Cortisol reactivity in young infants

Effects of pain, sedation and analgesia on neonatal brain injury and brain development

Critically ill newborns experience numerous painful procedures as part of lifesaving care in the Neonatal Intensive Care Unit. However, painful exposures in the neonatal period have been associated with alterations in brain maturation and poorer neurodevelopmental outcomes in childhood. The most frequently used medications for pain and sedation in the NICU are opioids, benzodiazepines and sucrose; these have also been associated with abnormalities in brain maturation and neurodevelopment making it challenging to know what the best approach is to treat neonatal pain. This article provides clinicians with an overview of how neonatal exposure to pain as well as analgesic and sedative medications impact brain maturation and neurodevelopmental outcomes in critically ill infants. We also highlight areas in need of future research to develop standardized neonatal pain monitoring and management strategies.

The effect of stress on the antibody response after vaccination in children aged 0-18 years: A systematic review

Stress has been associated with less effective vaccine responses in adults. This review aims to investigate the evidence for a similar association in children. A systematic review search was conducted in January 2021 in three databases: Medline, Embase and PsycInfo. An updated search of the Medline database was systematically conducted until the most recent update on September 25th, 2023, to ensure the inclusion of the most current research available. Keywords related to stress, vaccines and children were used, and a total of 7263 (+1528) studies were screened by two independent investigators. Six studies met the inclusion criteria for data extraction and analysis. For quality assessment of the studies, the risk of bias in non-randomized studies-of interventions (ROBINS-I) tool was applied. Most of the studies suggest a negative role of stress on vaccine responses. However, the scarcity of studies, lack of confirmatory studies, risk of bias and heterogeneity according to age, type of vaccine, measures of stress and vaccine responses prevent a clear conclusion. Future studies should emphasize the use of as strict study designs as possible, including well-defined stress metrics and thorough examination of both pre- and post-vaccination responses. Systematic review registration: Prospero CRD42021230490.

Stress biomarkers and child development in young children in Bangladesh

BACKGROUND

Hundreds of millions of children in low- and middle-income countries are exposed to chronic stressors, such as poverty, poor sanitation and hygiene, and sub-optimal nutrition. These stressors can have physiological consequences for children and may ultimately have detrimental effects on child development. This study explores associations between biological measures of chronic stress in early life and developmental outcomes in a large cohort of young children living in rural Bangladesh.

METHODS

We assessed physiologic measures of stress in the first two years of life using measures of the hypothalamic-pituitary-adrenal (HPA) axis (salivary cortisol and glucocorticoid receptor gene methylation), the sympathetic-adrenal-medullary (SAM) system (salivary alpha-amylase, heart rate, and blood pressure), and oxidative status (F2-isoprostanes). We assessed child development in the first two years of life with the MacArthur-Bates Communicative Development Inventories (CDI), the WHO gross motor milestones, and the Extended Ages and Stages Questionnaire (EASQ). We compared development outcomes of children at the 75th and 25th percentiles of stress biomarker distributions while adjusting for potential confounders using generalized additive models, which are statistical models where the outcome is predicted by a potentially non-linear function of predictor variables.

RESULTS

We analyzed data from 684 children (49% female) at both 14 and 28 months of age; we included an additional 765 children at 28 months of age. We detected a significant relationship between HPA axis activity and child development, where increased HPA axis activity was associated with poor development outcomes. Specifically, we found that cortisol reactivity (coefficient -0.15, 95% CI (-0.29, -0.01)) and post-stressor levels (coefficient -0.12, 95% CI (-0.24, -0.01)) were associated with CDI comprehension score, post-stressor cortisol was associated with combined EASQ score (coefficient -0.22, 95% CI (-0.41, -0.04), and overall glucocorticoid receptor methylation was associated with CDI expression score (coefficient -0.09, 95% CI (-0.17, -0.01)). We did not detect a significant relationship between SAM activity or oxidative status and child development.

CONCLUSIONS

Our observations reveal associations between the physiological evidence of stress in the HPA axis with developmental status in early childhood. These findings add to the existing evidence exploring the developmental consequences of early life stress.

Effects of White Noise on Pain Scores and Salivary Cortisol Levels in Surgical Neonates: A Randomized Controlled Trial

BACKGROUND

Neonates experience varying intensities of pain after surgery. While white noise has been used for postoperative pain relief in infants, its effects on neonates after surgery need further exploration.

PURPOSE

This study aimed to evaluate the effects of white noise on pain scores and salivary cortisol levels in surgical neonates.

METHODS

In this randomized controlled trial, 64 neonates scheduled for surgery were recruited and assigned by block randomization into 2 groups. The intervention group listened to white noise at 50 dB, while the control group listened to white noise at 0 dB, for 30 minutes 6 times for 48 hours postoperatively. Pain scores, measured by the COMFORTneo Scale, and salivary cortisol levels were compared.

RESULTS

Although pain scores decreased after surgery in all subjects, no statistically significant difference was observed between the 2 groups (P = .937). There was a significant difference between pre- and postintervention pain scores in the intervention group only (P = .006). Salivary cortisol levels decreased after intervention in the intervention group, but there was no significant difference between pre- and postintervention levels in the 2 groups (P = .716).

IMPLICATIONS FOR PRACTICE

Given the reduction in pain scores and salivary cortisol concentrations after white noise intervention, white noise shows potential as an adjunctive soothing measure for neonates after surgery.

IMPLICATIONS FOR RESEARCH

Future studies are needed to confirm the efficacy and utility of white noise intervention in clinical settings.

Brain health in preterm infants: importance of early-life pain and analgesia exposure

"Everyday" exposures in the neonatal period, such as pain, may impact brain health in preterm infants. Specifically, greater exposure to painful procedures in the initial weeks after birth have been related to abnormalities in brain maturation and growth and poorer neurodevelopmental outcomes in preterm infants. Despite an increasing focus on the importance of treating pain in preterm infants, there is a lack of consensus of optimal approaches to managing pain in this population. This may be due to recent findings suggesting that commonly used analgesic and sedative medications in preterm infants may also have adverse effects of brain maturation and neurodevelopmental outcomes. This review provides an overview of potential impacts of pain and analgesia exposure on preterm brain health while highlighting research areas in need of additional investigations for the development of optimal pain management strategies in this population.

A cluster-randomized trial of water, sanitation, handwashing and nutritional interventions on stress and epigenetic programming

A regulated stress response is essential for healthy child growth and development trajectories. We conducted a cluster-randomized trial in rural Bangladesh (funded by the Bill & Melinda Gates Foundation, ClinicalTrials.gov NCT01590095) to assess the effects of an integrated nutritional, water, sanitation, and handwashing intervention on child health. We previously reported on the primary outcomes of the trial, linear growth and caregiver-reported diarrhea. Here, we assessed additional prespecified outcomes: physiological stress response, oxidative stress, and DNA methylation (N = 759, ages 1-2 years). Eight neighboring pregnant women were grouped into a study cluster. Eight geographically adjacent clusters were block-randomized into the control or the combined nutrition, water, sanitation, and handwashing (N + WSH) intervention group (receiving nutritional counseling and lipid-based nutrient supplements, chlorinated drinking water, upgraded sanitation, and handwashing with soap). Participants and data collectors were not masked, but analyses were masked. There were 358 children (68 clusters) in the control group and 401 children (63 clusters) in the intervention group. We measured four F2-isoprostanes isomers (iPF(2α)-III; 2,3-dinor-iPF(2α)-III; iPF(2α)-VI; 8,12-iso-iPF(2α)-VI), salivary alpha-amylase and cortisol, and methylation of the glucocorticoid receptor (NR3C1) exon 1F promoter including the NGFI-A binding site. Compared with control, the N + WSH group had lower concentrations of F2-isoprostanes isomers (differences ranging from -0.16 to -0.19 log ng/mg of creatinine, P < 0.01), elevated post-stressor cortisol (0.24 log µg/dl; P < 0.01), higher cortisol residualized gain scores (0.06 µg/dl; P = 0.023), and decreased methylation of the NGFI-A binding site (-0.04; P = 0.037). The N + WSH intervention enhanced adaptive responses of the physiological stress system in early childhood.

Influence of mothers' stress on their infants' stress level: A preliminary study

Background

In a previous study, mothers' stress was demonstrated to affect the stress of their infants. However, stress is a multi-layered concept, and there is a lack of studies on the type of stress that influences infant stress.

Objective

This study examined how various types of mothers' stress influence their infants' stress by measuring stress that emanates from COVID-19, child rearing, and stress levels based on speech and cortisol in saliva.

Methods

This study was conducted in two phases, and the stress of 21 mother-infant dyad were evaluated using questionnaires, participants' saliva, and voice recording.

Results

The results demonstrated that maternal stress increased infant stress, rearing stress decreased infant stress, and COVID-19 stress did not affect infant stress. Furthermore, there was no relationship between stress measured using questionnaires and stress measured using saliva, indicating that these factors independently affect infant stress.

Conclusion

It is clear that stress is multi-layered and that it is necessary to grasp each of the various stresses and their relationship appropriately.

Biomarkers for assessing pain and pain relief in the neonatal intensive care unit

Newborns admitted to the neonatal intensive care unit (NICU) regularly undergo painful procedures and may face various painful conditions such as postoperative pain. Optimal management of pain in these vulnerable preterm and term born neonates is crucial to ensure their comfort and prevent negative consequences of neonatal pain. This entails accurate and timely identification of pain, non-pharmacological pain treatment and if needed administration of analgesic therapy, evaluation of treatment effectiveness, and monitoring of adverse effects. Despite the widely recognized importance of pain management, pain assessment in neonates has thus far proven to be a challenge. As self-report, the gold standard for pain assessment, is not possible in neonates, other methods are needed. Several observational pain scales have been developed, but these often rely on snapshot and largely subjective observations and may fail to capture pain in certain conditions. Incorporation of biomarkers alongside observational pain scores holds promise in enhancing pain assessment and, by extension, optimizing pain treatment and neonatal outcomes. This review explores the possibilities of integrating biomarkers in pain assessment in the NICU.

Hair and plasma cortisol throughout the first 3 years of development in infant rhesus macaques, Macaca mulatta

Cortisol expression has been demonstrated to have variation across development in rhesus macaques (Macaca mulatta). There exists contradictory evidence for the nature of this change, and age at which it occurs, across biological sample types. Consequently, we lack a cohesive understanding for cortisol concentrations across the development of a major human health translational model. We examined hair cortisol concentrations over the first 3 years of life for 49 mother-reared infant macaques from mixed-sex outdoor units at the California National Primate Research Center. For 48 of these subjects at infancy, 1 year, and 2 years, we obtained plasma cortisol samples for response to a stressor, adjustment to prolonged stress, and response to dexamethasone injection. Hair cortisol concentrations decreased dramatically between 3 and 10 months, followed by relative stability up to the final sampling event at around 34 months of age. Plasma cortisol showed within-year consistency, and consistency between infancy and year 1. We document variability in the infant plasma cortisol samples, especially in percent change between samples 1 and 2. Our plasma cortisol results indicate that infants possess the physiological capacity to effectively inhibit the release of cortisol when stimulated, as effectively as later responses in juveniles. Age-related changes in hair cortisol parallel findings indicating a large decline in the weeks following postparturation.

Maternal Early Life Adversity and Infant Stress Regulation: Intergenerational Associations and Mediation by Maternal Prenatal Mental Health

Early life adversity is a potent risk factor for poor mental health outcomes across the lifespan, including offspring vulnerability to psychopathology. Developmentally, the prenatal period is a sensitive window in which maternal early life experiences may influence offspring outcomes and demarcates a time when expectant mothers and offspring are more susceptible to stressful and salutary influences. This prenatal plasticity constituted the focus of the current study where we tested the association of maternal early life adversity with infant stress regulation through maternal prenatal internalizing symptoms and moderation by prenatal social support. Mother-infant dyads (n = 162) were followed prospectively and mothers completed assessments of social support and depressive and anxiety symptoms across pregnancy. Infants completed standardized stress paradigms at one month and six months. There were several key findings. First, maternal prenatal depressive symptoms significantly mediated predictions of infant cortisol reactivity to the heel stick at one month from maternal early life adversity: specifically, maternal early life adversity positively predicted depressive symptoms in pregnancy, which in turn predicted dampened infant cortisol reactivity. Second, prenatal social support did not significantly moderate predictions of depressive or anxiety symptoms in pregnancy from maternal early life adversity nor did it alter the associations of maternal depressive or anxiety symptoms with infant stress regulation. These results suggest that maternal prenatal mental health is a key mechanism by which maternal early life adverse experiences affect offspring risk for psychopathology. We discuss potential clinical and health implications of dysregulated infant cortisol reactivity with respect to lifespan development.

Evaluation of procedural pain for neonates in a neonatal intensive care unit: a single-centre study

BACKGROUND

To evaluate the procedural pain experienced by neonates in a neonatal intensive care unit (NICU) setting and determine the corresponding pain grades.

METHODS

Two experienced nurses independently used the Neonatal Infant Pain Scale (NIPS) to evaluate the neonatal pain during procedures taking place in the tertiary NICU and two level-two neonatal care units in the Children's Hospital of Zhejiang University School of Medicine. The mean and distribution of NIPS pain scores and the corresponding pain grades of participants when experiencing clinical painful procedures were analysed.

RESULTS

A total of 957 neonates exposed to 15 common clinical painful procedures were included in the study. The clinical painful procedures experienced by 957 participants could be divided into three groups: severe pain (NIPS score 5-7: peripheral intravenous cannulation, arterial catheterisation, arterial blood sampling, peripherally inserted central catheter placement and nasopharyngeal suctioning), mild to moderate pain (NIPS score 3-4: finger prick, intramuscular injection, adhesive removal, endotracheal intubation suctioning, heel prick, lumbar puncture and subcutaneous injection) and no pain to mild pain (NIPS score 0-2: gastric tube insertion, enema and intravenous injection).

CONCLUSIONS

The neonatal pain response to clinical procedures in NICU had certain pattern and preintervention drug analgesia could be taken for painful procedures with clustered high NIPS pain scores. Meanwhile, full coverage non-drug pain relief measures could be taken for procedures that are with scattered pain scores, and real-time pain evaluation should be provided to determine whether further drug analgesia is required.

Increases in maternal depressive symptoms during pregnancy and infant cortisol reactivity: Mediation by placental corticotropin-releasing hormone

BACKGROUND

Maternal depressive symptoms in pregnancy may affect offspring health through prenatal programming of the hypothalamic-pituitary-adrenal (HPA) axis. The biological mechanisms that explain the associations between maternal prenatal depressive symptoms and offspring HPA axis regulation are not yet clear. This pre-registered investigation examines whether patterns of maternal depressive symptoms in pregnancy are associated with infant cortisol reactivity and whether this association is mediated by changes in placental corticotropin-releasing hormone (pCRH).

METHOD

A sample of 174 pregnant women completed assessments in early, mid, and late pregnancy that included standardized measures of depressive symptoms and blood samples for pCRH. Infant cortisol reactivity was assessed at 1 and 6 months of age.

RESULTS

Greater increases in maternal depressive symptoms in pregnancy were associated with higher cortisol infant cortisol reactivity at 1 and 6 months. Greater increases in maternal depressive symptoms in pregnancy were associated with greater increases in pCRH from early to late pregnancy which in turn were associated with higher infant cortisol reactivity.

CONCLUSIONS

Increases in maternal depressive symptoms and pCRH over pregnancy may contribute to higher infant cortisol reactivity. These findings help to elucidate the prenatal biopsychosocial processes contributing to offspring HPA axis regulation early in development.

Bridging the mood and stress hormone levels between mothers and their babies: The study design and first preliminary results

The neurobiological mechanisms involved in the influence of post-partum maternal mood fluctuations on child development are far from being understood. Here we present the design of an ongoing study aimed to test the hypothesis that the mental state of the mother has an impact on her neonate which is manifested by similarities in the neuroendocrine function of the mother and the child. The hypothesis is being tested under both stress and non-stress conditions in mothers and babies aged 3-4 days and 7-9 months. The focus will be given to correlations with maternal postpartum mood. To confirm the correctness of methodological approaches and the feasibility of the study several preliminary analyses were performed. Salivary alpha-amylase activity as a marker of sympathetic activation and cortisol as the effective hormone of the hypothalamic-pituitary-adrenocortical axis were measured. The obtained results showed the feasibility of saliva sampling in neonates using a sampling time of 120 s. The analysis of cortisol in hair revealed increased concentrations during the third trimester of pregnancy, which is consistent with the knowledge of high cortisol concentrations during pregnancy. A positive correlation was observed between salivary cortisol values before and after the stress test in mother-infant dyads at both the post-partum period and 7-9 months thereafter. Understanding the mechanisms involved in "the bridge" between the mother and her baby will help to develop necessary interventions directed to help mothers in the early postpartum period.

Placenta DNA methylation levels of the promoter region of the leptin receptor gene are associated with infant cortisol

The intrauterine environment and early life stress regulation are widely recognized as an early foundation for lifelong physical and mental health. Methylation of CpG sites in the placenta represents an epigenetic modification that can potentially affect placental function, influence fetal development, and ultimately impact the health of offspring by programming the hypothalamic-pituitary-adrenal (HPA) axis stress response during prenatal development. Leptin, an adipokine produced by the placenta, is essential for energy homeostasis. It is also epigenetically regulated by promoter DNA methylation. Mounting evidence suggests that leptin also affects the stress response system. Though heterogeneity in the early stress response system may influence life-long mental and physical health, few studies explicitly examine the heterogeneity in the newborn stress response system. Less is known about leptin's association with the human hypothalamic-pituitary-adrenocortical (HPA) axis early in life. This study sought to serve as a proof of concept study investigating the relationship between newborn cortisol output trajectories and placental leptin DNA methylation in 117 healthy newborns from socioeconomically and racially- and ethnically-diverse families. We characterized heterogeneity in newborn cortisol output during the NICU Network Neurobehavioral Scales exam in the first week of life with latent growth mixture models. We then evaluated whether leptin promoter (LEP) methylation in placental samples was associated with newborn cortisol trajectories. Our findings suggest that increased placental LEP methylation, which corresponds to decreased leptin production, is associated with infant cortisol trajectories marked by increased cortisol output in the NNNS exam. These results provide important insights into the role of placental leptin DNA methylation in human newborn HPA axis development and subsequent developmental origins of health and disease processes.

Maternal-infant interaction quality is associated with child NR3C1 CpG site methylation at 7 years of age

OBJECTIVE

Infancy is both a critical window for hypothalamic-pituitary-adrenal (HPA) axis development, and a sensitive period for social-emotional influences. We hypothesized that the social-emotional quality of maternal-infant interactions are associated with methylation of HPA-axis gene NR3C1 later in childhood.

METHODS

Using a subsample of 114 mother-infant pairs from the Avon Longitudinal Study of Parents and Children (ALSPAC), linear regression models were created to predict variance in methylation of seven selected CpG sites from NR3C1 in whole blood at age 7 years, including the main predictor variable of the first principal component score of observed maternal-infant interaction quality (derived from the Thorpe Interaction Measure at 12 months of age) and covariates of cell-type proportion, maternal financial difficulties and marital status at 8 months postnatal, child birthweight, and sex.

RESULTS

CpG site cg27122725 methylation was negatively associated with warmer, more positive maternal interaction with her infant (β = 0.19, p = .02, q = 0.13). In sensitivity analyses, the second highest quartile of maternal behavior (neutral, hesitant behavior) was positively associated with cg12466613 methylation. The other five CpG sites were not significantly associated with maternal-infant interaction quality.

CONCLUSIONS

Narrow individual variation of maternal interaction with her infant is associated with childhood methylation of two CpG sites on NR3C1 that may be particularly sensitive to environmental influences. Infancy may be a sensitive period for even small influences from the social-emotional environment on the epigenetic determinants of HPA-axis function.

Parents' Physiological Reactivity to Child Distress and Associations with Parenting Behaviour: A Systematic Review

This systematic review and narrative synthesis characterized parents' physiological stress responses to child distress and how parents' physiological and behavioural responses relate. The review was pre-registered with PROSPERO (#CRD42021252852). In total, 3,607 unique records were identified through Medline, Embase, PsycINFO, and CINAHL. Fifty-five studies reported on parents' physiological stress responses during their young child's (0-3 years) distress and were included in the review. Results were synthesized based on the biological outcome and distress context used and risk of bias was evaluated. Most studies examined cortisol or heart rate variability (HRV). Small to moderate decreases in parents' cortisol levels from baseline to post-stressor were reported across studies. Studies of salivary alpha amylase, electrodermal activity, HRV, and other cardiac outcomes reflected weak or inconsistent physiological responses or a paucity of relevant studies. Among the studies that examined associations between parents' physiological and behavioural responses, stronger associations emerged for insensitive parenting behaviours and during dyadic frustration tasks. Risk of bias was a significant limitation across studies and recommendations for future research are discussed.

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.

Attachment dimensions and cortisol responses during the strange situation among young children adopted internationally

Children's attachments to their parents may help regulate their hypothalamic-pituitary-adrenal (HPA) axes. Prior research has largely focused on children with relatively consistent and low-risk caregiving histories, resulting in limited knowledge about the associations between attachment quality and HPA axis reactivity among children who have experienced early adversity. This study investigated whether dimensional measures of attachment quality were associated with HPA responses to the Strange Situation Procedure (SSP) among 64 children ages 11-33 months adopted internationally from institutional or foster care. Children who showed high levels of attachment avoidance exhibited a blunted cortisol response during the SSP. Conversely, children who sought proximity and contact with their adoptive parents exhibited an increase in cortisol reactivity during the SSP, followed by a return to baseline levels after the completion of the procedure. This association was independent of the previously reported association between parental insensitivity and blunted cortisol responses in this sample.

Effects of skin-to-skin contact on full-term infants' stress reactivity and quality of mother-infant interactions

Skin-to-skin contact (SSC) between mothers and their infants has beneficial effects in both preterm and full-term infants. Underlying mechanisms are largely unknown. This randomized controlled trial assessed whether daily SSC in full-term mother-infant dyads: (1) decreases infants' cortisol and behavioral reactivity to a mild naturalistic stressor, and (2) facilitates interaction quality between infants and mothers (i.e., improved maternal caregiving behavior and mother-infant adrenocortical synchrony). Pregnant Dutch women (N = 116) were recruited and randomly allocated to an SSC or care-as-usual condition. The SSC condition performed 1 h of SSC daily, from birth until postnatal week 5. In week 5, mothers bathed the infant (known mild stressor). Infant and maternal cortisol was sampled at baseline, 25 and 40 min after bathing, and infant and maternal behavior was rated. Results did not indicate effects of SSC on infant behavioral and cortisol reactivity to the bathing session. Similarly, no effect of SSC was found on maternal caregiving behavior and mother-infant adrenocortical synchrony. In conclusion, the findings provide no evidence that daily mother-infant SSC is associated with full-term infants' behavioral and adrenocortical stress reactivity or mother-infant interaction quality. Future studies should replicate these findings and unveil other potential mechanisms underlying beneficial effects of SSC.

A Systematic Review of the Effects of Skin-to-Skin Contact on Biomarkers of Stress in Preterm Infants and Parents

BACKGROUND

Premature infants and their parents experience significant stress related to separation and lifesaving procedures. While evidence suggests that skin-to-skin contact (SSC) is a stress-reducing intervention for both neonates and parents, the mechanisms that underlie its efficacy are not well understood.

OBJECTIVE

Purpose of this systematic review is to summarize the current state of knowledge on changes in biomarkers (ie, oxytocin [OT], cortisol, hypoxanthine, xanthine, uric acid, and allantoin), associated with SSC in premature infants and parents, that may reflect physiologic responses to stress.

METHODS

A comprehensive literature search was conducted from 1990 to 2020. Studies were selected using prespecified inclusion and exclusion criteria.

RESULTS

Of the 175 studies identified, only 19 are included in this review. Ten studies evaluated only infants, 2 evaluated only parents, and 7 evaluated for changes in biomarkers in both infants and parents. Cortisol was the most common biomarker evaluated. While changes in infants' cortisol levels were highly variable, in 55% of the parent studies, parent cortisol levels decreased following SSC. In both parents and infants, OT levels decreased following SSC. Only 1 study found that allantoin levels were significantly lower in infants who received SSC.

IMPLICATIONS FOR PRACTICE AND RESEARCH

While evidence suggests the numerous benefits of SSC, additional research is needed to identify the optimal biomarker to determine the mechanisms that underlie these effects. The use of novel biomarkers (eg, gene expression changes microbiome) may provide new insights into the mechanisms that underlie the efficacy of SSC.Video Abstract available at:https://journals.lww.com/advancesinneonatalcare/Pages/videogallery.aspx?autoPlay=false&videoId=48.

Maternal Stress, Early Life Factors and Infant Salivary Cortisol Levels

Background: Salivary cortisol (SC), a commonly used biomarker for stress, may be disrupted by negative events in pregnancy, at birth and in infancy. We aimed to explore if maternal perceived stress (PSS) in or after pregnancy and SC levels in pregnancy were associated with SC in early infancy, and, secondly, to identify early life factors associated with infants’ SC levels (iSC). Methods: At 3 months of age, SC was analyzed in 1057 infants participating in a Nordic prospective mother-child birth cohort study. Maternal PSS was available from questionnaires at 18- and 34-week gestational age (GA) and 3-month post-partum, and SC was analyzed at 18-week GA. Early life factors included sociodemographic and infant feeding from questionnaires, and birth data from medical charts. Associations to iSC were analyzed by Spearman correlation and multinomial logistic regression analyses. Results: In this exploratory study neither PSS at any time point nor maternal SC (mSC) were associated with iSC. Higher birth weight was associated with higher levels of iSC, while inverse associations were observed in infants to a mother not living with a partner and mixed bottle/breastfeeding. Conclusions: Maternal stress was not associated with iSC levels, while birth weight, single motherhood and infant feeding may influence iSC levels.

From Early Micro-Temporal Interaction Patterns to Child Cortisol Levels: Toward the Role of Interactive Reparation and Infant Attachment in a Longitudinal Study

Parental mental disorders increase the risk for insecure attachment in children. However, the quality of caregiver–infant interaction plays a key role in the development of infant attachment. Dyadic interaction is frequently investigated via global scales which are too rough to uncover micro-temporal mechanisms. Prior research found that the latency to reparation of uncoordinated dyadic states is associated with infant behavioral and neuroendocrine regulation. We investigated the hypothesis that this interactive mechanism is critical in predicting secure vs. insecure attachment quality in infancy. We also assessed the predictive quality of infant attachment regarding neuroendocrine reactivity later in childhood. A subsample of N = 58 dyads (n = 22 mothers with anxiety disorders, n = 36 controls) from a larger study were analyzed. At 3–8 months postpartum, maternal anxiety disorders were diagnosed via a structured clinical interview as well as dyadic interaction during the Face-to-Face-Still-Face (FFSF) was observed and coded on a micro-temporal scale. Infant attachment quality was assessed with the strange situation paradigm at 12–24 months of age. In an overlapping subsample of N = 39 (n = 13 mothers with anxiety disorder; n = 26 controls), we assessed child cortisol reactivity at 5 to 6 years of age. Generalized linear modeling revealed that longer latencies to interactive reparation during the reunion episode of the FFSF as well as maternal diagnosis at 3–8 months of age predict insecure attachment in children aged 12–24 months. Cox regressions demonstrated that dyads with infants who developed insecure attachment at 12–24 months of age were 48% less likely to achieve an interactive reparation at 3–8 months of age. Mixed models revealed that compared to securely attached children, children who had developed an insecure attachment at 12–24 months of age had an increased cortisol reactivity at 5 to 6 years of age during free play. The results confirm the hypothesis that the development of attachment is affected by experienced micro-temporal interactive patterns besides diagnostic categories. They also showed that infants of mothers with postpartum anxiety disorders have a more than fivefold increased risk of developing an insecure attachment than the infants of the control group. Moreover, results imply that these patterns may influence neurohormonal regulation even in preschool aged children.

Age and sex differences in the cortisol stress reactivity and recovery among infants exposed to prenatal psychological distress

BACKGROUND

Altered hypothalamic-pituitary-adrenal axis (HPA) functioning is one of the potential mechanisms bridging exposure to maternal prenatal psychological distress (PPD) and later risk for offspring psychiatric illness. Research on infant cortisol stress reactivity, on scarcely studied recovery and their associations with maternal PPD is needed to clarify these mechanisms. Knowledge on sex differences in prospective settings is largely lacking. We aimed at filling these gaps by building upon our previous report showing that exposure to maternal prenatal depressive and anxiety symptoms associates with slower cortisol recovery among 10-week-old female infants.

METHODS

In all, 363, 205 and 263 infants at 10 weeks, six and 14 months of age from the FinnBrain Birth Cohort Study participated in a stress test comprising of venipuncture and nasopharynx sampling. Five saliva cortisol samples were collected during each visit to measure cortisol reactivity and recovery. PPD was assessed from maternal self-reports for depressive, anxiety and pregnancy-related anxiety symptoms at gestational weeks 14, 24 and 34.

RESULTS

An 11% enhanced recovery among 14-month-old females was associated with higher depressive and anxiety symptoms (95% CI=1-23%) and pregnancy-related anxiety symptoms (2-21%). No alterations in the female cortisol reactivity or male cortisol stress responses were observed.

CONCLUSIONS

The opposite directions in the associations between the PPD exposure and infant cortisol recovery among 10-week-old and 14-month-old females suggest sex- and age-dependent associations between HPA axis functioning and PPD exposure among healthy infants. Follow-up is needed to characterize the impact of this altered negative feedback mechanism on later health.

Advocating for a Collaborative Research Approach on Transgenerational Transmission of Trauma

Since Myers (1915) coined the term 'shell shock' to define the prolonged suffering of soldiers returning from the Great War, the psychological and physical result of distressing experiences, known as trauma, has been of academic interest. Transgenerational transmission of trauma effects has been recorded, demonstrating that on some level, the exposure to trauma of one generation can impact individuals of a subsequent generation (Yehuda & Lehrner, 2018). Observational studies on children of holocaust survivors formed the basis of this trajectory of research (Rakoff, 1966), and eventually this phenomenon became referred to as the transgenerational transmission of trauma (TTT). Since then, TTT has been observed in several contexts, including within families who have experienced high rates historical trauma (O'Neill et al., 2016), within regions high-frequencies of historical war and terrorism (Yehuda & Lehrner, 2018) and those who have undergone famine (Ahmed, 2010). This report aims to outline several pathways (biological, psychological, and sociological) by which trauma may be transmitted across generations. Moreover, it discusses several methods of trauma assessment and the related challenges and benefits. Lastly, this report advocates a biopsychosocial approach - an interdisciplinary model using the interplay of biological, psychological, and social-environmental factors - to research TTT. By promoting the benefits of such an interdisciplinary approach we attempt to break up silos between disciplines and encourage collaboration between academics from various backgrounds researching this topic to better serve individuals impacted by TTT.

Basal cortisol concentrations related to maternal behavior during puppy development predict post-growth resilience in dogs

A prolonged stress hyporesponsive period (SHRP) due to the mother's presence may delay the timing of glucocorticoid (GC) elevation in infants, thereby reducing the excessive stress response that would affect post-growth temperament. In dogs, the SHRP has been suggested to persist until postnatal week (PW) 4; therefore, PW 5, which SHRP may be prolonged by the mother dog, may be a critical point in the developmental stage of dogs to establish stress responsiveness. We conducted a long-term survey on the development of dogs to investigate i) whether the degree of the stress response at PW 5 is determined by maternal behavior and ii) whether it can predict post-growth stress responses and temperament in dogs. As a result, the offspring of mother dogs who had more delivery experience and exhibited more maternal behavior showed higher basal cortisol concentrations at PW 5. These offspring may have acquired less fear response as an individual trait and had relatively quick adaptability, albeit with high cortisol concentrations during exposure to novel environments post-growth, suggesting that high cortisol concentrations at PW 5 are linked to resilience post-growth. Basal cortisol concentrations at PW 7 were not affected by maternal variables and were not associated with cortisol response to novel environments post-growth. GCs are essential hormones that increase the probability of survival. Therefore, the high hypothalamic pituitary adrenal activities of the mother dogs and their offspring in this study may not immediately indicate negative states, and these results prompt a reconsideration of the role of GC in organisms.

Charting a Course towards Resilience Following Adverse Childhood Experiences: Addressing Intergenerational Trauma via Strengths-Based Intervention

Early research on adverse childhood experiences (ACEs) provided staggering evidence of the significant ramifications of ACEs on physical health and functioning. It brought to the forefront the importance of addressing trauma and family dysfunction to enhance public health. Over the past several decades, the study of childhood adversity has blossomed, with expanded conceptualizations and assessments of ACEs. This review brings together various biological, psychological, and sociological principles that inform our understanding of ACEs and our approach to treatment. Specifically, we document the evolution of ACEs research, focusing on the intergenerational impact of ACEs, the importance of incorporating a resilience framework when examining ACEs, and implementing interventions that address adversity across generations and at multiple levels of the social ecology. Evidence is provided to support the evolving perspective that ACEs have long-lasting effects beyond the ACE(s)-exposed individual, with significant attention to the impact of parental ACEs on child development. An intergenerational and multilevel approach to understanding and addressing ACEs offers specific areas to target in interventions and in public policy.

Autonomic, endocrine, and psychological stress responses to different forms of blood draw

Background

Although fingerstick is often favorably compared to venipuncture as a less invasive method of drawing blood for clinical labs, there is little empirical research that compares physical and psychological stress responses to fingerstick vs. venipuncture (blood draw using a needle in the arm) within the same person.

Methods and findings

We assessed changes in cortisol (a stress hormone), heart rate variability (a marker of autonomic stress), and psychological stress in 40 healthy women who completed both venipuncture and fingerstick. Contrary to our predictions, there was a significant decline in cortisol across conditions, with greater decline from pre- to post-draw in response to venipuncture than fingerstick. There were similar patterns of rise and fall in heart rate variability in both types of blood draw, suggestive of mild vasovagal responses. Psychological measures of stress (such as negative emotion and perceived stress) were generally stronger predictors of participant’s reported pain and blood draw preferences than physical stress measures.

Conclusions

These findings challenge the characterization of fingerstick as necessarily “less invasive” than venipuncture, as participant’s stress responses to fingerstick were equivalent to (and for some measures greater than) their response to venipuncture. Heart rate variability response to fingerstick significantly predicted that individual’s vasovagal-like responses to venipuncture, suggesting that measuring heart rate variability during pre-donation hemoglobin testing may identify donors at risk for adverse events during venipuncture.

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.

Parent-Infant Skin-to-Skin Contact and Stress Regulation: A Systematic Review of the Literature

Several studies have focused on neonatal maternal separation (MS) to investigate behavioural and neuroendocrine reactions to lack of contact, but only a few have focused on early separation in the first days or weeks after birth. This literature review investigates the vital importance of contact and touch by exploring how skin-to-skin contact (SSC) regulates stress in the mother-infant relationship. Various databases such as PubMed, Scopus, and ScienceDirect were searched for literature published between 2015 and 2020. From 1141 articles, 22 were declared eligible. The reviewed articles showed how SSC regulates child stress by biological indicators such as the autonomic nervous system (ANS), heart rate variability (HRV), cortisol, and oxytocin. This research concludes the importance of SSC for stress regulation, especially during the COVID-19 pandemic. With no research to date indicating a possible risk of neonatal COVID-19 transmission following SSC, SSC should continue to be practiced for all women, as recommended by the WHO.

Sleep-wake regulation in preterm and term infants

Study Objectives

In adults, wakefulness can be markedly prolonged at the expense of sleep, e.g. to stay vigilant in the presence of a stressor. These extra-long wake bouts result in a heavy-tailed distribution (highly right-skewed) of wake but not sleep durations. In infants, the relative importance of wakefulness and sleep are reversed, as sleep is necessary for brain maturation. Here, we tested whether these developmental pressures are associated with the unique regulation of sleep–wake states.

Methods

In 175 infants of 28–40 weeks postmenstrual age (PMA), we monitored sleep–wake states using electroencephalography and behavior. We constructed survival models of sleep–wake bout durations and the effect of PMA and other factors, including stress (salivary cortisol), and examined whether sleep is resilient to nociceptive perturbations (a clinically necessary heel lance).

Results

Wake durations followed a heavy-tailed distribution as in adults and lengthened with PMA and stress. However, differently from adults, active sleep durations also had a heavy-tailed distribution, and with PMA, these shortened and became vulnerable to nociception-associated awakenings.

Conclusions

Sleep bouts are differently regulated in infants, with especially long active sleep durations that could consolidate this state’s maturational functions. Curtailment of sleep by stress and nociception may be disadvantageous, especially for preterm infants given the limited value of wakefulness at this age. This could be addressed by environmental interventions in the future.

Glucocorticoid receptor gene (NR3C1) methylation during the first thousand days: Environmental exposures and developmental outcomes

The first 1000 days from conception are a sensitive period for human development programming. During this period, environmental exposures may result in long-lasting epigenetic imprints that contribute to future developmental trajectories. The present review reports on the effects of adverse and protective environmental conditions occurring during the first 1000 days on glucocorticoid receptor gene (NR3C1) regulation in humans. Thirty-four studies were included. Wide variations emerged for biological tissues, number and position of analyzed CpG sites, and age at methylation and outcomes assessment. Increased NR3C1 methylation associated with first 1000 days stress exposures. Maternal caregiving behaviors significantly buffered precocious stress exposures. A less robust pattern of findings emerged for the association of NR3C1 methylation with physical health, neurobehavioral and neuroendocrine outcomes. Although drawing comprehensive conclusions is partially hindered by methodological limitations, the present review underlines the relevance of the first 1000 days from conception as a time window for developmental plasticity. Prospective cohort studies and epigenome-wide approaches may increase our understanding of dynamics epigenetic changes and their consequences for child development.

Practical approaches to sedation and analgesia in the newborn

The prevention, assessment, and treatment of neonatal pain and agitation continues to challenge clinicians and researchers. Substantial progress has been made in the past three decades, but numerous outstanding questions remain. In this setting, clinicians must establish safe and compassionate standardized practices that consider available efficacy data, long-term outcomes, and research gaps. Novel approaches with limited data must be carefully considered against historic standards of care with robust data suggesting limited benefit and clear adverse effects. This review summarizes available evidence while suggesting practical clinical approaches to pain assessment and avoidance, procedural analgesia, postoperative analgesia, sedation during mechanical ventilation and therapeutic hypothermia, and the issues of tolerance and withdrawal. Further research in all areas represents an urgent priority for optimal neonatal care. In the meantime, synthesis of available data offers clinicians challenging choices as they balance benefit and risk in vulnerable critically ill neonates.

A preliminary study of gut microbiome variation and HPA axis reactivity in healthy infants

The Hypothalamic Pituitary Adrenal (HPA) axis regulates hormonal responses to stress in both humans and animals and is dysregulated in a wide range of psychiatric disorders. There is strong evidence from rodent studies that gut microbial composition influences HPA axis development. In humans, variation in the gut microbiome has been associated with several psychological domains including depression and cognitive development, but studies focused on HPA axis development are still lacking. We tested whether differences in microbial composition are associated with HPA axis reactivity in a pilot study of 34 healthy human infants. HPA axis reactivity was assessed by measuring salivary cortisol in samples taken both before and after a heel stick, and 16S rRNA amplicon sequencing was used for identification and relative quantification of bacterial taxa. Subjects' alpha diversity levels showed a moderate positive association with their cortisol reactivity at one month of age. Exploratory genus-level analyses suggest that Staphylococcus, Prevotella, and genera in the order Lachnospiraceae may be related to cortisol reactivity at one month as well. The current study gives support for the endocrine pathway as a potential mediator in the microbiome-gut-brain axis during infancy, and as such provides motivation for future clinical work to support the development of stress-response systems through the manipulation of gut microbes.

Dehydroepiandrosterone at birth: Response to stress and relation to demographic, pregnancy and delivery factors

Enhanced production of dehydroepiandrosterone (DHEA) by the foetal hypothalamic-pituitary-adrenal (HPA) axis enables maturational events critical for labour induction and neonatal adaptation. Despite knowledge of the interconnected nature of maternal and foetal physiology and dramatic changes in DHEA production after birth, few studies have examined DHEA levels in newborns and none have examined DHEA's response to acute stress. Understanding normative patterns of early DHEA activity is needed to accurately assess functioning of the biological stress system with relevance for health and development. The present study analysed DHEA concentrations and change after stress among 93 newborns and associations with pregnancy, delivery and demographic risk factors. Three saliva samples, collected prior to and following a blood draw stressor, were used to determine baseline and stress reactive DHEA levels. Mothers self-reported on health behaviours during pregnancy. Data on obstetric factors were obtained from medical records. DHEA levels declined from pre- to post-stressor assessments. Results also showed that post-stressor DHEA change was significantly associated with administration of medications used to treat pain and accelerate labour. However, there was no significant variation in DHEA pre-stress levels or change after stress as a function of time after birth. By capturing DHEA levels after birth, the present study provides a window into prenatal health of the HPA system. The study also advances knowledge of DHEA in newborns by providing data on reference levels and important covariates. This information on basic adrenal physiology provides a foundation that can be expanded on to enhance understanding of early hypothalamic-pituitary-adrenal axis activity.

The impact of parental contact upon cortical noxious-related activity in human neonates

BACKGROUND

Neonates display strong behavioural, physiological and cortical responses to tissue-damaging procedures. Parental contact can successfully regulate general behavioural and physiological reactivity of the infant, but it is not known whether it can influence noxious-related activity in the brain. Brain activity is highly dependent upon maternal presence in animal models, and therefore this could be an important contextual factor in human infant pain-related brain activity.

METHODS

Global topographic analysis was used to identify the presence and inter-group differences in noxious-related activity in three separate parental contexts. EEG was recorded during a clinically required heel lance in three age and sex-matched groups of neonates (a) while held by a parent in skin-to-skin (n = 9), (b) while held by a parent with clothing (n = 9) or (c) not held at all, but in individualized care (n = 9).

RESULTS

The lance elicited a sequence of 4-5 event-related potentials (ERPs), including the noxious ERP (nERP), which was smallest for infants held skin-to-skin and largest for infants held with clothing (p=0.016). The nERP was then followed by additional and divergent long-latency ERPs (> 750 ms post-lance), not previously described, in each of the groups, suggesting the engagement of different higher level cortical processes depending on parental contact.

CONCLUSIONS

These results show the importance of considering contextual factors in determining infant brain activity and reveal the powerful influence of parental contact upon noxious-related activity across the developing human brain.

SIGNIFICANCE

This observational study found that the way in which the neonatal brain processes a noxious stimulus is altered by the type of contact the infant has with their mother. Specifically, being held in skin-to-skin reduces the magnitude of noxious-related cortical activity. This work has also shown that different neural mechanisms are engaged depending on the mother/infant context, suggesting maternal contact can change how a baby's brain processes a noxious stimulus.

A Nursing Perspective on Infant Bed-Sharing Using Multidisciplinary Theory Integration

The American Academy of Pediatrics recommends against bed-sharing between infants and caregivers due to an association with suffocation. Caregivers continue to share a bed with their infant despite these recommendations for a multitude of reasons. A close examination of the bed-sharing literature reveals that the debate is fundamentally about theoretical differences. The major theories used to frame this problem include the triple risk model of bed-sharing and evolutionary theories. Nurses are masters of multidisciplinary collaboration and are well positioned to unify the triple risk and evolutionary views of infant bed-sharing to guide future innovations in health care practice and research.

Examining the role of socioeconomic status and temperament in the hair cortisol levels of infants

Socioeconomic status (SES) appears to be an important contextual factor in children's developmental outcomes, including their responses to stress. However, some children are more susceptible to its effects than others. Hair cortisol is a newer method of assessing the activity of the HPA axis, providing cumulative cortisol levels. The present article examined whether temperament (negative emotionality) moderates the association between an SES index and the hair cortisol concentration (HCC) of infants. Sixty infants from 6 to 15 months of age were recruited, of which 49 had sufficient hair for cortisol analysis. The SES index was calculated from the education levels of the mothers, family income, and a scale measuring the quality of the home environment. Negative emotionality was measured with the three sub-scales of the Infant Behavior Questionnaire (falling reactivity, distress to limitations, and fear). Among infants low in negative emotionality, there was no association between SES and cortisol. In contrast, among those high in negative emotionality, a significant association was obtained. These infants showed lower levels of HCC in lower-SES environments. The findings suggest that there are individual differences in reacting to the environment, and low levels of cortisol (not high) were found in susceptible infants in lower-SES families.

Reference values for salivary cortisol in healthy young infants by liquid chromatography-tandem mass spectrometry

BACKGROUND

Sampling of salivary cortisol is non-invasive and important for the evaluation of the hypothalamic-pituitary-adrenal axis function and stress levels. However, the reference values for salivary cortisol measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in healthy infants are unclear. The aim of this study was to establish the reference values for salivary cortisol levels in healthy infants.

METHODS

This study was a prospective observational cohort study following the participants until the age of 6 months. We analyzed 71 healthy, full-term infants at age 1 month between December 2017 and March 2018. We repeated saliva sampling every month, measured the salivary cortisol levels in the early morning by LC-MS/MS, and took the subjects' medical history by questionnaire.

RESULTS

The minimum, 25th, 50th, 75th percentile, and maximum salivary cortisol levels were 0.08, 1.11, 2.21, 5.18, and 30.35 nmol/L, respectively.

CONCLUSIONS

We established the reference values for salivary cortisol in young infants using LC-MS/MS.

Infant emotional responses to challenge predict empathic behavior in toddlerhood

Although emotional responses are theorized to be important in the development of empathy, findings regarding the prediction of early empathic behavior by infant behavioral and physiological responses are mixed. This study examined whether behavioral and physiological responses to mild emotional challenge (still face paradigm and car seat task) in 118 infants at age 6 months predicted empathic distress and empathic concern in response to an empathy-evoking task (i.e, experimenter's distress simulation) at age 20 months. Correlation analyses, corrected for sex and baseline levels of physiological arousal, showed that stronger physiological and behavioral responses to emotional challenge at age 6 months were positively related to observed empathic distress, but not empathic concern, at age 20 months. Linear regression analyses indicated that physiological and behavioral responses to challenge at 6 months independently predicted empathic distress at 20 months, which suggests an important role for both physiological and behavioral emotional responses in empathy development. In addition, curvilinear regression analyses showed quadratic associations between behavioral responses at 6 months, and empathic distress and empathic concern at 20 months, which indicates that moderate levels of behavioral responsivity predict the highest levels of empathic distress and empathic concern.

Relationship between heat stress exposure and some immunological parameters among foundry workers

Occupational exposure to heat stress may lead to changes in blood cell count. The objective of this retrospective descriptive-analytical field study is to investigate the relationship between heat stress exposure and some immunological parameters among foundry workers. This study was carried out on 55 subjects of which, 35 were working in a foundry unit (exposed group) and 20 were working in a computer numerical control (CNC) machining unit (control group). The measurement method consisted of taking 10 cc of the subjects' blood between 10 am and 2 pm and then performing the automated blood cell counting and enzyme-linked immunosorbent assay (ELISA) on the sample. Environmental parameters such as noise levels, lighting, and the wet-bulb globe temperature (WBGT) index were measured at the subjects' workstations. All measurements were made in the first half of the month of July. The mean WBGT index was 22.5 ± 2.16 °C for the control group and 32.97 ± 3.22 °C for the exposed group. The laboratory test results show a significant decrease in white blood cell count and lymphocyte levels and a significant increase in neutrophil levels and neutrophil to lymphocyte ratio in exposed group compared with control ones (P < 0.05). IgM levels decrease under heat stress, but we do not observe significant differences between IgG and IgA levels between two groups. A significant negative correlation was observed between white blood cell count, lymphocyte levels, and IgM concentration with WBGT index and significant positive correlation was observed between neutrophil and neutrophil to lymphocyte ratio with WBGT index. No significant correlation was observed between sound pressure levels and light intensity with studied immunological parameters. In conclusion, under heat stress conditions, leukocytes levels and immunoglobulin concentration may reduce and it may weaken and suppress the human immune system.

Salivary cortisol reactivity to psychological stressors in infancy: A meta-analysis

Measurement of salivary cortisol is a practical and non-invasive tool for studying stress reactivity to various types of stressors even in young infants. Whereas studies using physical stressors during the first months of life have found robust cortisol responses to painful stimuli, research with older infants using psychological stressors (e.g., parental separation) has produced mixed findings, limiting our understanding of potential developmental changes in cortisol reactivity across infancy. In the present study, we used meta-analysis to systematically investigate whether psychological stressor paradigms are associated with measurable cortisol responses in infants under 18 months of age and whether the magnitude of the responses is moderated by the type of psychological stressor (i.e., separation, frustration, novelty, or disruption of parental interaction), infant age, and other potential moderators. Across 47 studies (N = 4095, age range: 3-18 months), we found that commonly used psychological stressor paradigms are associated with a small (Hedges' g = .11) increase in salivary cortisol levels in typically developing infants. Stressor type moderated the effect sizes, and when effect sizes in each category were analyzed separately, only the separation studies were associated with a consistent increase in cortisol following the stressor. Age did not moderate the effect sizes either in the full set of studies or within the separate stressor types. These meta-analytic results indicate that the normative cortisol response to psychological stressors across infancy is small and emphasize the need for standardized stressor paradigms to assess cortisol responses systematically across infancy.

Stress during pregnancy affected neonatal outcomes and changed cortisol and leptin levels both in mothers and newborns

BACKGROUND

The present study aimed to determine the effect of perceived stress during pregnancy on neonatal outcomes and cortisol and leptin levels in mothers and their newborns.

METHODS

This longitudinal study was carried out on 110 pregnant women in Miandoab city, Iran. Mothers, who had singleton pregnancies and gestational age of 24 to 28 weeks, were included in the study. The participants were asked to fill out Cohen's Perceived Stress Scale (PSS). The mothers were then tracked in gestational ages of 28-32 weeks, 32-36 weeks, and the time of delivery. The maternal and umbilical cord blood samples were obtained during labor in order to measure leptin and cortisol levels.

RESULTS

Umbilical cortisol level was significantly higher in newborns who had meconium stained amniotic fluid than those who did not. Maternal blood leptin levels at delivery were significantly higher in the mothers whose neonates had respiratory distress, low birth weight, low head circumference, low Apgar score, and were premature than those whose neonates did not have such problems. The level of leptin in umbilical cord blood was significantly higher in neonates who had respiratory distress than those who did not. The results also showed a significant correlation between maternal cortisol levels and PSS during weeks 24-28 and the entire pregnancy. A significant relationship was observed between umbilical leptin and maternal leptin levels.

CONCLUSIONS

It can be concluded that stress during pregnancy is accompanied by fetal distress. The probable reason for newborns distress may be related to increased maternal leptin levels.

The influence of pain, agitation, and their management on the immature brain

Preterm infants are exposed to frequent painful procedures and agitating stimuli over the many weeks of their hospitalization in the neonatal intensive care unit (NICU). The adverse neurobiological impact of pain and stress in the preterm infant has been well documented, including neuroimaging and neurobehavioral outcomes. Although many tools have been validated to assess acute pain, few methods are available to assess chronic pain or agitation (a clinical manifestation of neonatal stress). Both nonpharmacologic and pharmacologic approaches are used to reduce the negative impact of pain and agitation in the preterm infant, with concerns emerging over the adverse effects of analgesia and sedatives. Considering benefits and risks of available treatments, units must develop a stepwise algorithm to prevent, assess, and treat pain. Nonpharmacologic interventions should be consistently utilized prior to mild to moderately painful procedures. Sucrose may be utilized judiciously as an adjunctive therapy for minor painful procedures. Rapidly acting opioids (fentanyl or remifentanil) form the backbone of analgesia for moderately painful procedures. Chronic sedation during invasive mechanical ventilation represents an ongoing challenge; appropriate containment and an optimal environment should be standard; when indicated, low-dose morphine infusion may be utilized cautiously and dexmedetomidine infusion may be considered as an emerging adjunct.

The development of the hypothalamus-pituitary-adrenal axis during infancy may be affected by antenatal glucocorticoid therapy

BACKGROUND

Developmental changes in the hypothalamus-pituitary-adrenal (HPA) axis during infancy have been reported in term infants, but those in preterm infants have yet to be elucidated. If developmental changes in the HPA axis of preterm infants are modulated by any factors, it may affect their future health. Few studies have examined the lasting consequences of antenatal glucocorticoids on the development of the HPA axis.

METHODS

We measured pre- and post-palivizumab vaccination salivary cortisol values in two conforming periods of three-months intervals during infancy, and compared cortisol values and the response of cortisol secretion between groups with and without antenatal glucocorticoid (AG) therapy.

RESULTS

Although the strength of the response of cortisol secretion to palivizumab fell age-dependently (until late infancy) in the Non-AG group, the opposite pattern was exhibited in the AG group. The changes of the delta cortisol values between the 2 groups were significant.

CONCLUSIONS

This study suggests that the HPA axis of preterm infants whose mothers receive AG therapy may be upregulated during infancy, possibly leading to long lasting health problems.

Child depressive symptoms: Associations with salivary cortisol and alpha amylase in two distinct challenges

Child depression has been inconsistency linked to cortisol and salivary alpha-amylase (sAA) reactivity. This study assessed three factors that contribute to inconsistencies: 1) the differential effectiveness of laboratory challenges to elicit cortisol and sAA; 2) the impact of cortisol-sAA coordination; and 3) variation in parent versus child ratings of depression. A community sample of 52 children participated in the Trier Social Stress Test-Child Version (TSST-C) and a competition challenge. Saliva was collected and assayed for cortisol and sAA. Analyses were conducted using multilevel modeling. Child-reported depressive symptoms were associated with a declining cortisol trajectory in the TSST-C. Mother-reported depressive symptoms were associated with higher baseline sAA in the TSST-C and the competition challenge. Further, child-reported depressive symptoms were associated with cortisol-sAA coordination in the competition challenge. Findings underscore the nature of the challenge and the behavioral informant as impacting associations between child depressive symptoms and cortisol and sAA secretion.

Is one secure attachment enough? Infant cortisol reactivity and the security of infant-mother and infant-father attachments at the end of the first year

Attachment security is theorized to shape stress reactivity, but extant work has failed to find consistent links between attachment security to mothers and infant cortisol reactivity. We examined family configurations of infant-mother and infant-father attachment security in relation to infant cortisol reactivity. One-year old infants (N = 180) participated in the Strange Situation with mothers and fathers in two counterbalanced lab visits, one month apart (12 and 13 months). Infants with secure attachments only to their fathers and not their mothers had higher cortisol levels than infants with a secure attachment to mother and also exhibited a blunted cortisol response (high at baseline and then a decrease after stress). Results suggest that a secure attachment to father may not be enough to reduce infant stress reactivity when the infant-mother attachment is insecure, and future research is needed to uncover the family dynamics that underlie different family configurations of attachment security.

Emotional Stress During Pregnancy - Associations With Maternal Anxiety Disorders, Infant Cortisol Reactivity, and Mother-Child Interaction at Pre-school Age

There is growing evidence that even milder forms of maternal stress or anxiety during pregnancy affect the fetus causing possible long-term consequences for infant and child development. The mechanisms through which prenatal maternal stress may affect the unborn are not yet entirely clarified. Due to limited self-regulatory skills after birth, infants depend on sensitive behavior of their parents to regulate affective states and physiological arousal. Dyadic affect regulation has been linked to various developmental patterns up to adolescence and thereby represents a key element of early social relationships. Aim of the study was to evaluate possible long-term consequences of emotional stress during pregnancy and postpartum anxiety disorders, as well as infant postpartum cortisol reactivity on mother–child-interaction at pre-school age. The sample comprised of N = 63 mother–infant dyads at study entry, n = 28 diagnosed with postpartum anxiety disorders according to the Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV), n = 35 were healthy controls. Mothers were interviewed with the Structured Clinical Interview for DSM-IV Disorders at an average infant age of M = 4.1 months and filled out a questionnaire regarding emotional stress during pregnancy. Further, they were videotaped during the Face-to-Face-Still-Face paradigm (FFSF), a widely used mild socio-emotional stressor for infants. To determine infant stress-reactivity, infant salivary cortisol was collected before, immediately after and 20 min after the FFSF. Missing values were estimated by multiple imputations. At the age of M = 5.3 years, mother-child-interaction was re-assessed in a follow-up sample of n = 30 dyads via a free-play situation. Moreover, dimensional measures for anxiety were assessed. Mothers in the clinical group reported significantly higher stress scores than the control group. Infant stress reactivity in the early postpartum period and maternal anxiety symptoms at the 5-year follow-up assessment were significantly associated with dyadic interaction quality at pre-school age. Even though maternal stress during pregnancy did not directly predict mother–child interaction quality at pre-school age, it was significantly correlated with infant cortisol reactivity during postpartum period. Nevertheless, caution should be taken when interpreting the results considering the small sample size.