Cortisol levels in relation to maternal interaction and child internalizing behavior in preterm and full-term children at 18 months corrected age

Skin-to-skin care (SSC) for term and preterm infants

Skin-to-skin care (SSC) is an important part of parent and infant care during the neonatal period and into infancy. SSC should be initiated immediately after birth and practiced as a standard of care in all settings, as well as in the home. There is strong evidence that SSC has a positive effect on breastfeeding and human milk feeding in both term and preterm infants, as well as on mortality, cardiopulmonary stability, and thermoregulation. SSC reduces pain and infant stress, enhances parent-infant bonding, has neurodevelopmental benefits, and has positive effects on parental mental health. The safety and feasibility of providing SSC has been established in term and preterm infants, and SSC is recommended as best practice for all infants. The benefits of SSC outweigh the risks in most situations, and despite challenges, care providers should implement procedures and accommodations to ensure that SSC occurs as a safe and positive experience for the parent, family, infant, and health care team. This statement includes all families as defined and determined by themselves, and recognizes that health communication, language, and terminology must be individualized to meet specific family needs by the health care team.

Les soins peau-à-peau chez les nourrissons à terme et prématurés

Les soins peau-à-peau (SPP) sont un aspect important des soins au parent et au nourrisson pendant la période néonatale et la première enfance. Ils doivent être entrepris immédiatement après la naissance et faire partie des soins standards dans tous les milieux, y compris à la maison. Selon de solides données probantes, les SPP ont un effet positif sur l'allaitement et l'alimentation par du lait humain, tant chez les nourrissons à terme que prématurés, de même que sur la mortalité, la stabilité cardiorespiratoire et la thermorégulation. Les SPP réduisent la douleur et le stress chez les nourrissons, accroissent l'attachement entre le parent et son nourrisson et ont des effets bénéfiques sur le neurodéveloppement de l'enfant ainsi que sur la santé mentale des parents. Le caractère sécuritaire et la faisabilité des SPP sont établis chez les nourrissons à terme et prématurés, et ces soins sont recommandés dans le cadre d'une pratique exemplaire auprès de tous les nourrissons. Les avantages des SPP sont supérieurs aux risques dans la plupart des situations, et malgré les défis qui y sont associés, les dispensateurs de soins devraient adopter des protocoles et prévoir des adaptations pour s'assurer que les SPP soient une expérience positive et sécuritaire pour le parent, la famille, le nourrisson et l'équipe soignante. Le présent document de principes s'adresse à toutes les familles, telles qu'elles se définissent et se déterminent elles-mêmes, et tiennent compte de l'importance de personnaliser la communication, le langage et la terminologie en matière de santé pour que l'équipe soignante réponde aux besoins particuliers de la famille.

A Preliminary Study of Correlates of Premature Birth and Their Influence on Cortisol Levels in Young Children

OBJECTIVE

The HPA-axis is programmed during early infancy, but a lot is unknown about the programming of the HPA-axis in prematurely born or small for gestational age (SGA) children. Therefore, the aim of this preliminary study was to investigate the influence of prematurity and variables associated with birth on cortisol levels in young children.

METHODS

Cortisol was measured in a cross-sectional design in 38 premature born participants (<37 weeks of gestation), aged between 3 - 9 years old. Correlates of prematurity (degree of prematurity and birth delivery route) were investigated in relationship with cortisol levels with regression analysis.

RESULTS

Corrected for sex, delivery by C-section was associated with lower cortisol levels in the children (ß = -.42, p = .028), with an explained variance of 34%.

CONCLUSION

Birth delivery route by C-section is associated with lowered (or flattened) cortisol levels in children born prematurely. This is clinically relevant and might have important implications, because an HPA-axis disturbance might lead to developmental problems later on in life. However, future research is necessary to investigate the underlying indications for performing a C-section, which will help to understand factors that influence the HPA-axis development in children born prematurely.

Alleviating Neonatal Intensive Care Unit Stress: A Chinese Medicine Approach in Neonatal Rats

Background

Premature infants are exposed to numerous stressors in neonatal intensive care unit (NICU) during a crucial period for brain development; this period exerts long-term influences on cognitive and behavioral development.

Aims

To evaluate the effect of NICU-related stress on neonatal rat pups and explore the effect of Chinese medicine treatment (CMT).

Methods

Sixty male rat pups were randomly assigned to three groups: the control group, the NICU group (NICU-related stress), and the CMT group (NICU-related stress plus CMT). All stressors and interventions were administered from 0 to 7 days after birth. Body weight, serum corticosterone levels, and behavior in the open field (OF) test, elevated plus maze (EPM) test, sucrose preference test, and Morris water maze (MWM) test were recorded, and blood samples were collected at five different time points (T0, T1, T2, T3, and T4).

Results

The body weights of rats in the CMT and control groups were heavier than those in the NICU group in both early life and adulthood (P < 0.05). Serum corticosterone levels significantly differed with time (except T0 vs. T1 and T3 vs. T4) but did not significantly differ among the three groups (F = 0.441, P = 0.894). Regardless of age, spatial memory and anxiety-like and depression-like behavior did not differ among the three groups.

Conclusion

NICU-related stress exerted a long-term effect on rat growth and development but did not affect spatial memory, anxiety-like behavior, depression-like behavior, or serum corticosterone levels. CMT alleviated the impact of NICU-related stress on rats and promoted the growth and development of neonatal rats.

Relationships between cortisol levels across early childhood and processing speed at age 4.5 years in children born very preterm

Children born very low gestational age (VLGA, 29-32 weeks gestational age [GA]) display slower processing speed and altered hypothalamic pituitary adrenal (HPA) axis function, with greater effects in those born extremely low gestational age (ELGA; 24-28 weeks GA). We investigated trajectories of HPA axis activity as indexed by cortisol output and patterns across cognitive assessment at ages 1.5, 3 and 4.5 years, comparing children born ELGA and VLGA and associations with 4.5-year processing speed. In a prospective longitudinal cohort study, infants born very preterm (<33 weeks gestation) returned for developmental assessment at ages 1.5, 3, and 4.5 years. At each age, children completed standardized cognitive testing and saliva samples collected before (Pretest), during (During) and after (End) challenging cognitive tasks were assayed for cortisol. For the total group (n = 188), cortisol area under the curve with respect to ground (AUCg) decreased, while cortisol reactivity to challenge (Pre-test to During) increased from 1.5 to 3 years, remaining stable to 4.5 years. This longitudinal pattern was related to higher Processing Speed (WPPSI-IV) scores at 4.5 years. Children born ELGA displayed higher AUCg than VLGA, particularly at age 3, driven by higher Pre-test cortisol levels. Overall, relative to those born VLGA, children born ELGA displayed greater cortisol responsivity to cognitive challenge. A higher setpoint of cortisol levels at age 3-years in children born ELGA may reflect altered HPA axis regulation more broadly and may contribute to difficulties with information processing in this population, critical for academic and social success.

Effect of non-pharmacological interventions on pain in preterm infants in the neonatal intensive care unit: a network meta-analysis of randomized controlled trials

OBJECTIVE

To evaluate the effectiveness of different non-pharmacological interventions for pain management in preterm infants and provide high-quality clinical evidence.

METHODS

Randomized controlled trials (RCTs) of various non-pharmacological interventions for pain management in preterm infants were searched from PubMed, Web of Science, Embase, and the Cochrane Library from 2000 to the present (updated March 2023). The primary outcome was pain score reported as standardized mean difference (SMD). The secondary outcomes were oxygen saturation and heart rate reported as the same form.

RESULTS

Thirty five RCTs of 2134 preterm infants were included in the meta-analysis, involving 6 interventions: olfactory stimulation, combined oral sucrose and non-nutritive sucking (OS + NNS), facilitated tucking, auditory intervention, tactile relief, and mixed intervention. Based on moderate-quality evidence, OS + NNS (OR: 3.92, 95% CI: 1.72, 6.15, SUCRA score: 0.73), facilitated tucking (OR: 2.51, 95% CI: 1.15, 3.90, SUCRA score: 0.29), auditory intervention (OR: 2.48, 95% CI: 0.91, 4.10, SUCRA score: 0.27), olfactory stimulation (OR: 1.80, 95% CI: 0.51, 3.14, SUCRA score: 0.25), and mixed intervention (OR: 2.26, 95% CI: 0.10, 4.38, SUCRA score: 0.14) were all superior to the control group for pain relief. For oxygen saturation, facilitated tucking (OR: 1.94, 95% CI: 0.66, 3.35, SUCRA score: 0.64) and auditory intervention (OR: 1.04, 95% CI: 0.22, 2.04, SUCRA score: 0.36) were superior to the control. For heart rate, none of the comparisons between the various interventions were statistically significant.

CONCLUSION

This study showed that there are notable variations in the effectiveness of different non-pharmacological interventions in terms of pain scores and oxygen saturation. However, there was no evidence of any improvement in heart rate.

Cortisol levels are related to neonatal pain exposure in children born very preterm at age 18 months in two independent cohorts

Exposure to pain-related stress from frequent invasive procedures in the neonatal intensive care unit (NICU) has been associated with altered physiological stress regulation, neurodevelopment, and behavior in children born very preterm (≤32 weeks gestation). Previously, in a cohort born 2003-2006 (Cohort 1), we found that, at 18 months corrected age (CA), children born extremely low gestational age (ELGA; 24-28 weeks) and very low gestational age (VLGA; 29-32 weeks), had higher pre-test cortisol levels and a different pattern of cortisol output across a developmental assessment involving cognitive challenge compared to children born full-term (FT; 39-41 weeks). Also, greater neonatal pain-related stress exposure among the preterm children was related to higher pre-test cortisol levels. Given the adverse long-term effects of neonatal pain in preterm infants and the ensuing rise in clinical concerns to appropriately manage pain in the NICU in recent years, we aimed to examine whether our findings from Cohort 1 would still be evident in an independent cohort (Cohort 2) born 2006-2011 and recruited from the same tertiary NICU in Vancouver, Canada. We also compared the cortisol patterns, clinical and socio-demographic factors, and their interrelationships between the two cohorts. In Cohort 2, our findings using multi-level modeling support and extend our earlier findings in Cohort 1, demonstrating that children born ELGA display higher pre-test cortisol levels than FT. As well, greater cortisol output across assessment was related to more anxiety/depressive behaviors in children born VLGA. Importantly, children born ELGA were exposed to less neonatal pain/stress, mechanical ventilation, and morphine in Cohort 2 than Cohort 1. In both cohorts, however, cortisol levels and patterns were related to neonatal pain/stress and clinical factors (days on mechanical ventilation, overall morphine exposure). Despite less exposure to pain/stress and adverse clinical factors in Cohort 2 compared to Cohort 1, cortisol levels and patterns across cognitive challenge in preterm children at 18-month CA were consistent across the two independent cohorts. These findings highlight that, despite improvements to neonatal care, children born extremely preterm continue to display altered HPA axis activity, which is associated with their poorer neurodevelopmental and behavioral outcomes.

Developmental Cascades Link Maternal-Newborn Skin-to-Skin Contact with Young Adults' Psychological Symptoms, Oxytocin, and Immunity; Charting Mechanisms of Developmental Continuity from Birth to Adulthood

Premature birth disrupts the continuity of maternal-newborn bodily contact, which underpins the development of physiological and behavioral support systems. Utilizing a unique cohort of mother-preterm dyads who received skin-to-skin contact (Kangaroo Care, KC) versus controls, and following them to adulthood, we examined how a touch-based neonatal intervention impacts three adult outcomes; anxiety/depressive symptoms, oxytocin, and secretory immunoglobulin A (s-IgA), a biomarker of the immune system. Consistent with dynamic systems' theory, we found that links from KC to adult outcomes were indirect, mediated by its effects on maternal mood, child attention and executive functions, and mother-child synchrony across development. These improvements shaped adult outcomes via three mechanisms; (a) "sensitive periods", where the infancy improvement directly links with an outcome, for instance, infant attention linked with higher oxytocin and lower s-IgA; (b) "step-by-step continuity", where the infancy improvement triggers iterative changes across development, gradually shaping an outcome; for instance, mother-infant synchrony was stable across development and predicted lower anxiety/depressive symptoms; and (c) "inclusive mutual-influences", describing cross-time associations between maternal, child, and dyadic factors; for instance, from maternal mood to child executive functions and back. Findings highlight the long-term impact of a birth intervention across development and provide valuable insights on the mechanisms of "developmental continuity", among the key topics in developmental research.

Cortisol reactivity and negative affect among preterm infants at 12 months during a mother-infant interaction task

The purpose of this study was to investigate correlates of preterm (PT) infant's cortisol reactivity and the association to infant negative affect, during a mother-infant interaction procedure. Participants included 48 infants born prematurely (gestational age < 37 weeks) and their mothers, assessed when infants were 12 months old corrected for prematurity. The examined variables comprised both neonatal and environmental dimensions including maternal interactive behavior. Infant negative affect and maternal interactive behavior were assessed with a standardized mother-infant interaction task. A baseline infant saliva sample was collected before the interaction began, and a second sample after the interaction episodes ended. Results revealed that decrease of infant's cortisol concentration was significantly associated with the exposure to more sensitive, and less intrusive maternal behaviors. However, once controlled for neonatal risk, family SES and maternal psychological distress, the associations were rendered non-significant. Although the association between cortisol reactivity and negative affect trended toward significance, maternal intrusiveness was the only significant predictor of observed infant negative affect. Findings suggest the importance of primary relational experiences on PT infants' early regulatory competencies.

Cortisol awakening response and developmental outcomes at 6-7 years in children born extremely preterm

BACKGROUND

Extremely preterm (EPT) birth has been related to dysregulation of stress responses and behavioral/learning problems at school age. Early adverse experiences can blunt HPA axis reactivity. We hypothesized that an attenuated cortisol awakening response would be associated with developmental and behavioral problems at school age in EPT children.

METHODS

This secondary analysis of a sub-cohort of the SUPPORT study included children born between 24 and 27 weeks, evaluated at 6-7 years with a neurodevelopmental battery and cortisol measures. Differences were tested between EPT and a term-born group. Relationships of cortisol awakening response to test scores were analyzed.

RESULTS

Cortisol was measured in 110 EPT and 29 term-born 6-7 year olds. Unadjusted WISC-IV and NEPSY-II scores were significantly worse among EPT children only. Conners Parent Rating Scale behavior scores were significantly worse among EPT children. After adjusting for covariates, blunted cortisol awakening responses were found to be associated with poorer scores on memory tests and greater problems with inattention for the EPT group (p < 0.05) only.

CONCLUSIONS

Among children born EPT, we identified an association of blunted cortisol awakening response with memory and inattention problems. This may have implications related to stress reactivity and its relationship to learning problems in children born EPT.

CLINICALTRIALS

GOV ID

Extended Follow-up at School Age for the SUPPORT Neuroimaging and Neurodevelopmental Outcomes (NEURO) Cohort: NCT00233324.

IMPACT

In children born EPT, stress reactivity may have a relationship to learning problems. Cortisol awakening response should be a component for follow-up in EPT born children. Components of executive function, such as memory and attention, are related to stress reactivity.

Lower Maternal Chronic Physiological Stress and Better Child Behavior at 18 Months: Follow-Up of a Cluster Randomized Trial of Neonatal Intensive Care Unit Family Integrated Care

OBJECTIVE

To assess whether Family Integrated Care (FICare) in the neonatal intensive care unit improves maternal chronic physiological stress and child behavior at 18 months of corrected age for infants born preterm.

STUDY DESIGN

Follow-up of a multicenter, prospective cluster-randomized controlled trial comparing FICare and standard care of children born at <33 weeks of gestation and parents, stratified by tertiary neonatal intensive care units, across Canada. Primary outcomes at 18 months of corrected age were maternal stress hormones (cortisol, ie, hair cumulative cortisol [HCC], dehydroepiandrosterone [DHEA]) assayed from hair samples. Secondary outcomes included maternal reports of parenting stress, child behaviors (Internalizing, Externalizing, Dysregulation), and observer-rated caregiving behaviors. Outcomes were analyzed using multilevel modeling.

RESULTS

We included 126 mother-child dyads from 12 sites (6 FICare sites, n = 83; 6 standard care sites, n = 43). FICare intervention significantly lowered maternal physiological stress as indicated by HCC (B = -0.22 [-0.41, -0.04]) and cortisol/DHEA ratio (B = -0.25 [-0.48, -0.02]), but not DHEA (B = 0.01 [-0.11, 0.14]). Enrollment in FICare led to lower child Internalizing (B = -0.93 [-2.33, 0.02]) and Externalizing behavior T scores (B = -0.91 [-2.25, -0.01]) via improvements to maternal HCC (mediation). FICare buffered the negative effects of high maternal HCC on child Dysregulation T scores (B = -11.40 [-23.01, 0.21]; moderation). For mothers reporting high parenting stress at 18 months, FICare was related to lower Dysregulation T scores via maternal HCC; moderated mediation = -0.17 (-0.41, -0.01).

CONCLUSIONS

FICare has long-term beneficial effects for mother and child, attenuating maternal chronic physiological stress, and improving child behavior in toddlerhood.

CLINICAL TRIAL REGISTRATION

NCT01852695.

Understanding early-life pain and its effects on adult human and animal emotionality: Translational lessons from rodent and zebrafish models

Critical for organismal survival, pain evokes strong physiological and behavioral responses in various sentient species. Clinical and preclinical (animal) studies markedly increase our understanding of biological consequences of developmental (early-life) adversity, as well as acute and chronic pain. However, the long-term effects of early-life pain exposure on human and animal emotional responses remain poorly understood. Here, we discuss experimental models of nociception in rodents and zebrafish, and summarize mounting evidence of the role of early-life pain in shaping emotional traits later in life. We also call for further development of animal models to probe the impact of early-life pain exposure on behavioral traits, brain disorders and novel therapeutic treatments.

The impact of Nonpharmacological Interventions on Cortisol During Heel Lance Procedures on Preterm Infants: A Meta-Analysis Of RCTs

BACKGROUND

Current research suggests a need to implement environmental, behavioral, and even nutritional interventions, with the objective of improving the comfort and stability of preterm newborn infants, as well as reducing their stress and pain levels. Several studies have used the salivary reactivity of cortisol to assess stress or pain in preterm infants. The aim of this study was to analyze the results of published randomized controlled trials that tested the effects of nonpharmacological interventions on cortisol as a treatment for heel lance pain/stress in preterm infants.

METHODS

Published randomized controlled trials (RCTs) were searched in PubMed, Embase, CINHAL, Web of Science Cochrane Library, and Cochrane Database of Systematic Reviews, and six studies met the eligibility criteria. The quality of the included studies was appraised using Cochrane's Collaboration tool.

RESULTS

The meta-analysis showed that non-pharmacological interventions were associated with a reduction in levels of salivary cortisol in comparison with other interventions and controls, with fixed effect mean differences of -0.11, and with a 95% C.I. of -0.28 to -0.05. Prone-nest position, breast milk odor, kangaroo care, and twins co-bedding led to a decrease in cortisol levels in saliva.

CONCLUSION

Future studies should be performed on nonpainful interventions in order to gain more knowledge about the regulation of cortisol in saliva in preterm infants with involving control group and larger sample sizes.

Effect of combined pharmacological, behavioral, and physical interventions for procedural pain on salivary cortisol and neurobehavioral development in preterm infants: a randomized controlled trial

Repeated procedural pain may lead to increased secretion of cortisol and future neurobehavioral development disorders in preterm infants. Changes in the cortisol level may mediate the effect of neonatal repetitive procedural pain on altered childhood neurobehavioral development in preterm infants. However, few studies have investigated the effect of combined pharmacological, behavioral, and physical interventions over repeated painful procedures on pain response, cortisol level, and neurobehavioral development. This study examined (1) the efficacy and safety of sucrose combined with massage, music, non-nutritive sucking, and gentle human touch to treat preterm infants with repeated procedural pain; (2) the cortisol level at discharge from the neonatal intensive care unit (NICU); (3) neurobehavioral development at 40 weeks' corrected gestational age; and (4) the potential mediating effect of the cortisol level in the combined interventions on neurobehavioral development. Stable preterm infants (n = 76) were randomized to receive routine care or combined interventions across repeated painful procedures throughout their NICU stay. The Premature Infant Pain Profile scores in the early, middle, and late periods of the NICU stay were measured, as were the basal salivary cortisol level at admission and discharge, the Neonatal Behavioral Neurological Assessment score at 40 weeks' corrected gestational age, and the incidence of adverse effects during the study period. Our findings indicated that the combined interventions remained efficacious and safe for reducing repeated procedural pain, decreased the cortisol level at discharge, and promoted early neurobehavioral development in preterm infants. This effect may have been mediated through decreased cortisol levels and reduced repeated procedural pain.

Premature Birth and Developmental Programming: Mechanisms of Resilience and Vulnerability

The third trimester of pregnancy represents a sensitive phase for infant brain plasticity when a series of fast-developing cellular events (synaptogenesis, neuronal migration, and myelination) regulates the development of neural circuits. Throughout this dynamic period of growth and development, the human brain is susceptible to stress. Preterm infants are born with an immature brain and are, while admitted to the neonatal intensive care unit, precociously exposed to stressful procedures. Postnatal stress may contribute to altered programming of the brain, including key systems such as the hypothalamic-pituitary-adrenal axis and the autonomic nervous system. These neurobiological systems are promising markers for the etiology of several affective and social psychopathologies. As preterm birth interferes with early development of stress-regulatory systems, early interventions might strengthen resilience factors and might help reduce the detrimental effects of chronic stress exposure. Here we will review the impact of stress following premature birth on the programming of neurobiological systems and discuss possible stress-related neural circuits and pathways involved in resilience and vulnerability. Finally, we discuss opportunities for early intervention and future studies.

Sensory processing and cortisol at age 4 years: Procedural pain-related stress in children born very preterm

Children born preterm display altered sensory processing, which may manifest as hyper- and/or hypo-sensitivity to sensory information. In this vulnerable population, exposure to neonatal pain-related stress is associated with altered stress regulation, as indexed by alterations in cortisol levels. It is unknown whether sensory processing behaviors are also affected by early life adversity, and whether dysregulated cortisol is related to sensory processing problems in preterm children. We examined relationships between neonatal pain-related stress, sensory processing profiles and cortisol levels at age 4 years, and whether pathways were sex-specific. In a longitudinal prospective cohort study, N = 146 infants born 24-32 weeks gestational age were recruited from BC Women's Hospital, Vancouver, BC, Canada; neonatal factors were collected from daily chart review. At age 4 years, saliva to assay cortisol was collected three times across cognitive assessment (pre-test, during, end) and parents completed the Short Sensory Profile questionnaire. Using generalized linear modeling, independent of other neonatal factors, higher number of invasive procedures (pain/stress) was associated with more sensory processing problems (total, hypo- and hyper-sensitivity) for girls only. After accounting for neonatal factors, greater cortisol output across the assessment was associated with more total sensory processing problems in girls only, and hypersensitivity to sensory input in both boys and girls. Findings suggest that in children born very preterm, how a child responds to sensory input and cortisol reactivity to stress are related but may have different precursors. Girls may be somewhat more susceptible to neonatal pain-related stress exposure in relation to sensory processing at preschool age.

Personal perspectives: Infant pain—A multidisciplinary journey

Understanding of infant pain has been transformed in the past 30 years. From assumptions that newborns were insensitive to pain, fundamental work established not only the infants perceive pain, but also there are critical windows in which pain can have long‐lasting consequences. My multidisciplinary work revealed that repetitive pain exposure during the late 2nd and 3rd trimesters of fetal life “ex‐utero” in infants born very preterm is related to long‐term adverse associations with altered brain development, programming of stress systems, and thereby neurodevelopment. Here, influences will be described, discovery research summarized, and evidence of biological pathways proposed.

Hair cortisol concentration mediates the association between parent and child psychopathology

Parent and child mental health are strongly associated and this association may be transmitted via disruption to the hypothalamic-pituitary-adrenal axis in children. This study examined the potential mediating role of hair cortisol concentration (HCC) in the association between parent psychopathology and child mental disorder. Data come from 100 children diagnosed with a mental disorder [major depression (66 %), generalized anxiety (58 %), attention-deficit hyperactivity (33 %), oppositional defiant (35 %)] and their parents. Parent psychopathology was measured using the Center for Epidemiological Studies Depression Scale and State-Trait Anxiety Inventory. Child mental disorder was measured using the Mini International Neuropsychiatric Interview and hair samples were assayed using high-sensitivity ELISA for cortisol extraction. Sex-specific path models were specified to estimate mediating effects (αβ). Children were, on average, 14.4 (SD 2.3) years of age and 70 % were girls. Adjusting for child age, parent sex, and family income, HCC mediated the association between symptoms of parent psychopathology and major depression and attention-deficit hyperactivity in all children (αβ ranging -0.07 to 0.19; 38-46 % effect mediated). Mediating effects for generalized anxiety and opposition defiant were evident for boys only (αβ ranging -0.26 to 0.14; 31-38 % effect mediated). Evidence suggests HCC partially mediates the association between parent psychopathology and child mental disorder, and for generalized anxiety and oppositional defiant, this effect is specific to boys. Family inventions to reduce child stress may be effective in buffering the consequences of parent psychopathology. Further research that considers sex effects is needed to clarify how HCC conditions risk for mental disorder in children.

Temperament moderated by neonatal factors predicted behavioral problems in childhood: A prospective longitudinal study

OBJECTIVE

The present study aimed to examine the predictor effects of neonatal, sociodemographic characteristics, and temperament assessed at 18-36 months of age on behavioral problems in 4- to 5-year-old children born preterm.

METHODS

The sample comprised 70 children born preterm. The amount and the intensity of stress procedures during a stay in the neonatal intensive care unit were evaluated using the Neonatal Infant Stressor Scale. Temperament was assessed using the Early Childhood Behavior Questionnaire, and behavioral problems were assessed using the Child Behavior Checklist 1^1/2-5. Multiple linear regression analysis was performed.

RESULTS

Total behavioral problems were predicted by a child temperament of more negative affectivity and less effortful control, moderated by gestational age. Internalizing behavioral problems was predicted by more negative affectivity and less effortful control moderated by male sex and associated with lower gestational age. Externalizing behavior problems was predicted by less effortful control.

CONCLUSIONS

The main findings of the present study showed that the high immaturity at the birth of preterm infants, associated with temperament traits of more negative affectivity and less effortful control, increase the risk for future behavioral problems.

Maternal Postpartum Depression Increases Vulnerability for Toddler Behavior Problems through Infant Cortisol Reactivity

The current study examined the role of hypothalamic-pituitary-adrenal reactivity (a physiological indicator of stress) in early infancy as a mediator of the relationship between maternal postpartum depression and toddler behavior problems. Participants were 137 at-risk mothers and their children participating in a longitudinal study of intergenerational transmission of risk. Mothers' depression was measured five times during the infants' first 18 months. Infant cortisol was collected during a social stressor (the still-face paradigm) when infants were 6 months old, and mothers reported on toddlers' internalizing and externalizing symptoms at 18 months. Among this sample of high-risk mother-infant dyads, early postpartum depression predicted atypical infant cortisol reactivity at 6 months, which mediated the effect of maternal depression on increased toddler behavior problems. Clinical implications are discussed.

Maternal depression alters stress and immune biomarkers in mother and child

BACKGROUND

Exposure to maternal depression bears long-term negative consequences for children's well-being. Yet, no study has tested the joint contribution of maternal and child's hypothalamic pituitary axis and immune systems in mediating the effects of maternal depression on child psychopathology.

METHODS

We followed a birth cohort over-represented for maternal depression from birth to 10 years (N = 125). At 10 years, mother and child's cortisol (CT) and secretory immunoglobulin A (s-IgA), biomarkers of the stress and immune systems, were assayed, mother-child interaction observed, mothers and children underwent psychiatric diagnosis, and children's externalizing and internalizing symptoms reported.

RESULTS

Depressed mothers had higher CT and s-IgA levels and displayed more negative parenting, characterized by negative affect, intrusion, and criticism. Children of depressed mothers exhibited more Axis-I disorders, higher s-IgA levels, and greater social withdrawal. Structural equation modeling charted four paths by which maternal depression impacted child externalizing and internalizing symptoms: (a) increasing maternal CT, which linked with higher child CT and behavior problems; (b) augmenting maternal and child's immune response, which were associated with child symptoms; (c) enhancing negative parenting that predicted child social withdrawal and symptoms; and (d), via a combined endocrine-immune pathway suppressing symptom formation.

CONCLUSIONS

Our findings, the first to test stress and immune biomarkers in depressed mothers and their children in relation to social behavior, describe mechanisms of endocrine synchrony in shaping children's stress response and immunity, advocate the need to follow the long-term effects of maternal depression on children's health throughout life, and highlight maternal depression as an important public health concern.

From early stress to 12-month development in very preterm infants: Preliminary findings on epigenetic mechanisms and brain growth

Very preterm (VPT) infants admitted to Neonatal Intensive Care Unit (NICU) are at risk for altered brain growth and less-than-optimal socio-emotional development. Recent research suggests that early NICU-related stress contributes to socio-emotional impairments in VPT infants at 3 months through epigenetic regulation (i.e., DNA methylation) of the serotonin transporter gene (SLC6A4). In the present longitudinal study we assessed: (a) the effects of NICU-related stress and SLC6A4 methylation variations from birth to discharge on brain development at term equivalent age (TEA); (b) the association between brain volume at TEA and socio-emotional development (i.e., Personal-Social scale of Griffith Mental Development Scales, GMDS) at 12 months corrected age (CA). Twenty-four infants had complete data at 12-month-age. SLC6A4 methylation was measured at a specific CpG previously associated with NICU-related stress and socio-emotional stress. Findings confirmed that higher NICU-related stress associated with greater increase of SLC6A4 methylation at NICU discharge. Moreover, higher SLC6A4 discharge methylation was associated with reduced anterior temporal lobe (ATL) volume at TEA, which in turn was significantly associated with less-than-optimal GMDS Personal-Social scale score at 12 months CA. The reduced ATL volume at TEA mediated the pathway linking stress-related increase in SLC6A4 methylation at NICU discharge and socio-emotional development at 12 months CA. These findings suggest that early adversity-related epigenetic changes might contribute to the long-lasting programming of socio-emotional development in VPT infants through epigenetic regulation and structural modifications of the developing brain.

Salivary cortisol reactivity in preschoolers is associated with hair cortisol and behavioral problems

The interplay between children's cortisol reactivity to challenge and cumulative cortisol exposure is not well understood. Examining the role of cortisol reactivity in early childhood may elucidate biological mechanisms that contribute to children's chronic physiological stress and behavioral dysregulation. In a sample of 65 preschool-aged children, we examined the relation between children's salivary cortisol reactivity to challenging tasks and their hair cortisol concentration (HCC). While both are biomarkers of the hypothalamic-pituitary-adrenal (HPA) axis, salivary cortisol reactivity reflects an acute cortisol response to a stressor and HCC reflects cumulative cortisol exposure. In addition, we examined the relations of these stress biomarkers with internalizing and externalizing problems. Salivary cortisol reactivity was associated with higher HCC and with increased externalizing behaviors. Child HCC also was positively correlated with parent HCC. Results highlight the contributions of salivary cortisol reactivity to children's cumulative cortisol exposure, which may add to their biological risk for health problems later. The observed association between externalizing problems and salivary cortisol reactivity indicates concordances between dysregulated behavioral reactions and dysregulated cortisol responses to challenges. The finding that salivary cortisol reactivity to challenge in early childhood plays a role in children's cumulative cortisol exposure and behavioral development suggests pathways through which cortisol reactivity may influence long-term physical and mental health.

Telomere Length in Preterm Infants: A Promising Biomarker of Early Adversity and Care in the Neonatal Intensive Care Unit?

Preterm infants present an immature neurobehavioral profile at birth, even in absence of severe brain injuries and perinatal complications. As such, they require a long-lasting hospitalization in the Neonatal Intensive Care Unit (NICU), which is thought to grant at-risk newborns' survival, but still entails a number of physical, painful, and socio-emotional stressors. Hence, preterm birth and NICU stay represent an early adverse experience, which has been linked to detrimental consequences for neurological, neuro-endocrinal, behavioral, and socio-emotional development, as well as to disease later in life. Recent advances in the behavioral epigenetic field are helping us to unveil the potential mechanisms through which early NICU-related stress may lead to negative developmental outcomes. From this perspective, telomere regulation might be a key programming mechanism. Telomeres are the terminal portion of chromosomes and are known to get shorter with age. Moreover, telomere length (TL) is affected by the exposure to stress during early development. As such, TL might be an innovative biomarker of early adverse exposures in young infants and children. Unfortunately, there is paucity of studies investigating TL in populations of preterm infants and its association with known NICU-related stressors remains unexplored. In the present paper, the potential relevance of TL for research and clinical work with preterm infants will be underlined in the light of recent contributions linking progressive telomere shortening and early exposure to adverse experiences and stressful environments in humans. Finally, insights will be provided to guide clinically relevant translational research on TL in the field of VPT birth and NICU stay.

Associations Between Hormonal Biomarkers and Cognitive, Motor, and Language Developmental Status in Very Low Birth Weight Infants

BACKGROUND

Male infants are more prone to health problems and developmental delays than female infants.

OBJECTIVES

On the basis of theories of gender differences in brain development and social relationships, we explored associations between testosterone and cortisol levels with infant cognitive, motor, and language development ("infant development") in very low birth weight (VLBW) infants, controlling for mother-infant interactions, characteristics of mothers and infants, and days of saliva collection after birth.

METHODS

A total of 62 mother-VLBW infant pairs were recruited from the newborn intensive care unit of a tertiary medical center in the Southeast United States. Data were collected through infant medical record review, biochemical measurement, observation of mother-infant interactions, and standard questionnaires. Infant development was assessed at 6 months corrected age (CA), and mother-infant interactions were observed at 3 and 6 months CA.

RESULTS

General linear regression with separate analyses for each infant gender showed that high testosterone levels were positively associated with language development of male infants after controlling for mother-infant interactions and other covariates, whereas high cortisol levels were negatively associated with motor development of female infants after controlling for mother-infant interactions.

CONCLUSIONS

Steroid hormonal levels may well be more fundamental factors for assessing infant development than infant gender or mother-infant interactions at 6 months CA.

Birth weight and postnatal growth in preterm born children are associated with cortisol in early infancy, but not at age 8 years

BACKGROUND

Preterm birth has been associated with altered hypothalamic-pituitary-adrenal (HPA-) axis activity as well as cardiometabolic diseases and neurodevelopmental impairments later in life. We assessed cortisol from term age to age 8 y in children born preterm, to explore the development of HPA-axis activity in association with intrauterine and early-postnatal growth until 6 mo. corrected age.

METHODS

In 152 children born at a gestational age ≤32 wks. and/or with a birth weight ≤1,500g, random serum cortisol was assessed at term age (n=150), 3 mo. (n=145) and 6 mo. corrected age (n=144), and age 8 y (n=59). Salivary cortisol was assessed at age 8 y (n=75): prior to bedtime, at awakening, 15min after awakening, and before lunch. Cortisol was analyzed in association with birth weight-standard deviation score (SDS), being born small for gestational age (SGA), and combinations of intrauterine and postnatal growth: appropriate for gestational age (AGA) with or without growth restriction (AGA GR+ or AGA GR-) at 6 mo. corrected age, and SGA with or without catch-up growth (SGA CUG+ or SGA CUG-) at 6 mo. corrected age. Cross-sectional associations at all time points were analyzed using linear regression, and longitudinal associations were analyzed using generalized estimating equations.

RESULTS

Longitudinally, birth weight-SDS was associated with cortisol (β [95%CI]): lower cortisol over time was seen in infants with a birth weight ≤-2 SDS (-50.69 [-94.27; -7.11], p=0.02), infants born SGA (-29.70 [-60.58; 1.19], p=0.06), AGA GR+ infants (-55.10 [-106.02; -4.17], p=0.03) and SGA CUG- infants (-61.91 [-104.73; -19.10], p=0.01). In cross-sectional analyses at age 8 y, no associations were found between either serum or salivary cortisol and birth weight-SDS, SGA-status, or growth from birth to 6 mo. corrected age.

CONCLUSION

In children born preterm, poor intrauterine and postnatal growth were associated with lower cortisol in early infancy, but not at age 8 y. Even though HPA-axis activity no longer differed between groups at age 8 y, or differences could not be confirmed due to attrition, it is unknown whether the differences found in early infancy could attribute to increased health risks later in life.

Chronic stress in the mother-infant dyad: Maternal hair cortisol, infant salivary cortisol and interactional synchrony

Stress physiology is shaped by early experience, with enduring effects on health. The relation of chronic maternal physiological stress, as indexed by hair cortisol, to infants' stress systems and to mother-infant interaction quality has not been established. We examined maternal hair and salivary cortisol, six-month-old infants' salivary cortisol, and mother-infant interaction in 121 mother-infant dyads. High maternal hair cortisol was related to higher infant average salivary cortisol concentration. Maternal hair cortisol and bedtime salivary cortisol were both uniquely related to infant bedtime salivary cortisol. Mothers with higher hair cortisol were more intrusive and had lower positive engagement synchrony with their infants. Maternal intrusiveness moderated the association of maternal hair cortisol and infant salivary cortisol, such that maternal hair and infant average salivary cortisol were related only when mothers were more intrusive. Maternal chronic physiological stress may upregulate infants' developing stress systems, particularly in the context of lower mother-infant interaction quality.

Self-Reported Mental Health Problems Among Adults Born Preterm: A Meta-analysis

CONTEXT

Preterm birth increases the risk for mental disorders in adulthood, yet findings on self-reported or subclinical mental health problems are mixed.

OBJECTIVE

To study self-reported mental health problems among adults born preterm at very low birth weight (VLBW; ≤1500 g) compared with term controls in an individual participant data meta-analysis.

DATA SOURCES

Adults Born Preterm International Collaboration.

STUDY SELECTION

Studies that compared self-reported mental health problems using the Achenbach Young Adult Self Report or Adult Self Report between adults born preterm at VLBW (n = 747) and at term (n = 1512).

DATA EXTRACTION

We obtained individual participant data from 6 study cohorts and compared preterm and control groups by mixed random coefficient linear and Tobit regression.

RESULTS

Adults born preterm reported more internalizing (pooled β = .06; 95% confidence interval .01 to .11) and avoidant personality problems (.11; .05 to .17), and less externalizing (-.10; -.15 to -.06), rule breaking (-.10; -.15 to -.05), intrusive behavior (-.14; -.19 to -.09), and antisocial personality problems (-.09; -.14 to -.04) than controls. Group differences did not systematically vary by sex, intrauterine growth pattern, neurosensory impairments, or study cohort.

LIMITATIONS

Exclusively self-reported data are not confirmed by alternative data sources.

CONCLUSIONS

Self-reports of adults born preterm at VLBW reveal a heightened risk for internalizing problems and socially avoidant personality traits together with a lowered risk for externalizing problem types. Our findings support the view that preterm birth constitutes an early vulnerability factor with long-term consequences on the individual into adulthood.

Mother-child adrenocortical synchrony; Moderation by dyadic relational behavior

Mother-child adrenocortical synchrony, the coupling of cortisol (CT) secretion in mother and child, has been associated with shared parent-child experiences and maladaptive familial contexts. Yet, few studies tested adrenocortical synchrony in diurnal CT patterns. Guided by the bio-behavioral synchrony model, we examined whether mother-child relational behavior and maternal psychopathology may moderate the degree of concordance between mother and child's diurnal CT. Ninety-seven mothers and their six-year old children participated in two groups; mothers diagnosed with major depression disorder (N=28) and non-depressed controls (N=69). Mother-child interactions were observed and coded for dyadic reciprocity and dyadic tension and diurnal cortisol was collected from mother and child over two consecutive weekend days. Concordance between maternal and child's diurnal CT was found, significant above and beyond time of measurement. Maternal depression, while associated with attenuated child diurnal CT variability, was unrelated to adrenocortical synchrony. Higher child diurnal CT production predicted a stronger linkage between maternal and child's diurnal CT, suggesting that greater child physiological stress is associated with increased susceptibility to the influences of maternal stress physiology. Mother-child reciprocity was related to lower adrenocortical synchrony. Findings suggest that higher adrenocortical synchrony is associated with greater physiological stress and less adaptive dyadic relational patterns. Results raise the possibility that diurnal adrenocortical synchrony taps a unique aspect of HPA-axis functioning whose role in the cross-generational transfer of stress physiology requires further research.

Neonatal repetitive pain in rats leads to impaired spatial learning and dysregulated hypothalamic-pituitary-adrenal axis function in later life

Preterm birth is a major health issue. As part of their life-saving care, most preterm infants require hospitalization and are inevitably exposed to repetitive skin-breaking procedures. The long-term effects of neonatal repetitive pain on cognitive and emotional behaviors involving hypothalamic-pituitary-adrenal (HPA) axis function in young and adult rats are unknown. From P8 to P85, mechanical hypersensitivity of the bilateral hindpaws was observed in the Needle group (P < 0.001). Compared with the Tactile group, the Needle group took longer to find the platform on P30 than on P29 (P = 0.03), with a decreased number of original platform site crossings during the probe trial of the Morris water maze test (P = 0.026). Moreover, the Needle group spent more time and took longer distances in the central area than the Tactile group in the Open-field test, both in prepubertal and adult rats (P < 0.05). The HPA axis function in the Needle group differed from the Tactile group (P < 0.05), with decreased stress responsiveness in prepuberty and puberty (P < 0.05) and increased stress responsiveness in adulthood (P < 0.05). This study indicates that repetitive pain that occurs during a critical period may cause severe consequences, with behavioral and neuroendocrine disturbances developing through prepuberty to adult life.

Diurnal Cortisol Patterns and Dexamethasone Suppression Test Responses in Healthy Young Adults Born Preterm at Very Low Birth Weight

Background

Early life stress, such as painful and stressful procedures during neonatal intensive care after preterm birth, can permanently affect physiological, hormonal and neurobiological systems. This may contribute to altered programming of the hypothalamic-pituitary-adrenal axis (HPAA) and provoke changes in HPAA function with long-term health impacts. Previous studies suggest a lower HPAA response to stress in young adults born preterm compared with controls born at term. We assessed whether these differences in HPAA stress responsiveness are reflected in everyday life HPAA functioning, i.e. in diurnal salivary cortisol patterns, and reactivity to a low-dose dexamethasone suppression test (DST), in unimpaired young adults born preterm at very low birth weight (VLBW; <1500 g).

Methods

The participants were recruited from the Helsinki Study of Very Low Birth Weight Adults cohort study. At mean age 23.3 years (2.1 SD), 49 VLBW and 36 controls born at term participated in the study. For cortisol analyzes, saliva samples were collected on two consecutive days at 0, 15, 30 and 60 min after wake-up, at 12:00 h, 17:00 h and 22:00 h. After the last salivary sample of the first study day the participants were instructed to take a 0.5 mg dexamethasone tablet.

Results

With mixed-effects model no difference was seen in overall diurnal salivary cortisol between VLBW and control groups [13.9% (95% CI: -11.6, 47.0), P = 0.31]. Salivary cortisol increased similarly after awakening in both VLBW and control participants [mean difference -2.9% (29.2, 33.0), P = 0.85]. Also reactivity to the low-dose DST (awakening cortisol ratio day2/day1) was similar between VLBW and control groups [-1.1% (-53.5, 103.8), P = 0.97)].

Conclusions

Diurnal cortisol patterns and reactivity to a low-dose DST in young adulthood were not associated with preterm birth.

SLC6A4 promoter region methylation and socio-emotional stress response in very preterm and full-term infants

Aim: The present study is part of a prospective micro-longitudinal research project and reports on the association between SLC6A4 methylation and socio-emotional stress response in very preterm (VPT) and full-term (FT) infants. Materials & methods: SLC6A4 methylation was assessed at birth and discharge in 32 VPT infants, and at birth in 27 FT infants. Socio-emotional stress response (i.e., negative emotionality) was assessed at 3 months (corrected age). Results: Negative emotionality was higher in VPTs compared with FT counterpart. In VPT infants only, stress response was associated with SLC6A4 methylation status at discharge, which was predictive of greater negative emotionality. Conclusion: The present study extends previous reports, suggesting that altered SLC6A4 methylation associates with greater socio-emotional stress sensitivity in 3-month-old VPT infants.

Dynamic Changes in DNA Methylation Occur during the First Year of Life in Preterm Infants

BACKGROUND

Preterm birth associates with a substantially increased risk of later cardiovascular disease and neurodevelopmental disorders. Understanding underlying mechanisms will facilitate the development of screening and intervention strategies to reduce disease risk. Changes in DNA methylation have been proposed as one mechanism linking the early environment with later disease risk. We tested the hypothesis that preterm birth associates with altered DNA methylation in genes encoding insulin-like growth factor 2 (IGF2) and FK506-binding protein 5 (FKBP5), which appear particularly vulnerable to early life adversity.

METHODS

Fifty preterm infants were seen and assessed at birth, term equivalent age, 3 months and 1-year corrected ages; 40 term infants were seen at birth, 3 months and 1 year. Saliva was collected for DNA extraction at birth, term, and 1 year. Pyrosequencing of bisulfite-converted DNA was performed to measure DNA methylation at specific CpG sites within the IGF2 and FKBP5 loci.

RESULTS

Weight and head circumference was reduced in preterm infants at all time points. Preterm infants had a higher percentage body fat at term-corrected age, but this difference was not persistent. DNA methylation at the differentially methylated region (DMR) of IGF2 (IGF2DMR2) and FKBP5 was lower in preterm infants at birth- and term-corrected age compared to term infants at birth. IGF2DMR2 and FKBP5 methylation was related to birthweight SD score in preterm infants. Among preterm infants, social deprivation was an independent contributor toward reducing DNA methylation at IGF2DMR2 at birth- and term-corrected age and maternal smoking was associated with reduced DNA methylation at FKBP5 at birth. There were no persistent differences in DNA methylation at 1 year of age.

CONCLUSION

Changes in DNA methylation were identified at key regions of IGF2/H19 and FKBP5 in preterm infants in early life. Potential contributing factors include maternal smoking and social deprivation. However, these changes did not persist at 1 year of age and further longitudinal studies are required to determine any associations between altered DNA methylation in the perinatal period of individuals born preterm and their long-term health.

The Val66Met brain-derived neurotrophic factor gene variant interacts with early pain exposure to predict cortisol dysregulation in 7-year-old children born very preterm: Implications for cognition

Early stress in the form of repetitive neonatal pain, in infants born very preterm, is associated with long-term dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and with poorer cognitive performance. Brain-derived neurotrophic factor (BDNF) which is important in synaptic plasticity and cognitive functions is reduced by stress. Therefore the BDNF Val66Met variant, which affects secretion of BDNF, may interact with early exposure to pain-related stress in children born very preterm, to differentially affect HPA regulation that in turn may be associated with altered cognitive performance. The aims of this study were to investigate whether in children born very preterm, the BDNF Val66Met variant modulates the association between neonatal pain-related stress and cortisol levels at age 7years, and if cortisol levels were related to cognitive function. Furthermore, we examined whether these relationships were sex-specific. Using a longitudinal cohort design, N=90 children born very preterm (24-32weeks gestation) were followed from birth to age 7years. Cortisol was assayed from hair as an index of cumulative stress and from saliva to measure reactivity to a cognitive challenge. BDNF Val66Met variant was genotyped at 7years using real-time polymerase chain reaction (PCR). Using generalized linear modeling, in boys with the Met allele, greater neonatal pain-related stress (adjusted for clinical risk factors) predicted lower hair cortisol (p=0.006) and higher reactivity salivary cortisol (p=0.002). In both boys and girls with the Met allele, higher salivary cortisol reactivity was correlated with lower IQ (r=-0.60; p=0.001) and poorer visual-motor integration (r=-0.48; p=0.008). Our findings show associations between lower BDNF availability (presence of the Met allele) and vulnerability to neonatal pain/stress in boys, but not girls. This exploratory study suggests new directions for research into possible mechanisms underlying how neonatal pain/stress is related to cognitive performance in children born very preterm.

Stress in parents of children born very preterm is predicted by child externalising behaviour and parent coping at age 7 years

OBJECTIVE

To examine factors which predict parenting stress in a longitudinal cohort of children born very preterm, and seen at age 7 years.

METHODS

We recruited 100 very preterm (≤32 weeks gestational age) child-parent dyads and a control group of 50 term-born dyads born between 2001 and 2004 with follow-up at 7 years. Parents completed the Parenting Stress Index, Ways of Coping Questionnaire, Child Behavior Check List, Beck Depression Inventory and the State Trait Anxiety Inventory questionnaires. Child IQ was assessed using the Wechsler Intelligence Scale-IV.

RESULTS

After controlling for maternal education, parents of preterm children (95% CI 111.1 to 121.4) scored higher (p=0.027) on the Parenting Stress Index than term-born controls (95% CI 97.8 to 113.2). Regression analyses showed that child externalising behaviour, sex and parent escape/avoidance coping style, predicted higher parenting stress in the preterm group. Parents of preterm girls expressed higher levels of stress than those of boys.

CONCLUSIONS

Maladaptive coping strategies contribute to greater stress in parents of very preterm children. Our findings suggest that these parents need support for many years after birth of a very preterm infant.

Cortisol levels in former preterm children at school age are predicted by neonatal procedural pain-related stress

Early life stress can alter hypothalamic pituitary adrenal (HPA) axis function. Differences in cortisol levels have been found in preterm infants exposed to substantial procedural stress during neonatal intensive care, compared to infants born full-term, but only a few studies investigated whether altered programming of the HPA axis persists past toddler age. Further, there is a dearth of knowledge of what may contribute to these changes in cortisol. This prospective cohort study examined the cortisol profiles in response to the stress of cognitive assessment, as well as the diurnal rhythm of cortisol, in children (n=129) born at varying levels of prematurity (24-32 weeks gestation) and at full-term (38-41 weeks gestation), at age 7 years. Further, we investigated the relationships among cortisol levels and neonatal procedural pain-related stress (controlling for multiple medical confounders), concurrent maternal factors (parenting stress, depressive and anxiety symptoms) and children's behavioral problems. For each aim we investigate acute cortisol response profiles to a cognitive challenge as well as diurnal cortisol patterns at home. We hypothesized that children born very preterm will differ in their pattern of cortisol secretion from children born full-term, possibly depended on concurrent child and maternal factors, and that exposure to neonatal pain-related stress would be associated with altered cortisol secretion in children born very preterm, possibly in a sex-dependent way. Saliva samples were collected from 7-year old children three times during a laboratory visit for assessment of cognitive and executive functions (pretest, mid-test, end-study day acute stress profile) and at four times over two consecutive non-school days at home (i.e. morning, mid-morning, afternoon and bedtime-diurnal rhythm profile). We found that cortisol profiles were similar in preterm and full-term children, albeit preterms had slightly higher cortisol at bedtime compared to full-term children. Importantly, in the preterm group, greater neonatal procedural pain-related stress (adjusted for morphine) was associated with lower cortisol levels on the study day (p=.044) and lower diurnal cortisol at home (p=.023), with effects found primarily in boys. In addition, child attention problems were negatively, and thought problems were positively, associated with the cortisol response during cognitive assessment on the study day in preterm children. Our findings suggest that neonatal pain/stress contributes to altered HPA axis function up to school-age in children born very preterm, and that sex may be an important factor.

Five-year follow-up of effects of neonatal intensive care and morphine infusion during mechanical ventilation on diurnal cortisol rhythm

OBJECTIVE

To test the hypothesis that the diurnal cortisol secretion rhythm of children who as neonates had been hospitalized differs from that of children without a history of neonatal hospital admission and that this rhythm differs between these hospitalized children treated with either continuous morphine infusion or placebo.

STUDY DESIGN

A follow-up cohort study was performed with 5-year-old children who as neonates participated in a randomized controlled trial of continuous morphine infusion (born 24-42 weeks' gestation), and a control group of healthy term born (≥ 37 weeks' gestation) children. Five saliva samples over a school day were assayed for cortisol concentrations. The diurnal cortisol rhythm was analyzed with random regression analysis for repeated measurements.

RESULTS

Compared with the healthy controls, the trial participants had greater cortisol levels (P = .002) after adjustment for sex and socioeconomic status. The administration of morphine did not affect the cortisol concentrations (P = .66) after adjustment for sex, socioeconomic status, and gestational age at birth.

CONCLUSIONS

The finding that former trial participants had greater cortisol levels at 5 years of age supports the concept of long-lasting programming of the hypothalamic-pituitary-adrenal axis. Morphine infusion in the neonatal period did not alter cortisol secretion at 5 years of age.

Adrenalin, noradrenalin and heart rate responses to psychosocial stress in young adults born preterm at very low birthweight

OBJECTIVE

Adults born preterm at very low birthweight (VLBW; ≤ 1500 g) have high levels of cardiovascular risk factors and altered responses to psychosocial stress including higher blood pressure and lower cortisol. Our aim was to investigate adrenalin (A), noradrenalin (NA) and heart rate (HR) responses to psychosocial stress in adults born preterm at VLBW.

DESIGN AND PARTICIPANTS

We studied 50 young adults, aged 19-27 years, born at VLBW and 39 term-born controls, group-matched for age, sex and birth hospital. They underwent a standardized psychosocial stress test, the Trier Social Stress Test (TSST).

MEASUREMENTS

During TSST, A, NA (baseline and 0, 10 and 90 min after stress) and HR were measured. Data were analysed with mixed-effects and linear regression models, adjusted for age, sex, body mass index, hormonal contraception, time of day and highest parental educational attainment.

RESULTS

Baseline concentrations, peak after stress, increments and area under the curve for A and NA were similar in VLBW and control groups. In women, NA concentrations were 27.7% lower (95% CI; 3.1-52.2) in VLBW compared with control women; in men, there was no significant difference. A concentrations were similar for VLBW and control groups in both sexes. Mean HR at baseline, task and HR reactivity was also similar in VLBW and control groups.

CONCLUSIONS

Very low-birthweight women seem to have a lower NA response to stress compared with term-born peers. If replicated, this could be a protective characteristic for cardiovascular diseases.

Effects of hatching time on behavior and weight development of chickens

The length of the embryonic period varies both among and within species and can affect the individual phenotype in many ways, both physiologically and behaviorally. In chickens, the hatch window may last 24–48 hours (up to 10% of the incubation time), and studies have shown that incubation length may affect post-hatch growth and physiology. However, little is known about effects on behavior. We therefore investigated how behavior variation correlates with hatching time in the early life of chickens. We also measured egg weight and egg weight loss in relation to hatching time, as well as post-hatch growth. For females, there was a negative correlation between hatch time and body weight from day 4 and throughout the experiment. For males, such a correlation was only observed when testing all hatched males up until day 10. The birds were exposed to a number of behavioral tests, and a principal components analysis was performed on the variables, resulting in four components. For the largest component, termed “Passivity”, a tendency of a difference was found between early and middle male hatchers. Furthermore, a significant difference between early and middle male hatchers was found in the second component, termed “Response to novelty”. In a spatial learning test, late hatchers tended to learn slower. The behavior of females was not significantly affected by hatching time in any of these tests. This study is among the first to demonstrate a link between time of hatching and early behavior in a precocial species like the chicken, and may help shedding light on the evolutionary trade-offs between incubation length and post-hatch traits. The results may also be relevant from a perspective of stress coping and therefore also for animal welfare and productivity in the chicken industry. The mechanisms linking hatching time with post-hatch phenotype remain to be investigated.

Preterm delivery as a predictor of diurnal cortisol profiles in adulthood: evidence from Cebu, Philippines

OBJECTIVES

Fetal exposure to elevated maternal cortisol can permanently modify hypothalamic-pituitary-adrenal (HPA) axis function, and thereby have long-term health impacts. Maternal cortisol steadily increases throughout normal pregnancy, but is abnormally high in preterm deliveries (<37 weeks). Prematurity remains a widespread public health problem, yet little is known about its potential long-term effects on adult HPA function. Here we test the hypothesis that diurnal cortisol profiles measured in young adulthood will vary based upon an individual's preterm status.

METHODS

Diurnal salivary cortisol profiles, a marker of HPA-axis function, were measured in 1,403 young adults (ages 21-23 years) participating in the Cebu Longitudinal Health and Nutrition Survey, located in Metropolitan Cebu City, Philippines.

RESULTS

Males who had been born preterm exhibited lower morning cortisol and non-significantly elevated evening cortisol, resulting in a more adverse, flatter rate of decline across the day. In contrast, there were no significant differences by preterm status in cortisol measured at any time of day in females.

CONCLUSIONS

These findings point to potential long-term effects of having been born preterm on adult HPA-axis function, and add to evidence from this and other populations for sex differences in the biological and health impacts of prenatal stress exposure.

Impact of repeated procedural pain-related stress in infants born very preterm

The majority of infants born very preterm (24-32 wk gestational age) now survive; however, long-term neurodevelopmental and behavioral problems remain a concern. As part of their neonatal care, very preterm infants undergo repeated painful procedures during a period of rapid brain development and programming of stress systems. Infants born this early have the nociceptive circuitry required to perceive pain, however, their sensory systems are functionally immature. An imbalance of excitatory vs. inhibitory processes leads to increased nociceptive signaling in the central nervous system. Specific cell populations in the central nervous system of preterm neonates are particularly vulnerable to excitoxicity, oxidative stress, and inflammation. Neonatal rat models have demonstrated that persistent or repeated pain increases apoptosis of neurons, and neonatal pain and stress lead to anxiety-like behaviors during adulthood. In humans, greater exposure to neonatal pain-related stress has been associated with altered brain microstructure and stress hormone levels, as well as with poorer cognitive, motor, and behavioral neurodevelopment in infants and children born very preterm. Therefore, it is important that pain-related stress in preterm neonates is accurately identified, appropriately managed, and that pain management strategies are evaluated for protective or adverse effects in the long term.

Brain injury in premature neonates: A primary cerebral dysmaturation disorder?

With advances in neonatal care, preterm neonates are surviving with an evolving constellation of motor and cognitive disabilities that appear to be related to widespread cellular maturational disturbances that target cerebral gray and white matter. Whereas preterm infants were previously at high risk for destructive brain lesions that resulted in cystic white matter injury and secondary cortical and subcortical gray matter degeneration, contemporary cohorts of preterm survivors commonly display less severe injury that does not appear to involve pronounced glial or neuronal loss. Nevertheless, these milder forms of injury are also associated with reduced cerebral growth. Recent human and experimental studies support that impaired cerebral growth is related to disparate responses in gray and white matter. Myelination disturbances in cerebral white matter are related to aberrant regeneration and repair responses to acute death of premyelinating late oligodendrocyte progenitors (preOLs). In response to preOL death, early oligodendrocyte progenitors rapidly proliferate and differentiate, but the regenerated preOLs fail to normally mature to myelinating cells required for white matter growth. Although immature neurons appear to be more resistant to cell death from hypoxia-ischemia than glia, they display widespread disturbances in maturation of their dendritic arbors, which further contribute to impaired cerebral growth. These complex and disparate responses of neurons and preOLs thus result in large numbers of cells that fail to fully mature during a critical window in development of neural circuitry. These recently recognized forms of cerebral gray and white matter dysmaturation raise new diagnostic challenges and suggest new therapeutic directions centered on reversal of the processes that promote dysmaturation.

Blunted hypothalamic-pituitary-adrenal axis and insulin response to psychosocial stress in young adults born preterm at very low birth weight

BACKGROUND

Young adults born preterm at very low birth weight (VLBW, ≤1500 g) have higher levels of cardiovascular risk factors, including impaired glucose regulation, than their term-born peers. This could be mediated through altered hypothalamic-pituitary-adrenal axis (HPAA) response to stress.

OBJECTIVE

To compare HPAA, glucose and insulin responses provoked by psychosocial stress in VLBW subjects versus a comparison group of term-born controls.

DESIGN AND PARTICIPANTS

We studied 54 unimpaired young adults, aged 19-27 years, born at VLBW and a comparison group of 40 adults born at term, group-matched for age, sex and birth hospital, from one regional centre in southern Finland. The participants underwent a standardized psychosocial stress test (Trier Social Stress Test, TSST).

MEASUREMENTS

In conjunction with TSST, we measured salivary cortisol, plasma ACTH, cortisol, glucose and insulin. Data were analysed with mixed-effects model and multiple linear regression analyses.

RESULTS

Baseline concentrations for cortisol, ACTH, insulin and glucose were similar in VLBW and comparison groups. During TSST, analysed with mixed-effects model, overall concentrations of plasma cortisol were 17·2% lower (95% CI; 3·5 to 28·9) in the VLBW group. The VLBW group also had lower salivary (P = 0·04) and plasma cortisol (P = 0·02) responses to TSST. Insulin and glucose concentrations correlated with changes in cortisol concentrations. Accordingly, VLBW subjects had 26·5% lower increment in insulin (95% CI; 9·8-40·1). Analyses were adjusted for age, sex, body mass index, hormonal contraception, menstrual cycle phase, time of day and parental education.

CONCLUSIONS

VLBW adults have lower HPAA responses to psychosocial stress than term-born controls. This is accompanied by a lower insulin response.

Biological and neurodevelopmental implications of neonatal pain

Nociceptive pathways are functional following birth. In addition to physiological and behavioral responses, neurophysiological measures and neuroimaging evaluate nociceptive pathway function and quantify responses to noxious stimuli in preterm and term neonates. Intensive care and surgery can expose neonates to painful stimuli when the developing nervous system is sensitive to changing input, resulting in persistent impacts into later childhood. Early pain experience has been correlated with increased sensitivity to subsequent painful stimuli, impaired neurodevelopmental outcomes, and structural changes in brain development. Parallel preclinical studies have elucidated underlying mechanisms and evaluate preventive strategies to inform future clinical trials.