis, 1985;Millar & Weir, 1995;Rose, Feldman, Jankowski, & Caro, 2002;Rose, Feldman, McCarten, &Wolfson, 1988) and contingent stimulation (e.g., Gekos...

Understanding the relative and joint prioritization of age- and valence-related face characteristics in adults’ cortical face processing remains elusive because these two characteristics have not been manipulated in a single study of neural face processing. We used electroencephalography to investigate adults’ P1, N170, P2 and LPP responses to infant and adult faces with happy and sad facial expressions. Viewing infant vs adult faces was associated with significantly larger P1, N170, P2 and LPP responses, with hemisphere and/or participant gender moderating this effect in select cases. Sad faces were associated with significantly larger N170 responses than happy faces. Sad infant faces were associated with significantly larger N170 responses in the right hemisphere than all other combinations of face age and face valence characteristics. We discuss the relative and joint neural prioritization of infant face characteristics and negative facial affect, and their biological value as distinct caregiving and social cues.