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

Association of perinatal characteristics with biomarkers of stress and inflammation in young adults: An exploratory study

General peri- and postnatal characteristics may serve as markers linking pre- or early postnatal events to later health outcomes, which in turn are associated with altered stress- and immune system activity. Our exploratory study investigated whether A) the common perinatal measures "birth weight" and "birth mode" and B) the postnatal characteristics "breastfeeding" and "vaccination status" are associated with markers of stress systems - the hypothalamic-pituitary-adrenal (HPA) axis and autonomous nervous system (ANS) - and inflammation in healthy young adults (n = 68, females: 70.6 %, mean age: 24.21 years, SD = 4.38) exposed to psychosocial challenge, the 'Trier Social Stress Test' (TSST). Salivary cortisol, alpha-amylase (sAA) and plasma interleukin-6 (IL-6) were assessed before, during and after the TSST. Participants provided information on peri- and postnatal characteristics. Linear regressions were performed to determine whether peri-/postnatal variables predict basal and stress-response-related biomarker levels. Controlling for sex and sex hormone use as relevant confounders, we found a significant association between birth weight and cortisol recovery (p = 0.032), with higher birth weight predicting higher cortisol recovery values. There were no other significant associations between predictor and outcome variables. Our results show that, in healthy young adults of mixed gender, normal-ranged birth weight is related to the cortisol response to psychosocial stress, indicating a long-term association of this perinatal marker with HPA axis function. In contrast, birth weight was not associated with markers of the ANS stress response or inflammation in adulthood. Our results further suggest that the measures birth mode, duration of breastfeeding, and vaccination status at 4 months of age do not relate to markers of the inflammatory and stress systems in adulthood.

Preterm birth: A neuroinflammatory origin for metabolic diseases?

Preterm birth and its related complications have become more and more common as neonatal medicine advances. The concept of "developmental origins of health and disease" has raised awareness of adverse perinatal events in the development of diseases later in life. To explore this concept, we propose that encephalopathy of prematurity (EoP) as a potential pro-inflammatory early life event becomes a novel risk factor for metabolic diseases in children/adolescents and adulthood. Here, we review epidemiological evidence that links preterm birth to metabolic diseases and discuss possible synergic roles of preterm birth and neuroinflammation from EoP in the development of metabolic diseases. In addition, we explore theoretical underlying mechanisms regarding developmental programming of the energy control system and HPA axis.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Mental health, pain and tiredness in adults born very preterm or with very low birthweight

AIM

Adults born preterm have increased risk of mental health problems and other neurodevelopmental conditions. We aimed to investigate associations of mental health with pain and tiredness in adults born very preterm (VP; <32 weeks) or very low birthweight (VLBW; <1500 g) and at term, and whether these associations are influenced by physical activity.

METHODS

As part of an EU Horizon 2020 project, individual participant data from six prospective cohort studies were harmonised for 617 VP/VLBW and 1122 term-born participants. Mental health was assessed by the Achenbach System of Empirically Based Assessment Adult Self-Report. Pain and tiredness were harmonised based on specific items from self-reported questionnaires. Associations between mental health and pain or tiredness were explored by linear regression.

RESULTS

An increase in the mental health scales internalising, externalising and total problems was associated with increased pain and tiredness in the preterm and term group alike. Results were maintained when adjusting for physical activity.

CONCLUSION

The findings indicate that associations between mental health, pain and tiredness in adults are independent of gestation or birthweight. Future research should explore other potential mechanisms that may underlie the increased risk of mental health problems in the preterm population.

Saliva cortisol diurnal variation and stress responses in term and preterm infants

OBJECTIVE

To determine if preterm birth is associated with adaptation of the hypothalamic-pituitary-adrenal (HPA) axis and whether HPA axis programming relates to the degree of prematurity (defined as extremely preterm birth at <28 weeks or very preterm birth at 28-32 weeks gestation).

DESIGN

This study reports findings from a prospective birth cohort. Saliva cortisol concentrations were measured prevaccination and postvaccination, and in the morning and evening, at 4 months chronological age.

SETTING

Infants born at a single Scottish hospital.

PARTICIPANTS

45 term-born, 42 very preterm and 16 extremely preterm infants.

OUTCOMES

Cortisol stress response to vaccination (postvaccination minus prevaccination cortisol concentrations), diurnal slope (log-transformed morning minus log-transformed evening cortisol values) and mean log-transformed daily cortisol.

RESULTS

Compared with infants born at term, infants born extremely preterm had a blunted cortisol response to vaccination (5.8 nmol/L vs 13.1 nmol/L, difference in means: -7.3 nmol/L, 95% CI -14.0 to -0.6) and a flattened diurnal slope (difference in geometric means: -72.9%, 95% CI -87.1 to -42.8). In contrast, the cortisol response to vaccination (difference in means -2.7 nmol/L, 95% CI -7.4 to 2.0) and diurnal slope at 4 months (difference in geometric means: -33.6%, 95% CI -62.0 to 16.0) did not differ significantly in infants born very preterm compared with infants born at term.

CONCLUSIONS

Infants born extremely preterm have blunted cortisol reactivity and a flattened diurnal slope. These patterns of HPA axis regulation are commonly seen after childhood adversity and could contribute to later metabolic and neurodevelopmental phenotypes observed in this population.

Association between antenatal glucocorticoid exposure and the activity of the stress system, cognition, and behavior in 8- to 9-year-old children: A prospective observational study

INTRODUCTION

Glucocorticoid (GC) -induced fetal programming of the activity of the hypothalamus-pituitary-adrenal axis (HPAA) and its associated cognitive and behavioral consequences in later life have been well characterized in several animal species. However, information on humans is scarce. In this study, we examined HPAA activity markers and associated outcomes at 8 to 9 years of age among children prenatally exposed to GC for suspected preterm birth. Our hypothesis was that antenatal exposure to the betamethasone (BM) is associated with exacerbation of HPAA activity in childhood.

MATERIAL AND METHODS

Prospective observational study in 31 children whose mothers received single (n = 19) or multiple (n = 12) courses of BM for threatened preterm birth but born with normal weight appropriate for the gestational age (median 37+⁶  weeks of gestation) compared with 38 non-exposed, age-matched children. Primary end point was the activity of the HPAA in response to the Trier Social Stress Test. Secondary end points were changes in autonomic nervous system (ANS) activity, cognitive performance (IQ), attention-deficit/hyperactivity disorder (ADHD) symptoms, and electrocortical activity (EEG).

RESULTS

There was no statistically significant difference in HPAA activity markers between antenatal BM exposed and unexposed groups. ANS activity in BM-exposed children shifted towards a higher parasympathetic tone reflected by a higher overall high-frequency band power of heart rate variability. IQ scores were within normal limits for both groups; however, BM-exposed children had lower IQ scores than the unexposed group. BM-exposed group had marginally more ADHD core symptoms and increased electrocortical activity in the occipital brain region compared with controls. A monotonic dose-response relationship between BM exposure and activity of the ANS and IQ was estimated in post-hoc analyses.

CONCLUSIONS

Antenatal exposure to BM in the context of threatened preterm birth was not associated with changes in HPAA activity in childhood. However, BM exposure may be associated with changes in ANS activity. Antenatal GC prophylaxis is a valuable and often life-saving therapy, but its prescription may warrant a well-balanced risk-benefit assessment.

Cortisol and Cortisone in Early Childhood in Very-Low-Birthweight Infants and Term-Born Infants

INTRODUCTION

Besides programming of the hypothalamic-pituitary-adrenal (HPA) axis, changes in the activity of 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) could contribute to the later metabolic and cardiovascular consequences of preterm birth.

OBJECTIVE

We compared serum cortisol, cortisone, and cortisol/cortisone ratio in early childhood in very-low-birthweight (VLBW) infants and term appropriate for gestational age (AGA) born infants.

METHODS

We included 41 VLBW infants, participating in the randomized controlled Neonatal Insulin Replacement Therapy in Europe trial, and 64 term AGA-born infants. Cortisol and cortisone were measured in blood samples taken at 6 months and 2 years corrected age (VLBW children) and at 3 months and 1 and 2 years (term children). At 2 years of (corrected) age (HDL) cholesterol, triglycerides, glucose, and insulin were also measured.

RESULTS

During the first 2 years of life, cortisol/cortisone ratio is higher in VLBW children compared to term children. In the total group of children, cortisol/cortisone ratio is positively related to triglycerides at 2 years of (corrected) age. In VLBW children, over the first 2 years of life both cortisol and cortisone are higher in the early-insulin group compared to the standard care group.

CONCLUSIONS

In VLBW infants, lower 11β-HSD2 activity probably contributes to the long-term metabolic and cardiovascular risks. In VLBW infants, early insulin treatment could affect programming of the HPA axis, resulting in higher cortisol and cortisone levels during early childhood.

Premature Birth and Developmental Programming: Mechanisms of Resilience and Vulnerability

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

Adrenal Steroid Metabolism and Blood Pressure in 5- to 7-Year-Old Children Born Preterm as Compared to Peers Born at Term

Background: Previous studies indicated preterm birth to be a risk factor for hypertension in adolescence and adulthood. However, studies in children investigating the underlying mechanisms are scarce. Objective: We hypothesized children born preterm to have higher excretion of cortisol and/or androgen metabolites per day concomitantly with higher blood pressure as compared to peers born at term. We thus aimed to compare urinary steroid profiles and blood pressure between 5- to 7-year-old children born preterm and peers born at term. Furthermore, aldosterone precursor excretion per day was compared between both groups. Methods: Blood pressure was measured in 236 children (preterms n = 116; gestational age 29.8 ± 2.6 (30; 24-33) weeks [mean ± standard deviation (median; range)]) using an automatic oscillometric device. Urinary steroid profiles were determined in 24-h urine samples (preterms n = 109; terms n = 113) using gas chromatographic-mass spectrometric analysis. To assess excretion of cortisol and androgen metabolites per day, major cortisol and androgen metabolites were summed, respectively. To assess aldosterone excretion per day tetrahydrocorticosterone, 5α-tetrahydrocorticosterone, and tetrahydro-11-deydrocorticosterone were summed. Results: Multiple regression analyses showed prematurity to be associated with systolic but not with diastolic blood pressure. When adjusted for potential confounders (prematurity, gender, age at day of examination, being born small for gestational age, breastfeeding, accelerated weight gain during infancy, family history of cardiovascular disease, parental hypertension, and body mass index) prematurity was shown to be associated with an increase in systolic blood pressure by 2.87 mmHg (95% confidence interval 0.48-5.27; p = 0.02). Cortisol, androgen metabolite, and aldosterone precursor excretion per day were not higher in individuals born preterm. In contrast to our hypothesis, multiple regression analysis showed prematurity to independently decrease cortisol and aldosterone precursor excretion per day (p < 0.001 and 0.04, respectively). Conclusion: This study provides further evidence for systolic blood pressure to be higher after preterm birth as early as at the age of 5 to 7 years. However, this seems not to be explained by elevated excretion of cortisol and/or androgen metabolites.

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

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

Delivery room skin-to-skin contact in preterm infants affects long-term expression of stress response genes

Premature birth is a traumatic event that puts mother and child at risk for subsequent psychopathology. Skin-to-skin contact in the form of intermittent kangaroo mother care has been shown to positively affect the infant's stress response and cognitive development, but underlying mechanisms remain unclear. Moreover, first skin-to-skin contact is usually delayed for days after birth. In the delivery room skin-to-skin study (DR-SSC), a prospective randomized controlled trial conducted from 2/2012 to 7/2015, we set out to assess the effect of delivery room skin-to-skin contact on the infant's mRNA expression of six key molecules involved in stress response and neurobehavioral development at hospital discharge. 88 firstborn, singleton preterm infants (born at 25-32 weeks of gestational age) were included. In the delivery room after initial stabilization, infants were randomized to either 60 min of skin-to-skin or 5 min of visual contact with their mother. In this explorative add-on study on the original DR-SSC study, we determined the expression of six important stress response genes (CRHR1 and CRHR2, AVP, NR3C1, HTR2A, and SLC6A4) in peripheral white blood cells of infants during routine blood sampling upon hospital discharge (corrected gestational age of 40 weeks). Infants were followed up to six months corrected age. Relative mRNA expression of the corticotropin releasing hormone receptor 2 (CRH R2), the glucocorticoid receptor gene (NR3C1), and the serotonin transporter gene (SLC6A4) was significantly reduced in the delivery room SSC infants. Additionally, gene expression of CRH R2 showed a correlation with HPA axis reactivity and parameters of mother-child interaction at six months corrected age. Our results highlight the importance of delivery room mother-child skin-to-skin contact and underline the urgent need for in-depth studies on the underlying molecular mechanisms.

Pain response to vaccination in newborn infants of diabetic mothers

BACKGROUND

Response to pain is altered in infants who were exposed to pain- and stressful events in the neonatal period. Infants of diabetic mothers receive several heel sticks after birth for measuring blood glucose and thus may show changes in their behavioral and physiologic response to pain. Moreover, maternal hyperglycemia may alter activity of the hypothalamic pituitary adrenal (HPA) axis reactivity.

STUDY DESIGN

In total, 43 infants of diabetic mothers and 30 control infants were included into the study. Response to pain was assessed at 3 months of age following two intramuscular injections for vaccination. We assessed behavioral (Bernese pain scale), physiologic (heart rate) and hormonal (salivary cortisol) pain response to vaccination as well as spinal sensitization (flexion withdrawal reflex).

RESULTS

Infants of diabetic mothers received a median number of 5 [4-19] painful events compared to 1 [1-3] in the control group. Heart rate reactivity differed significantly between groups. Infants of diabetic mothers had higher peaks (p = 0.002) and needed more time to recover to baseline (p < 0.001). Moreover, infants of diabetic mothers showed higher peak cortisol (p = 0.001) and a higher relative cortisol increase (p = 0.015). Flexor withdrawal reflex thresholds were significantly lower in infants of diabetic mothers (p = 0.003).

CONCLUSION

The increase of physiologic and hormonal responses to pain in infants of diabetic mothers is probably caused by repeated painful events and an altered metabolic profile.

Influence of race on the effect of premature birth on salivary cortisol response to stress in adolescents

BACKGROUND

Adolescents born preterm have altered hypothalamic-pituitary-adrenal axis function with a blunted cortisol stress response, however, the influences of intrauterine growth restriction and race are unclear.

METHODS

We measured salivary cortisol before and 20 min after a maximal-exercise stress test and calculated the cortisol stress response. We used linear regression to compare cortisol stress responses between preterm and term groups, adjusting for birth weight z-score and maternal hypertension, and examined effect modification by race and sex.

RESULTS

We evaluated 171 adolescents born preterm with very low birth weight and 50 born term. Adolescents born preterm had reduced cortisol stress response compared to term (0.03 vs. 0.08 μg/dL, p = 0.04). This difference was race dependent: non-Black adolescents born preterm had significantly reduced cortisol stress response compared to those born at term (adjusted β: -0.74; 95% CI -1.34, -0.15), while there was no difference in Black adolescents (0.53; -0.16, 1.22). Sex did not modify the relationship.

CONCLUSIONS

Adolescents born preterm exhibit a reduced salivary cortisol response to exercise stress, suggesting long-term alterations in the hypothalamic-pituitary-adrenal axis. This relationship was evident in non-Black but not in Black adolescents, suggesting that race may modify the influence of preterm birth on stress alterations of the hypothalamic-pituitary-adrenal axis.

Personal perspectives: Infant pain—A multidisciplinary journey

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

Adrenal function links to early postnatal growth and blood pressure at age 6 in children born extremely preterm

BACKGROUND

Low birth weight in term-born individuals correlates with adverse cardiometabolic outcomes; excess glucocorticoid exposure has been linked to these relationships. We hypothesized that cortisol and adrenal androgens would correlate inversely with birthweight and directly with markers of cardiometabolic risk in school-aged children born extremely preterm; further, preterm-born would have increased cortisol and adrenal androgens compared to term-born children.

METHODS

Saliva samples were obtained at age 6 from 219 preterm-born children followed since birth and 40 term-born children and analyzed for dehydroepiandrosterone (DHEA) and cortisol. Cortisol was also measured at home (awakening, 30' later, evening).

RESULTS

For preterm-born children, cortisol and DHEA correlated inversely with weight and length Z-scores at 36 weeks PMA and positively with systolic BP. DHEA was higher in preterm-born than term-born children (boys p < 0.01; girls p = 0.04). Cortisol was similar between preterm-born and term-born at study visit; however, preterm-born children showed a blunted morning cortisol. In term-born children, DHEA correlated with BMI (p = 0.04), subscapular, and abdominal skinfold thicknesses (both p < 0.01).

CONCLUSION

Cortisol and DHEA correlated inversely with early postnatal growth and directly with systolic BP in extremely preterm-born children, suggesting perinatal programming. Blunted morning cortisol may reflect NICU stress, as seen after other adverse childhood experiences (ACEs).

Postnatal relative adrenal insufficiency results in methylation of the glucocorticoid receptor gene in preterm infants: a retrospective cohort study

Background

To investigate the relationship between early-life stress and glucocorticoid receptor (GR) gene methylation, which may result in long-lasting neurodevelopmental impairment, we performed a longitudinal analysis of the methylation ratio within the GR gene promoter 1F region using next-generation sequencing in preterm infants.

Cell-free DNA was extracted from the frozen serum of 19 preterm birth infants at birth and at 1 and 2 months after birth. All were admitted to the neonatal intensive care unit of Juntendo University Shizuoka Hospital between August 2014 and May 2016 and suffered from chronic lung disease (CLD).

Through bisulfite amplicon sequencing using an Illumina Miseq system and Bismark-0.15.0 software, we identified the rate of cytosine methylation.

Results

Patients’ sex and body weight standard deviation were extracted as the associated independent variables at birth. Sex, glucocorticoid administration for treating CLD, and postnatal invasive procedures (surgical operation and blood sampling) were extracted as the associated independent variables at 1 month. Methylation rates increased significantly between postnatal 1 and 2 months at 9 of the 39 CpG sites. Postnatal glucocorticoid administration to treat circulatory collapse was the most-associated independent variable with a positive regression coefficient for a change in methylation rate at these nine CpG sites. It also influenced the methylation ratio at 22 of the 39 CpG sites at 2 months of age. The standard deviation (SD) score at birth was extracted as an independent variable, with a negative regression coefficient at 9 of the 22 CpG sites together with glucocorticoid administration.

Conclusions

The results of this study indicate that a prenatal environment that results in intrauterine growth restriction and postnatal relative adrenal insufficiency requiring glucocorticoid administration leads to GR gene methylation. That, in turn, may result in neurodevelopmental disabilities.

Heart rate variability and salivary cortisol in very preterm children during school age

The autonomic nervous system (ANS) plays a major role in the human stress response and reflects physical and psychological adaptability to a changing environment. Long-term exposure to early life stressors may alter the function of the ANS. The present study examines differences in the ANS between children born very preterm and full-term as well as the association between the ANS and the hypothalamic-pituitary-adrenal (HPA) axis, the other main branch of the human stress system. Fifty-four healthy children born very preterm (<32nd gestational week) and 67 full-term children aged 7-12 years provided data for the present study. Polysomnography (PSG) assessments were obtained during a night at the children's home in lying position at rest (wake) and during different sleep stages (stage 2 sleep, slow wave sleep, rapid-eye-movement sleep). Autonomic function was assessed by use of heart rate variability, specifically low frequency power (LF), high frequency power (HF), total spectral power (Tot Pow), and the LF/HF ratio. HPA axis activity was measured using salivary cortisol the next morning at awakening, 10, 20, and 30min later. Children born very preterm had lower LF/HF ratio during wake and stage 2 sleep compared to full-term children. Moreover, higher LF, Tot Pow, and LF/HF ratio during wake, stage 2 sleep, and REM sleep were related to more post-awakening cortisol secretion. The present study provides evidence on long-term ANS alterations after very preterm birth. Moreover, findings suggest a relation between the ANS and the HPA axis and therefore support the notion of mutual feedback between the two human stress systems.

Adults born preterm: a review of general health and system-specific outcomes

In this review of 126 publications, we report that an overwhelming majority of adults born at preterm gestations remain healthy and well. However, a small, but a significant fraction of them remain at higher risk for neurological, personality and behavioural abnormalities, cardio-pulmonary functional limitations, systemic hypertension and metabolic syndrome compared to their term-born counterparts. The magnitude of increased risk differed across organ systems and varied across reports. The risks were proportional to the degree of prematurity at birth and seemed to occur more frequently among preterm infants born in the final two decades of the 20th century and later. These findings have considerable public health and clinical practice relevance.

CONCLUSION

Preterm birth needs to be considered a chronic condition, with a slight increase in the risk for long-term morbidities among adults born preterm. Therefore, obtaining a history of gestational age and weight at birth should be a routine part of care for patients of all age groups.

Glucocorticoid Programming in Very Preterm Birth

Very preterm (i.e., <32 weeks of gestation) infants admitted to the neonatal intensive care unit are compromised in their abilities to respond adequately to common threats like hemodynamic changes and reduced energy supplies, which is partly attributable to adrenocortical insufficiency. Conversely, later in life, these infants show features of increased glucocorticoid bioactivity, such as abdominal fat distribution, raised blood pressure, insulin resistance and diabetes mellitus type 2. It has been suggested that the very preterm newborn responds to the adverse postnatal environment with a sustained elevation in hypothalamus-pituitary-adrenal axis activity that persists beyond infancy. This has implications for subsequent growth, body composition, metabolism, neurodevelopment and, ultimately, long-term disease risk. The mechanisms underpinning these associations are not fully elucidated yet. This review gives a brief summary of studies that investigated adrenocortical function in very preterm newborns and how the axis changes with age, as a possible explanation for the association between prematurity and long-term outcome.

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

CONTEXT

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

OBJECTIVE

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

DATA SOURCES

Adults Born Preterm International Collaboration.

STUDY SELECTION

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

DATA EXTRACTION

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

RESULTS

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

LIMITATIONS

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

CONCLUSIONS

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

Programming of the Hypothalamus-Pituitary-Adrenal Axis by Very Preterm Birth

BACKGROUND

Many very preterm (i.e., <32 weeks of gestation) newborns fail to mount an adequate adrenocortical response to stress or illness, termed relative adrenal insufficiency. Conversely, later in life these infants show features of increased glucocorticoid bioactivity, such as abdominal adiposity, insulin resistance, raised blood pressure, shorter stature and internalizing problem behavior.

SUMMARY

Studies suggested that very preterm newborns have impairments along multiple levels of the hypothalamus-pituitary-adrenal (HPA) axis. Among the impairment were defects in: (1) the pituitary responsiveness to exogenous corticotropin-releasing hormone, (2) 11β-hydroxylase activity, and (3) the interconversion between cortisol and inert cortisone. There is some evidence suggesting that later in life these infants have an increased basal secretion rate of cortisol and adrenal hyperandrogenism. However, the response to acute (psychosocial) stress was blunted rather than enhanced in them. The mechanisms explaining this switch in HPA axis activity are complex and not yet fully understood. Key Messages: Very preterm newborns have several impairments along the HPA axis that could impede an adequate adrenocortical response to stress or illness. Later in life, these infants are predisposed to increased HPA axis activity, which could partially explain their phenotype.

Psychiatric Disorders and General Functioning in Low Birth Weight Adults: A Longitudinal Study

OBJECTIVE

To examine psychiatric morbidity and overall functioning in adults born with low birth weight compared with normal birth weight controls at age 26 years and to study longitudinal trajectories of psychiatric morbidity from early adolescence to adulthood.

METHODS

Prospective cohort study wherein 44 preterm very low birth weight (≤1500 g), 64 term small for gestational age (SGA; <10th percentile), and 81 control adults were examined using the MINI-International Neuropsychiatric Interview: M.I.N.I. Plus, Norwegian version, the Global Assessment of Functioning, and questions on daily occupation and level of education. Prevalence of psychiatric disorders from previous follow-ups at age 14 and 19 years were included for longitudinal analysis.

RESULTS

From adolescence to adulthood, the term SGA group had a marked increase in the estimated probability of psychiatric disorders from 9% (95% confidence interval, 4-19) to 39% (95% confidence interval, 28-51). At 26 years, psychiatric diagnoses were significantly more prevalent in the preterm very low birth weight group (n = 16, 36%; P = .003) and the term SGA group (n = 24, 38%; P = .019) compared with the control group (n = 11, 14%). Both low birth weight groups had lower educational level and functioning scores than controls and a higher frequency of unemployment and disability benefit.

CONCLUSIONS

Low birth weight was a substantial risk factor for adult psychiatric morbidity and lowered overall functioning. The results underscore the need for long-term follow-up of low birth weight survivors through adolescence and adulthood, focusing on mental health. The longitudinal increase in psychiatric morbidity in the term SGA group calls for additional investigation.

Prenatal betamethasone exposure and psychopathology risk in extremely low birth weight survivors in the third and fourth decades of life

BACKGROUND

Mortality rates among extremely low birthweight (ELBW) infants have declined since the advent of antenatal glucocorticoid use. However, the long term neuropsychiatric effects of exposure are not well understood. We utilized the world's oldest longitudinally followed cohort of ELBW survivors to compare psychopathology over two decades in adulthood in those exposed to prenatal betamethasone and those who were not.

METHODS

ELBW survivors (n=179) and matched normal birth weight (NBW) controls (n=145) completed the Young Adult Self-Report questionnaire at 22-26 and 29-36 years, and the Beck Depression and Anxiety Inventories at 29-36 years. Symptom levels and rates of clinically significant psychiatric problems were compared in ELBW survivors whose mothers were administered steroids during pregnancy (ELBW-S n=63), ELBW participants who were not (ELBW-NS, n=79), and NBW controls.

RESULTS

At 22-26, ELBW-S had higher levels of anxiety, depressive, and avoidant personality symptoms, and a 3 to 5-fold increase in the odds of clinically significant levels of these problems compared to NBW controls, whereas ELBW-NS did not. These associations were maintained at 29-36, when ELBW-S participants exhibited a 3 to 10-fold increase in the odds of clinically significant anxiety and avoidant personality problems compared to NBW controls. At both time points, the odds of clinically significant anxiety problems were more than 3 times higher among ELBW-S than in ELBW-NS.

CONCLUSION

ELBW adults exposed to prenatal betamethasone manifest higher levels of anxiety and depression than those who were not, and may represent a group of preterm survivors at particularly high psychiatric risk.

Salivary and hair glucocorticoids and sleep in very preterm children during school age

Very preterm birth involves increased stress for the child, which may lead to programming of the hypothalamic-pituitary-adrenal (HPA) axis activity and poor sleep in later life. Moreover, there is evidence for a relationship between HPA axis activity and sleep. However, research with objective sleep measures in very preterm children during school-age is rare. Eighty-five healthy children born very preterm (<32nd gestational week) and 91 full-term children aged 7-12 years were recruited for the present study. To assess HPA axis activity, salivary cortisol was measured at awakening, 10, 20, and 30min later. In addition, hair cortisol and cortisone concentrations were quantified using liquid chromatography tandem mass spectrometry to assess cumulative endocrine activity over the preceding months. One night of in-home polysomnographic sleep assessment was conducted to assess sleep duration, sleep continuity, and sleep architecture. Children born very preterm showed significantly lower levels of cortisol at awakening and lower overall post-awakening cortisol secretion, lower cortisone in hair, and earlier sleep onset than full-term children. Across the whole sample, overall post-awakening cortisol secretion was positively related to sleep onset time and negatively to sleep duration. The association between prematurity status and post-awakening cortisol secretion was partially mediated by earlier sleep onset time. In conclusion, this study provides evidence for a possible down-regulation of the HPA axis activity and slightly earlier sleep phase in very preterm children during school age.

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

Background

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

Methods

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

Results

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

Conclusions

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

Long-Term Outcomes of Very Preterm Birth

Very preterm birth has become more frequent during the past decades due to progress in reproductive medicine, more frequent indicated preterm births due to maternal illnesses, and increasing maternal age. Moreover, survival rates of very preterm children have increased due to improved neonatal management. However, very preterm-born children, adolescents, and young adults are at increased risk for poor cognitive function and socio-emotional problems, which is of growing public health concern. Very premature birth has been studied to unravel consequences of a nonoptimal environment during a developmental period which under normal circumstances would be the last trimester of fetal development. For very preterm children, this developmental period partly occurs outside the womb, which leads to major distress for the immature newborn. For the cerebral cortex, the last trimester of pregnancy is a particularly sensitive period during which cortical folding takes place and the volume increases 4fold. During this period, even minor insults may cascade into disturbances of brain development. The most frequent complication after very preterm birth is related to insufficient functioning of the lungs, which may lead to hypoxic-ischemic incidences and damage to nervous tissue. This review presents evidence for long-term sequels of very premature birth regarding neurocognitive, academic, socio-emotional, and mental health development. Then it discusses possible underlying mechanisms including alterations in brain development, programming of the hypothalamic-pituitary-adrenal axis and circadian rhythmicity, as well as affected parent-child interaction patterns in families with very preterm children. Finally, intervention approaches to improve outcomes after very preterm birth are discussed and directions for future research presented.

Multidimensional response to vaccination pain in very preterm, moderate- to-late preterm and full-term infants at age three months

BACKGROUND

Very early life pain exposure and stress induces alterations in the developing brain and leads to altered pain sensitivity. In premature infants with a history of numerous early postnatal adverse events, behavioral responsiveness and hypothalamic-pituitary-adrenal (HPA) axis reactivity may show alterations as well.

AIMS

We compared a multidimensional response to a painful situation (vaccination) in three month old infants. The study involved very preterm, moderate to late preterm infants and full-term infants with varying exposure to pain and stress within the first weeks of life.

STUDY DESIGN

At the age of three months, we evaluated the infants' reactivity to intramuscular injections for immunization.

SUBJECTS

The study included 61 very preterm infants, 30 moderate to late preterm infants and 30 full-term infants.

OUTCOME MEASURES

We assessed heart rate recovery, Bernese pain Score and increase of salivary cortisol following vaccination. We also evaluated the flexor withdrawal reflex threshold as well as Prechtl's General Movements. Secondly, we assessed factors potentially influencing pain reactivity such as exposure to pain/stress, gender, use of steroids or opioids and mechanical ventilation.

RESULTS

Very preterm, moderate to late preterm and full-term infants showed different reactivity to pain in all analyzed aspects. Very preterm infants showed a lower level of behavioral and physiologic reactivity and exposure to pain/stress predicted lower cortisol increase.

CONCLUSION

At three months of age, very preterm infants show an altered level of HPA axis reactivity. Efforts aiming at minimizing pain and stress in premature infants should be taken.

Ambulatory blood pressure and its variability in adults born preterm

Adults born preterm have higher blood pressure (BP) than those born at term. Most studies have focused on preterm birth, and few have assessed BP variability, an independent risk factor of cardiovascular disease. We studied the association of preterm birth with 24-hour ambulatory BP, measured by an oscillometric device, in 42 young adults born early preterm (<34 weeks), 72 born late preterm (34-36 weeks), and 103 controls (≥37 weeks). Sleep was confirmed with accelerometry in 72.4% of subjects. The 24-hour systolic BP of adults born early preterm was 5.5 mm Hg higher (95% confidence interval, 1.9-9.3), awake systolic BP was 6.4 mm Hg higher (95% confidence interval, 2.8-10.1), and sleeping systolic BP was 2.9 mm Hg higher (95% confidence interval 0.3-7.5) when adjusted for age, sex, and use of accelerometry. The differences remained similar when adjusted for height, body mass index, physical activity, smoking, parental education, maternal body mass index, smoking during pregnancy, and gestational diabetes mellitus and attenuated slightly when adjusted for maternal hypertensive pregnancy disorders. Adults born early preterm also had higher BP variability as indicated by higher individual standard deviations of systolic BP and diastolic BP. Although our results were consistent with a dose-response relationship between shorter gestation and higher BP, the difference between the late preterm and term groups was not statistically significant. Our results suggest that the higher BP in adults born early preterm is present during both waking and sleeping hours, may be more pronounced during waking hours, and is accompanied by higher individual BP variability.

The role of sleep and the hypothalamic-pituitary-adrenal axis for behavioral and emotional problems in very preterm children during middle childhood

Very preterm children are at higher risk to develop behavioral and emotional problems, poor sleep, and altered hypothalamic-pituitary-adrenocortical activity (HPAA). However, knowledge on objective sleep and HPAA as well as their role for the development of behavioral and emotional problems in very preterm children is limited. Fifty-eight very preterm children (<32nd gestational week) and 55 full-term children aged 6-10 years underwent one night of in-home polysomnographic sleep assessment. HPAA was assessed with four saliva samples in the morning (morning cortisol secretion) and four saliva samples in the evening (evening cortisol secretion). Parents completed the Strengths and Difficulties Questionnaire (SDQ) to assess children's behavioral and emotional problems and a subscale of the Children's Sleep Habits Questionnaire to assess sleep disordered breathing. Very preterm children showed more behavioral and emotional problems (SDQ total behavioral/emotional difficulties, emotional symptoms), poorer sleep (more nocturnal awakenings, more stage 2 sleep, less slow wave sleep), and faster decreasing evening cortisol secretion compared to full-term children. Across the whole sample, more stage 2 sleep and/or less slow wave sleep were associated with more SDQ total behavioral/emotional difficulties, hyperactivity-inattention, and peer problems. Lower morning cortisol secretion and lower evening cortisol secretion were associated with more conduct problems. In very preterm children, increased SDQ total behavioral/emotional difficulties was partially explained by less restorative sleep including more stage 2 sleep and less slow wave sleep. This result points to the importance of restorative sleep for the behavioral and emotional development of very preterm children during middle childhood.

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

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

Preterm born 9-year-olds have elevated IGF-1 and low prolactin, but levels vary with behavioural and eating disorders

AIM

This study examined the relationship between hypothalamic-associated hormones and behavioural and eating disorders in children with low birthweight.

METHODS

We included 100 children (mean age 9.7 years): 39 were born preterm at <32 gestational weeks, 28 were full-term, but small for gestational age, and 33 were full-term controls. Behavioural histories were analysed, together with fasting blood samples of leptin, insulin, insulin-like growth factor-1 (IGF-I), prolactin, glucagon and cortisol.

RESULTS

Preterm children had lower prolactin (p = 0.01) and higher IGF-I than controls (p < 0.05, adjusted for confounders), despite being significantly shorter than the predicted target height (p < 0.001). More preterm children displayed behavioural disorders (38% versus 10%, p < 0.001) and eating disorders (26% versus 8%, p < 0.05) than full-term children. These disorders were associated with lower leptin (p < 0.01), insulin (p < 0.05) and IGF-I (p < 0.05), but correlations between these hormones and leptin were similar among the groups. Combined behavioural and eating disorders were only observed in preterm children, who were also the shortest in height.

CONCLUSION

Behavioural and eating disorders among preterm children were associated with low leptin, insulin and IGF-1. Low prolactin in all preterm children indicated an increased dopaminergic tonus, which might inhibit body weight incrementation. This raises speculation about IGF-I receptor insensitivity.

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

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

OBJECTIVE

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

DESIGN AND PARTICIPANTS

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

MEASUREMENTS

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

RESULTS

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

CONCLUSIONS

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

Plasma metabolomic profiling suggests early indications for predisposition to latent insulin resistance in children conceived by ICSI

BACKGROUND

There have been increasing indications about an epigenetically-based elevated predisposition of assisted reproductive technology (ART) offspring to insulin resistance, which can lead to an unfavorable cardio-metabolic profile in adult life. However, the relevant long-term systematic molecular studies are limited, especially for the IntraCytoplasmic Sperm Injection (ICSI) method, introduced in 1992. In this study, we carefully defined a group of 42 prepubertal ICSI and 42 naturally conceived (NC) children. We assessed differences in their metabolic profile based on biochemical measurements, while, for a subgroup, plasma metabolomic analysis was also performed, investigating any relevant insulin resistance indices.

METHODS & RESULTS

Auxological and biochemical parameters of 42 6.8±2.1 yrs old ICSI-conceived and 42 age-matched controls were measured. Significant differences between the groups were determined using univariate and multivariate statistics, indicating low urea and low-grade inflammation markers (YKL-40, hsCRP) and high triiodothyronine (T3) in ICSI-children compared to controls. Moreover, plasma metabolomic analysis carried out for a subgroup of 10 ICSI- and 10 NC girls using Gas Chromatography-Mass Spectrometry (GC-MS) indicated clear differences between the two groups, characterized by 36 metabolites linked to obesity, insulin resistance and metabolic syndrome. Notably, the distinction between the two girl subgroups was accentuated when both their biochemical and metabolomic measurements were employed.

CONCLUSIONS

The present study contributes a large auxological and biochemical dataset of a well-defined group of pre-pubertal ICSI-conceived subjects to the research of the ART effect to the offspring's health. Moreover, it is the first time that the relevant usefulness of metabolomics was investigated. The acquired results are consistent with early insulin resistance in ICSI-offspring, paving the way for further systematic investigations. These data support that metabolomics may unravel metabolic differences before they become clinically or biochemically evident, underlining its utility in the ART research.