Examining change in cortisol patterns during the 10-week transition to a new child-care setting

Do toddlers' levels of cortisol and the perceptions of parents and professional caregivers tell the same story about transition from home to childcare? A mixed method study

Introduction

Enrolling in childcare represents the first transition in toddlers' lives and lays the foundation for their well-being in childcare centers going forward. Child cortisol levels may be an indicator of how toddlers themselves experience their introduction to childcare. In the present study, we explored changes in toddler cortisol levels during their first month in childcare and at a 3-month follow-up, as well as the perceptions of parents and professional caregivers regarding the toddlers' settling-in process during the same period.

Method

This study used a mixed-method design. Saliva samples were collected from 113 toddlers and their cortisol levels analyzed. Qualitative notes were collected from parents (n = 87) and professional caregivers (n = 101). The data were analyzed using linear mixed model and thematic analyses, respectively.

Results

Changes in toddler cortisol levels and their parents' and professional caregivers' perceptions of the transition process fit well. Both data sources indicated an easy start in childcare when parents were present, while the first weeks separated from parents seemed quite demanding. After 3 months, the cortisol levels returned to a low level, while child well-being was perceived as high.

Discussion

Toddlers need time to adapt to childcare settings. Even if they are well taken care of by their keyworkers during the day, many toddlers are tired and exhausted in the evenings at home, particularly in the first weeks of separation from their parents. Both professional caregivers and parents should be aware of toddlers' need for emotional support during their transition to childcare.

Transition to Preschool: Paving the Way for Preschool Teacher and Family Relationship-Building

Background

Previous research suggests that interactions between preschool teachers and children in early care and educational contexts can contribute to the child's positive attachment development and socioemotional adjustment.

Objective

Investigate how the transition process to preschool is organized and whether various ways of organizing it may differently influence family-teacher relationship-building and child adjustment.

Methods

Conducted a mixed methods study of quantitative and qualitative survey data from Swedish preschool professionals (N = 535).

Results

Preschool introduction varied across preschools in several structural aspects such as introduction length and intensity, timing for first child-parent separation, and number of children and teachers involved in the introduction process. Results moreover suggested that different introduction models were associated with different ways of engaging the parent, where the "parent-active" model was characterized by a high level of parental participation during the introductory activities. This was perceived by preschool professionals as positively influencing the family-teacher relational formation.

Conclusion

Findings suggest that inviting parents to participate actively in preschool transition may help better engage them in the introduction process, which in turn may positively influence family-teacher relationship-building. Future research should focus in more detail on how child-teacher and parent-teacher interactions, respectively, influence family-teacher relationship-building and child adjustment during, and after, the introduction period.

Psychophysiological adjustment to formal education varies as a function of peer status and socioeconomic status in children beginning kindergarten

The transition to kindergarten can be stressful as children adjust to novel separations from their caregivers and become accustomed to their peer group. A 9-month study of 96 children (M_age  = 5.37 years, SD = 0.42) from Barranquilla, Colombia, assessed socioeconomic differences in hypothalamic-pituitary-adrenal (HPA) axis functioning across the kindergarten year. Children were from four different classrooms in one school. Saliva samples were collected twice a day across 3 consecutive days at the beginning and end of the school year. We examined whether change in HPA axis activation across the year varied as a function of a child's socioeconomic status (SES) and experience in the peer group. We found that rejected children and lower SES children had lower cortisol levels early in the morning. Rejected children had a flatter morning cortisol slope. Lower SES children had higher cortisol than their higher SES peers at the end of the school year and a flatter morning cortisol slope. Taken together, these findings suggest that diurnal cortisol in children beginning kindergarten may be influenced by both peer rejection and SES.

Child Care in Times of COVID-19: Predictors of Distress in Dutch Children and Parents When Re-entering Center-Based Child Care After a 2-Month Lockdown

As a consequence of the outbreak of the Coronavirus Disease 2019 (COVID-19) child care facilities all over the world were temporarily closed to minimize the spread of the virus. In Netherlands, the first closure lasted for almost 2 months. The return to the child care center after this significant interruption was expected to be challenging, because earlier studies demonstrated that transitions into child care can be stressful for both children and their parents. The current paper retrospectively examined the distress of Dutch children (aged 0-4) and their parents during the first 2 weeks after the reopening of child care centers, and what factors accounted for individual differences in distress. In total, 694 parents filled out an online questionnaire about stress during closure and distress after the reopening of child care centers. Furthermore, questions regarding several demographic variables and child care characteristics were included, as well as questionnaires measuring child temperament, parental separation anxiety, and parental perception of the child care quality. Results showed that younger children and children with parents scoring higher on separation anxiety experienced more distress after the reopening, as reported by parents. Furthermore, children were more distressed upon return when they attended the child care center for less hours per week after the reopening, experienced less stress during closure, and grew up in a one-parent family. With regard to parental distress after the reopening, we found that parents scoring higher on separation anxiety and fear of COVID-19 experienced more distress. Moreover, parents experiencing less stress during closure and mothers were more distressed when the child returned to the child care center. Finally, concurrent child and parental distress after reopening were positively related. The results of the current study may help professional caregivers to identify which children and parents benefit from extra support when children return to the child care center after an interruption. Especially the role that parental separation anxiety played in predicting both child and parental distress deserves attention. More research is required in order to study the underlying mechanisms of these associations and to design appropriate interventions.

Infants' stress responses and protest behaviors at childcare entry and the role of care providers

During the transition from home to childcare, 70 15-month-old infants were videotaped, and their negative emotions were rated. Infants' attachments to mothers were assessed prior to child care entry and to care providers five months later using the Strange Situation Procedure (SSP). Infant heart rate was monitored at home, during adaptation to childcare (mothers present), and during subsequent separations. Respiratory sinus arrhythmia (RSA) was computed from the beat-to-beat measures of heart rate to reflect vagal tone, which is reduced during chronic states of stress, and was collected upon Arrival, during in-group Play, and when in the Group more generally. All infants responded to childcare entry with low RSA levels indicating stress. However, during adaptation with the mother present, RSA was higher for securely attached infants. On the first separation day, 35.3% of the infants fussed and cried extensively. These intense protests predicted later secure attachments to care providers, which adaptively helped to reduce stress, especially in infants who protested extensively, as if summoning their mothers back. Because extensive protest suggests limited regulatory capacities, infants risk overburdening the stress system when left unsupported.

Developmental pathways from preschool irritability to multifinality in early adolescence: the role of diurnal cortisol

BACKGROUND

Early irritability predicts a broad spectrum of psychopathology spanning both internalizing and externalizing disorders, rather than any particular disorder or group of disorders (i.e. multifinality). Very few studies, however, have examined the developmental mechanisms by which it leads to such phenotypically diverse outcomes. We examined whether variation in the diurnal pattern of cortisol moderates developmental pathways between preschool irritability and the subsequent emergence of internalizing and externalizing symptoms 9 years later.

METHOD

When children were 3 years old, mothers were interviewed about children's irritability and completed questionnaires about their children's psychopathology. Six years later, children collected saliva samples at wake-up and bedtime on three consecutive days. Diurnal cortisol patterns were modeled as latent difference scores between evening and morning samples. When children were approximately 12 years old, mothers again completed questionnaires about their children's psychopathology.

RESULTS

Among children with higher levels of irritability at age 3, a steeper diurnal cortisol slope at age 9 predicted greater internalizing symptoms and irritability at age 12, whereas a blunted slope at age 9 predicted greater externalizing symptoms at age 12, adjusting for baseline and concurrent symptoms.

CONCLUSION

Our results suggest that variation in stress system functioning can predict and differentiate developmental trajectories of early irritability that are relatively more internalizing v. those in which externalizing symptoms dominate in pre-adolescence.

Addressing educational inequalities and promoting learning through studies of stress physiology in elementary school students

To be ready to learn, children need to be focused, engaged, and able to bounce back from setbacks. However, many children come to school with heightened or diminished physiological arousal due to exposure to poverty-related risks. While stress physiology plays a role in explaining how adversity relates to processes that support students' cognitive development, there is a lack of studies of physiological stress response in educational settings. This review integrates relevant studies and offers future directions for research on the role of stress physiology in the school adaptation of elementary school students, focusing on these important questions: (a) What are the links between physiological stress response and learning-related skills and behaviors, and do they vary as a function of proximal and distal experiences outside of school? (b) How are school experiences associated with students' physiological stress response and related cognitive and behavioral adaptations? (c) How can we leverage measures of students' physiological stress response in evaluations of school-based interventions to better support the school success of every student? We hope to stimulate a new wave of research that will advance the science of developmental stress physiology, as well as improve the application of these findings in educational policy and practice.

Deconstructing Cumulative Risk: Poverty and Aspects of Instability Relate Uniquely to Young Children's Basal Cortisol

This study deconstructs cumulative risk to probe unique relations to basal cortisol for family income and four distinct aspects of poverty-related instability. Participants were 288 children aged 3-5 years who attended Head Start preschool. Parents reported on poverty risks. Children provided samples of salivary cortisol at four times of day on 6 days. Results of hierarchical linear modeling with piecewise latent growth curves representing basal cortisol indicated unique relations for family income, household chaos, neighborhood risk, attachment-disruptive residential changes, and non-attachment changes. The findings support an equifinality implied by cumulative risk models in demonstrating that multiple risks relate to cortisol dysregulation yet also suggest the utility of considering unique effects of different risks for neurophysiological stress response functioning.

Latent Change Score Models for the Study of Development and Dynamics in Organizational Research

The empirical study of change has proven to be one of the most vexing challenges in organizational science. Fortunately, contemporary methodologies originating from developmental psychology may provide a potential solution and are consequently working their way into the literature. In particular, organizational researchers are increasingly employing variations of latent change score (LCS) models to address questions regarding change, development, and dynamics. Although these models may indeed be used to reliably study change, development, and dynamics, many studies utilizing these models—and published in premier outlets—are characterized by questionable methodological choices, improper modeling procedures, and suboptimal research designs. Thus, the purpose of the present article is to (a) provide a critical review of LCS models, (b) outline appropriate modeling procedures (with corresponding Mplus and R syntax), (c) compare and contrast LCS modeling with other analytical techniques, and (d) delineate best practices. Ultimately, we endorse the use of LCS models by organizational researchers interested in studying longitudinal phenomena. However, we also heed researchers to do so judiciously because their misuse may lead to their unwarranted rejection by the field.

Toddlers' diurnal cortisol levels affected by out-of-home, center-based childcare and at-home, guardian-supervised childcare: comparison between different caregiving contexts

Previous research suggests that attending non-parental out-of-home childcare is associated with elevated cortisol levels for some children. We aimed to compare diurnal saliva cortisol levels between children having out-of-home, center-based childcare or those having at-home, guardian-supervised childcare in Finland. A total of 213 children, aged 2.1 years (SD = 0.6), were drawn from the ongoing Finnish birth cohort study. Saliva samples were collected over 2 consecutive days (Sunday and Monday), with four samples drawn during each day: 30 min after waking up in the morning, at 10 am, between 2 and 3 pm, and in the evening before sleep. These results suggest that the shapes of the diurnal cortisol profiles were similar in both childcare groups following a typical circadian rhythm. However, the overall cortisol levels were on average 30% higher (95% CI: [9%, 54%], p = .004) with the at-home childcare in comparison with the out-of-home childcare group. Furthermore, a slight increase in the diurnal cortisol pattern was noticed in both groups and in both measurement days during the afternoon. This increase was 27% higher ([2%, 57%], p = .031) in the out-of-home childcare group during the out-of-home childcare day in comparison with the at-home childcare day. The elevated afternoon cortisol levels were partly explained by the afternoon naps, but there were probably other factors as well producing the cortisol rise during the afternoon hours. Further research is needed to define how a child's individual characteristic as well as their environmental factors associate with cortisol secretion patterns in different caregiving contexts.

Associations of childcare type, age at start, and intensity with body mass index trajectories from 10 to 42 years of age in the 1970 British Cohort Study

BACKGROUND

Attending childcare is related to greater childhood obesity risk, but there are few long-term follow-up studies. We aimed to examine the associations of childcare type, age at start, and intensity with body mass index body mass index (BMI) trajectories from ages 10 to 42 years.

METHODS

The sample comprised 8234 individuals in the 1970 British Cohort Study, who had data on childcare attendance (no, yes), type (formal, informal), age at start (4-5, 3-3.99, 0-2.99 years old), and intensity (1, 2, 3, 4-5 days/week) reported at age 5 years and 32 563 BMI observations. Multilevel linear spline models were used to estimate the association of each exposure with the sample-average BMI trajectory, with covariate adjustment. A combined age at start and intensity exposure was also examined.

RESULTS

Attending vs not attending and the type of childcare (none vs formal/informal) were not strongly related to BMI trajectories. Among participants who attended childcare 1 to 2 days a week, those who started when 3 to 3.99 years old had a 0.197 (-0.004, 0.399) kg/m² higher BMI at age 10 years than those who started when 4 to 5 years old, and those who started when 0 to 2.99 years old had a 0.289 (0.049, 0.529) kg/m² higher BMI. A similar dose-response pattern for intensity was observed when holding age at start constant. By age 42 years, individuals who started childcare at age 0 to 2.99 years and attended 3 to 5 days/week had a 1.356 kg/m² (0.637, 2.075) higher BMI than individuals who started at age 4 to 5 years and attended 1 to 2 days/week.

CONCLUSIONS

Children who start childcare earlier and/or attend more frequently may have greater long-term obesity risk.

Perceived Barriers to Fruit and Vegetable Gardens in Early Years Settings in England: Results from a Cross-Sectional Survey of Nurseries

Garden-based interventions may increase child intake of fruits and vegetables and offset food costs, but few have been conducted in early care and education (ECE). This study assessed whether nurseries were interested in and perceived any barriers to growing fruits and vegetables. Surveys were mailed to a cross-sectional sample of nurseries in 2012–2013 throughout England. Nurseries were stratified based on socioeconomic status as most, middle, or least deprived areas. We fit logistic regression models to assess the odds of nurseries interested in growing fruits and vegetables and perceiving any barriers, by deprivation tertile. A total of 851 surveys were returned (54% response). Most nurseries (81%) were interested in growing fruits and vegetables. After adjustment, there was no difference in interest in the middle (OR 1.55; CI 0.84, 2.78; p = 0.16) or most (OR 1.05; CI 0.62, 1.78; p = 0.87) deprived areas, compared to the least deprived. Nurseries reported barriers to growing fruits and vegetables, including space (42%), expertise (26%), and time (16%). Those in the most deprived areas were more likely to report space as a barrier (OR 2.02; 95% CI 1.12, 3.66; p = 0.02). Nurseries in the most deprived areas may need creative solutions for growing fruits and vegetables in small spaces.

Childhood otitis media: Relationship with daycare attendance, harsh parenting, and maternal mental health

Psychological stress has been linked to developmental problems and poor health in children, but it is unclear whether it is also related to otitis media (OM). As part of a long-term study surveying the characteristics of childcare and development in Taiwan, we analyzed the relationship between OM and sources of psychological stress in children, such as poor maternal mental health and harsh parental discipline. We analyzed the data of 1998 children from the "Kids in Taiwan: National Longitudinal Study of Child Development & Care (KIT) Project" at the age of 3 years. Using bivariate and multivariate logistic regression models, we tested several risk factors as potential independent predictors of two outcomes: parent-reported incidence of OM and child health. The proportion of children who had developed OM in the first 3 years of their life was 12.5%. Daycare attendance (odds ratio [OR]: 1.475; 95% confidence interval [CI]: 1.063-2.046), poor maternal mental health (OR: 1.913; 95% CI: 1.315-2.784), and harsh parental discipline (OR: 1.091; 95% CI: 1.025-1.161) correlated with parent-reported occurrence of OM. These findings suggest that providing psychosocial support to both parents and children might be a novel strategy for preventing OM.

Children's cortisol response to the transition from preschool to formal schooling: A review

This review examines the current state of knowledge regarding children's biological stress response during the transition from preschool to compulsory formal schooling, focusing on longitudinal studies that include repeated measures of cortisol concentrations in saliva or scalp hair. In all, eight independent studies (ten publications) were found and their results support the hypothesis that the transition from preschool to formal schooling coincides with an increase in cortisol concentration in both saliva and hair. Evidence of recovery (i.e. decrease in stress response over time) is more limited and suggests that it could take as many as 3-6 months before kindergarten children's cortisol concentration returns to baseline levels. However, important individual differences are observed. Potential predictors that have received some empirical support include child temperament (fearfulness/inhibition or surgency/extroversion) and prenatal maternal stress or anxiety. Very few studies, however, have examined whether there are actual functional consequences of individual differences in children's cortisol response associated with this transition. Finally, current methodological limitations and avenues for future studies are discussed.

Homotypic and heterotypic continuity of internalizing and externalizing symptoms from ages 3 to 12: The moderating role of diurnal cortisol

Psychological symptoms that arise in early childhood can follow a multitude of patterns into adolescence, including homotypic continuity (i.e., similar symptoms over time) and heterotypic continuity (i.e., a shift in symptoms over time). However, we know very little about the factors that distinguish homotypic vs. heterotypic continuity of early internalizing and externalizing symptoms over development. In a separate line of research, diurnal cortisol has been shown to predict later internalizing and externalizing problems. In the current study, we tested whether diurnal cortisol patterns moderated the course of internalizing and externalizing symptoms from preschool to early adolescence. 554 children (54% male) and parents participated in a longitudinal study. Parents reported on their children's internalizing and externalizing symptoms at ages 3 and 12, and children collected diurnal saliva samples at age 9. Results showed that a steeper cortisol decline at age 9 combined with high internalizing or externalizing problems at age 3 predicted higher internalizing problems at age 12. A more blunted cortisol decline combined with early internalizing or externalizing problems predicted higher externalizing problems in early adolescence. These results illustrate the moderating role of stress system functioning in homotypic and heterotypic patterns of psychopathology from preschool to early adolescence.

Stability and change in daytime and nighttime sleep in children attending daycare

Many young children experience insufficient or poor quality sleep, which may have implications for adjustment and cognitive performance. This study tested group-level changes and rank-order stability in both daytime and nighttime sleep parameters over a six-month period, from fall to spring, among children receiving high-quality, center-based daycare. A total of 68 preschoolers (54% girls; Mage = 3.80 years, SD = .68) participated. Sleep was assessed via actigraphy for seven days and nights; sleep duration (actual sleep minutes) and quality parameters were derived. Analyses of group-level changes indicated that children’s daytime and nighttime sleep duration did not change significantly from fall to spring. Nighttime sleep quality showed significant improvement, however, such that children had higher sleep efficiency in the spring than in the fall. Rank-order stability in both nighttime and daytime measures of sleep duration and quality was moderate, and stability in daytime sleep quality was low. Results add to a sparse literature examining stability in sleep parameters in young children using actigraphy.

Sex differences in cortisol's regulation of affiliative behavior

A contribution to a special issue on Hormones and Human Competition. A stress perspective is used to illuminate how competitive defeat and victory shape biology and behavior. We report a field study examining how change in cortisol following perceived defeat (vs. victory) in a competition-in this case, a dog agility competition-relates to affiliative behavior. Following competition, we measured cortisol change and the extent to which dog handlers directed affiliative behaviors toward their dogs. We found striking sex differences in affiliation. First, men were more affiliative toward their dogs after victory, whereas women were more affiliative after defeat. Second, the greater a female competitor's increase in cortisol, the more time she spent affiliating with her dog, whereas for men, the pattern was the exact opposite: the greater a male competitor's increase in cortisol, the less time he spent affiliating with his dog. This pattern suggests that, in the wake of competition, men and women's affiliative behavior may serve different functions-shared celebration for men; shared consolation for women. These sex differences show not only that men and women react very differently to victory and defeat, but also that equivalent changes in cortisol across the sexes are associated with strikingly different behavioral consequences for men and women.

Transition to Kindergarten: Negative Associations between the Emotional Availability in Mother-Child Relationships and Elevated Cortisol Levels in Children with an Immigrant Background

Background: The transition to child care is a challenging time in a child's life and leads to elevated levels of cortisol. These elevations may be influenced by the quality of the mother-child relationship. However, remarkably little is known about cortisol production in response to the beginning of child care among children-at-risk such as children with an immigrant background. However, attending kindergarten or any other child day-care institution can for example have a compensating effect on potential language deficits thus improving the educational opportunities of these children. Method: Data of a subsample of N = 24 "hard-to-reach" mother-child dyads was collected in the context of the psychoanalytic early prevention project FIRST STEPS. The project focuses on the earliest integration of children with an immigrant background by supporting parenting capacities in the critical phase of migration and early parenthood. Children's hair cortisol concentration (HCC) was assessed 1 week before (mean age = 38.77 months) and 3 months after kindergarten entry (mean age = 42.26 months). Hair analysis was conducted for both times of measurement, reflecting the first 3 months after kindergarten entry and 3 months prior. Furthermore, the emotional quality of the mother-child relationship was assessed with the help of the Emotional Availability Scales (EAS; Biringen, 2008) shortly before kindergarten entry when the children were about 3 years old (mean age = 37.2). Results and Conclusion: Children's mean cumulated HCC was higher after kindergarten entry than before. The increase correlated negatively with several dimensions of the EAS. Repeated measures ANCOVA revealed that particularly responsive children and children who had experienced less intrusive mother-child relationships demonstrated lower elevations in HCC after kindergarten entry. Furthermore, a decreased EA score was found in all EA dimensions, besides the dimension "mother's non-hostility," indicating problematic EA within the mother-child relationships of the sample. The results suggest that children with an immigrant background who experience more emotional available mother-child relationships seem to regulate stress induced by kindergarten entry more effectively, indicated by lower cortisol elevations after entry. This implicates that supporting early mother-child relationships by intervention may have a positive effect on the children's ability to regulate stress induced by kindergarten entry thus promoting child development.

Social Buffering of Stress in Development: A Career Perspective

This review provides a broad overview of my research group's work on social buffering in human development in the context of the field. Much of the focus is on social buffering of the hypothalamic-pituitary-adrenocortical (HPA) system, one of the two major arms of the mammalian stress system. This focus reflects the centrality of the HPA system in research on social buffering in the fields of developmental psychobiology and developmental science. However, buffering of the cardiovascular and autonomic nervous system is also discussed. The central developmental question in this area derives from attachment theory, which argues that the infant's experience of stress and arousal regulation in the context of her early attachment relationships is not an immature form of social buffering experienced in adulthood but rather the foundation out of which individual differences in the capacity to gain stress relief from social partners emerges. The emergence of social buffering in infancy, changes in social buffering throughout childhood and adolescence, the influence of early experience on later individual differences in social buffering, and critical gaps in our knowledge are described.

Children's physiological responses to childcare

This review focuses on children's physiological responses to out-of-home childcare. The finding that children's cortisol levels are higher at childcare than at home has been well-replicated. Here we summarize recent evidence examining possible correlates of elevated cortisol levels. Reviewed studies suggest that childcare quality matters, whereas group sizes and type of care do not. As for child characteristics, elevated cortisol at childcare is more pronounced in toddlers than in infants, and in inhibited and aggressive children. We discuss recent advances focusing on hair cortisol analysis and immunomarkers of stress, and suggest that there is a need for experimental and longitudinal studies to examine causal relations and possible negative long-term consequences for children's health and development.

ALL OUR SONS: THE DEVELOPMENTAL NEUROBIOLOGY AND NEUROENDOCRINOLOGY OF BOYS AT RISK

Why are boys at risk? To address this question, I use the perspective of regulation theory to offer a model of the deeper psychoneurobiological mechanisms that underlie the vulnerability of the developing male. The central thesis of this work dictates that significant gender differences are seen between male and female social and emotional functions in the earliest stages of development, and that these result from not only differences in sex hormones and social experiences but also in rates of male and female brain maturation, specifically in the early developing right brain. I present interdisciplinary research which indicates that the stress-regulating circuits of the male brain mature more slowly than those of the female in the prenatal, perinatal, and postnatal critical periods, and that this differential structural maturation is reflected in normal gender differences in right-brain attachment functions. Due to this maturational delay, developing males also are more vulnerable over a longer period of time to stressors in the social environment (attachment trauma) and toxins in the physical environment (endocrine disruptors) that negatively impact right-brain development. In terms of differences in gender-related psychopathology, I describe the early developmental neuroendocrinological and neurobiological mechanisms that are involved in the increased vulnerability of males to autism, early onset schizophrenia, attention deficit hyperactivity disorder, and conduct disorders as well as the epigenetic mechanisms that can account for the recent widespread increase of these disorders in U.S. culture. I also offer a clinical formulation of early assessments of boys at risk, discuss the impact of early childcare on male psychopathogenesis, and end with a neurobiological model of optimal adult male socioemotional functions.

Salivary cortisol and cognitive development in infants from low-income communities

Early stress exposure is proposed to have significant lasting effects on cognitive development. The glucocorticoid hormone cortisol, a product of the hypothalamic-pituitary-adrenal (HPA) axis, is a particular focus of research, however, the majority of past research has been based on studies of older children and adults. Evidence linking cortisol levels in infancy with cognitive development is lacking. In a large cohort sample of infants (N = 1091) oversampled for psychosocial risk, we tested whether basal cortisol levels and cortisol reactivity to emotional stressors administered at 7 and 15 months of age were associated with cognitive development measured at 15 months. Cognitive development was measured using the Mental Development Index of the Bayley Scales of Infant Development. Multiple regression analyses indicated that basal cortisol levels at 15 months, and to a lesser extent at seven months, were inversely associated with infant cognitive development after adjusting for psychosocial and obstetric risk. The findings provide some of the first evidence that HPA axis activity in infancy is associated with early cognitive development.

The relationship between childcare and adiposity, body mass and obesity-related risk factors: protocol for a systematic review of longitudinal studies

BACKGROUND

The rising prevalence of obesity, particularly in childhood, is a global public health emergency. There is some evidence that exposure to non-parental childcare before age 6 years is associated with subsequent development of obesity and obesity-related behaviours such as physical activity, sedentary behaviour, sleep, diet and stress, although these findings are inconsistent. It is possible that the relationship between early childcare and later obesity and obesity-related behaviours depends on characteristics of childcare exposure such as type (i.e. informal versus formal care), duration (i.e. number of years spent in childcare), intensity (e.g. number of hours per week) and timing (i.e. age of onset of childcare) of care received. The relationship may also be moderated by socio-demographic characteristics of children and their families. We will conduct a systematic review exploring longitudinal associations between childcare (type, duration, intensity and timing) and measures of adiposity and body mass, physical activity, sedentary behaviour, sleep, diet and stress. We will also assess whether these relationships vary by socio-demographic factors.

METHODS

We will include studies that explore longitudinal associations between childcare attendance in children aged <6 years not in primary school at first assessment and body weight, adiposity, physical activity, diet, sleep and stress. We will limit studies to those involving middle- and high-income countries. Two independent reviewers will screen search results in two stages: (1) title and abstract and (2) and full text. One reviewer will extract relevant data and a second will verify this information. We will assess risk of bias of included studies using an adaption of the United States Department of Agriculture National Evidence Library Bias Assessment Tool. We will tabulate and summarise results narratively. We may conduct meta-analysis if at least five studies report comparable data.

DISCUSSION

To our knowledge, this will be the first systematic review to summarise the existing evidence on longitudinal associations between childcare and adiposity, body mass and obesity-related risk factors. The results will be of relevance to other researchers, childcare practitioners and policy makers.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42015027233.

Cortisol levels of infants in center care across the first year of life: links with quality of care and infant temperament

Cortisol concentrations of older children in childcare centers have been found to be higher than at home. This study focuses on infant cortisol in childcare centers throughout the first year of life, and aims to investigate whether inter-individual differences can be explained by temperament, the quality of maternal behavior, and the quality of center care. Sixty-four infants were followed for 9 months after entering care at 3 months of age. Salivary samples were taken at 10.00 h and 16.00 h in center care (in post-entry weeks 1, 2, 3, 4, 8, 12, 16, 24, and 36) and at home (in post-entry weeks 1, 24, and 36). Prior to entry, mothers completed a temperament questionnaire and the quality of maternal behavior (sensitivity and cooperation) was observed during routine bathing sessions. Subsequently, the infants were visited three times at center care to observe the quality of infant's interactive experiences with their professional caregiver. Longitudinal regression models showed that both morning and afternoon cortisol were higher in center care compared to home. Longitudinal regression models showed that infants receiving higher quality of maternal behavior displayed higher morning cortisol in center care, compared to infants receiving lower quality of maternal behavior. Higher quality of maternal behavior was also related to higher afternoon cortisol in center care, but only in infants high in negative emotionality. Center care quality was not related to cortisol. In sum, young infants show higher cortisol concentrations in center care that are related to infant temperament and quality of maternal behavior at home.