Serotonin Transporter Gene (SLC6A4 ) Methylation Associates With Neonatal Intensive Care Unit Stay and 3-Month-Old Temperament in Preterm Infants

Sex-dimorphic pathways in the associations between maternal trait anxiety, infant BDNF methylation, and negative emotionality

Maternal antenatal anxiety is an emerging risk factor for child emotional development. Both sex and epigenetic mechanisms, such as DNA methylation, may contribute to the embedding of maternal distress into emotional outcomes. Here, we investigated sex-dependent patterns in the association between antenatal maternal trait anxiety, methylation of the brain-derived neurotrophic factor gene (BDNF DNAm), and infant negative emotionality (NE). Mother-infant dyads (N = 276) were recruited at delivery. Maternal trait anxiety, as a marker of antenatal chronic stress exposure, was assessed soon after delivery using the Stait-Trait Anxiety Inventory (STAI-Y). Infants' BDNF DNAm at birth was assessed in 11 CpG sites in buccal cells whereas infants' NE was assessed at 3 (N = 225) and 6 months (N = 189) using the Infant Behavior Questionnaire-Revised (IBQ-R). Hierarchical linear analyses showed that higher maternal antenatal anxiety was associated with greater 6-month-olds' NE. Furthermore, maternal antenatal anxiety predicted greater infants' BDNF DNAm in five CpG sites in males but not in females. Higher methylation at these sites was associated with greater 3-to-6-month NE increase, independently of infants' sex. Maternal antenatal anxiety emerged as a risk factor for infant's NE. BDNF DNAm might mediate this effect in males. These results may inform the development of strategies to promote mothers and infants' emotional well-being.

A preliminary investigation of epigenome-wide DNA methylation and temperament during infancy

This study provides preliminary evidence for an epigenetic architecture of infant temperament. At 12 months of age, blood was collected and assayed for DNA methylation and maternally reported infant temperament was assessed using the Infant Behavior Questionnaire in 67 mother-infant dyads. Epigenome-wide analyses showed that the higher order temperament dimensions Surgency and Negative Affect were associated with DNA methylation. The epigenetic signatures of Surgency and Negative Affect were situated at genes involved in synaptic signaling and plasticity. Although replication is required, these results are consistent with a biologically based model of temperament, create new avenues for hypothesis-driven research into epigenetic pathways that underlie individual differences in temperament, and demonstrate that infant temperament has a widespread epigenetic signature in the methylome.

Does preterm birth increase the initiation of antidepressant use during the postpartum? A population-based investigation

Background

Preterm birth may affect maternal mental health. We explored the relationship between preterm birth and the risk of initiating antidepressant use during the year after birth.

Methods

We conducted a population-based investigation using regional healthcare utilization databases. The exposure considered was preterm birth. The outcome was having at least one prescription for antidepressant medications during the year after birth. We used a log-binomial regression model including terms for maternal age at birth, nationality, educational level, parity, modality of conception, modality of delivery, use of other psychotropic drugs, and diabetes to estimate relative risk (RR) and 95% confidence intervals (CI) for the association between preterm birth and the initiation of antidepressant use. In addition, the absolute risk differences (ARD) were also computed according to the timing of birth.

Results

The cohort included 727,701 deliveries between 2010 and 2020 in Lombardy, Northern Italy. Out of these, 6,522 (0.9%) women had at least one prescription for antidepressant drugs during the year after birth. Preterm births were related to a 38% increased risk of initiation of antidepressant use during the year after birth (adjusted RR = 1.38; 95% CI: 1.25-1.52) for moderate to late preterm and to 83% (adjusted RR = 1.83; 95% CI: 1.46-2.28) for extremely and very preterm. Excluding women with only one antidepressant prescription, the association was consistent (adjusted RR = 1.41, 95%CI: 1.23-1.61 for moderate to late preterm and adjusted RR = 1.81, 95% CI: 1.31-2.49 for extremely and very preterm). Also, excluding women who used other psychotropics, the association remained consistent (adjusted RR = 1.39, 95%CI: 1.26-1.54 and adjusted RR = 1.91, 95% CI: 1.53-2.38, respectively for moderate to late and extremely and very preterm).

Conclusion

Women who delivered preterm may have an excess risk of initiation of antidepressant consumption during the first year after birth.

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

Background

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

Aims

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

Methods

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

Results

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

Conclusion

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

Health disparities in preterm births

Introduction

Black African American (B/AA) women have a 2-fold to 3-fold elevated risk compared with non-Hispanic White (W) women for preterm birth. Further, preterm birth is the leading cause of mortality among B/AA infants, and among survivors, preterm infant adverse health outcomes occur disproportionately in B/AA infants. Racial inequities in maternal and infant health continue to pose a public health crisis despite the discovery >100 years ago. The purpose of this study was to expand on reported preterm infant outcome disparities. A life-course approach, accumulation of lifelong stress, including discrimination, may explain social factors causing preterm birth rate and outcome inequities in B/AA mothers.

Methods

Anthropometric measures and clinical treatment information for 197 consented participants were milled from electronic health records across 4 years. The Neonatal Infant Stressor Scale was used to tally acute and chronic painful/stressful procedures. Neurobehavioral differences were investigated using the Neonatal Intensive Care Unit (NICU) Network Neurobehavioral Scale.

Results

B/AA mothers gave birth to preterm infants earlier than W mothers. NICU hospitalization stays were extended more than 2 weeks for the significantly smaller B/AA preterm infants in comparison to the age-matched W preterm infants. A higher number of chronic lifesaving procedures with demonstrated altered stress response patterns were recorded for B/AA preterm infants.

Discussion

This cross-sectional analysis of preterm birth rates and preterm infant developmental and neurodevelopmental outcomes are presented in the context of NICU stress and pain, with attendant implications for infant mortality and future health disparities. Preterm birth rate and outcome inequities further support the need to develop interventions and policies that will reduce the impact of discrimination and improve social determinants of health for Black, Indigenous, and other People of Color.

Neonatal stress exposure and DNA methylation of stress-related and neurodevelopmentally relevant genes: An exploratory study

BACKGROUND

Stress exposure during Neonatal Intensive Care Unit (NICU) stay may have long-lasting effects on neurodevelopmental outcomes in extremely preterm infants. Altered DNA methylation of stress-related and neurodevelopmentally relevant genes may be an underlying mechanism.

AIMS

This exploratory study aimed to investigate the association between neonatal stress exposure and DNA methylation in these genes at two different time points: early during the NICU stay (7-14 days after birth) and later, at discharge from the NICU.

SUBJECTS

We included 45 extremely preterm infants in this prospective cohort study, gestational age 24-30 weeks.

OUTCOME MEASURES

We collected fecal samples at days 7-14 (n = 44) and discharge (n = 28) and determined DNA methylation status in predefined regions of NR3C1, SLC6A4, HSD11B2, OPRM1, SLC7A5, SLC1A2, IGF2, NNAT, BDNF and GABRA6 using pyrosequencing. Because of low DNA concentrations in some fecal samples, we could do so in 25-50 % of collected samples. We prospectively quantified daily neonatal stress exposure using the Neonatal Infant Stressor Scale (NISS) and explored associations between cumulative NISS scores and average DNA methylation status.

RESULTS

Rates of methylation of most genes were not statistically different between day 7-14 and discharge, except for OPRM1. We found moderately high and mostly negative correlation coefficients upon discharge with the cumulative NISS for the NR3C1, SLC6A4, SLC1A2, IGF2, BDNF and OPRM1 genes, albeit not statistically significant.

CONCLUSIONS

Findings suggest that expression of stress-related and neurodevelopmentally relevant genes may be differently regulated following higher neonatal stress exposure. Larger studies should challenge the findings of this study and ideally test the effects on gene expression.

Mood and anxiety spectrum disorders detected by neuropsychiatric interviews in young adults born preterm: A prospective cohort study

BACKGROUND

Psychopathology has not yet been studied beyond pediatric age for all degrees of prematurity, including late-preterm, particularly in those who grew up with no apparent neurodevelopmental sequelae. This study aimed to examine psychopathological outcome following preterm birth and admission to neonatal intensive care in young adults without major neurodevelopmental and psychopathological problems that emerged during childhood.

METHODS

An Italian single-center prospective cohort study. Eighty-nine young adults (40 admitted to neonatal intensive care unit with less than 37 weeks of gestation and no medical history of other neurological or psychiatric conditions in childhood and 49 healthy peers born at term, matched by age, sex, and education) underwent neuropsychiatric interviews at the age of 20 ± 1 years; MINI International Neuropsychiatric Interview, Beck Depression Inventory and Barratt Impulsive Scale, results were correlated to individual neonatal data and cognitive measures.

RESULTS

We found a significantly higher prevalence of psychopathology at MINI score (22.5% vs. 4.2%; χ2 = 6.7; p = 0,010) and prevalence of previous stressful life events in the preterm compared to at-term group. B.D.I. (testing depression) and BIS-11(testing impulsivity) did not highlight a statistically significant difference between the groups. All patients had average I.Q., a statistically significant difference (p < 0.001) was observed between groups with a better performance in controls than cases.

CONCLUSIONS

Preterm infants attaining young adult age with otherwise typical development during childhood are at risk of psychopathology and lower resilience to stressful life events. The MINI interview could be a useful tool to highlight the psychopathology of preterm infants attaining adult age.

Scoping Review of Early Toxic Stress and Epigenetic Alterations in the Neonatal Intensive Care Unit

BACKGROUND

Preterm infants are uniquely vulnerable to early toxic stress exposure while in the neonatal intensive care unit (NICU) and also being at risk for suboptimal neurodevelopmental outcomes. However, the complex biological mechanisms responsible for variations in preterm infants' neurodevelopmental outcomes because of early toxic stress exposure in the NICU remain unknown. Innovative preterm behavioral epigenetics research offers a possible mechanism and describes how early toxic stress exposure may lead to epigenetic alterations, potentially affecting short- and long-term outcomes.

OBJECTIVE

The aim of this study was to review the relationships between early toxic stress exposures in the NICU and epigenetic alterations in preterm infants. The measurement of early toxic stress exposure in the NICU and effect of epigenetic alterations on neurodevelopmental outcomes in preterm infants were also examined.

METHODS

We conducted a scoping review of the literature published between January 2011 and December 2021 using databases PubMed, CINAHL, Cochrance Library, PsycINFO, and Web of Science. Primary data-based research that examined epigenetics, stress, and preterm infants or NICU were included.

RESULTS

A total of 13 articles from nine studies were included. DNA methylations of six specific genes were studied in relation to early toxic stress exposure in the NICU: SLC6A4, SLC6A3, OPRMI, NR3C1, HSD11B2, and PLAGL1. These genes are responsible for regulating serotonin, dopamine, and cortisol. Poorer neurodevelopmental outcomes were associated with alterations in DNA methylation of SLC6A4, NR3C1, and HSD11B2. Measurements of early toxic stress exposure in the NICU were inconsistent among the studies.

DISCUSSION

Epigenetic alterations secondary to early toxic stress exposures in the NICU may be associated with future neurodevelopmental outcomes in preterm infants. Common data elements of toxic stress exposure in preterm infants are needed. Identification of the epigenome and mechanisms by which early toxic stress exposure leads to epigenetic alterations in this vulnerable population will provide evidence to design and test individualized intervention.

Effects of kangaroo care on pain relief in premature infants during painful procedures: A meta-analysis

AIM

This study aimed to evaluate effects of kangaroo care on pain relief in premature infants during painful procedures.

DESIGN

A meta-analysis.

METHODS

Eight databases (Cochrane Library, PubMed, Embase, Web of Science, China Biology Medicine [CBM], China Science and Technology Journal Database [CSTJ], China National Knowledge Infrastructure [CNKI], and WanFang Data) were systematically reviewed from inception to November 2021 for randomized controlled and crossover trials.

RESULTS

Thirteen studies, including 2311 infants (kangaroo care: 1153, control: 1158) were analyzed. Kangaroo care had a moderate effect on pain relief during painful procedures in premature infants at a gestational age of 32-36 + 6 weeks but no effect at 28-31 + 6 weeks. Furthermore, 15 or 30 min of kangaroo care had a moderate effect and could markedly relieve pain at the instant of and 30/60 s after, had a small effect at 90 s after, and no effect at 120 s after the procedure.

PRACTICE IMPLICATIONS

Kangaroo care may be an effective nonpharmacologic alternative therapy to relieve procedural pain in premature infants born at a gestational age of 32-36 + 6 weeks.

Maternal and infant NR3C1 and SLC6A4 epigenetic signatures of the COVID-19 pandemic lockdown: when timing matters

Stress exposure during pregnancy is critically linked with maternal mental health and child development. The effects might involve altered patterns of DNA methylation in specific stress-related genes (i.e., glucocorticoid receptor gene, NR3C1, and serotonin transporter gene, SLC6A4) and might be moderated by the gestational timing of stress exposure. In this study, we report on NR3C1 and SLC6A4 methylation status in Italian mothers and infants who were exposed to the COVID-19 pandemic lockdown during different trimesters of pregnancy. From May 2020 to February 2021, 283 mother-infant dyads were enrolled at delivery. Within 24 h from delivery, buccal cells were collected to assess NR3C1 (44 CpG sites) and SLC6A4 (13 CpG sites) methylation status. Principal component (PC) analyses were used to reduce methylation data dimension to one PC per maternal and infant gene methylation. Mother-infant dyads were split into three groups based on the pregnancy trimester (first, second, third), during which they were exposed to the COVID-19 lockdown. Mothers and infants who were exposed to the lockdown during the first trimester of pregnancy had lower NR3C1 and SLC6A4 methylation when compared to counterparts exposed during the second or third trimesters. The effect remained significant after controlling for confounders. Women who were pregnant during the pandemic and their infants might present altered epigenetic biomarkers of stress-related genes. As these epigenetic marks have been previously linked with a heightened risk of maternal psychiatric problems and less-than-optimal child development, mothers and infants should be adequately monitored for psychological health during and after the pandemic.

Nursing Interventions That Promote Sleep in Preterm Newborns in the Neonatal Intensive Care Units: An Integrative Review

Sleep is a crucial factor for the psychological and physiological well-being of any human being. In Neonatal Intensive Care Units, preterm newborns' sleep may be at risk due to medical and nursing care, environmental stimuli and manipulation. This review aims to identify the nurses' interventions that promote sleep in preterm newborns in the Neonatal Intensive Care Units. An integrative review was conducted following Whittemore and Knafl's methodology and the 2020 Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. The research was carried out on the electronic databases PubMed, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and ScienceDirect, with a timeframe from 2010 to 2021. A total of 359 articles were initially identified. After selection and analysis, five studies were included in the sample. Interventions by nursing staff that promote sleep in preterm newborns in the Neonatal Intensive Care Units fall within three categories: environmental management, relaxation techniques and therapeutic positioning. Nurses play a vital role in implementing interventions that promote preterm newborns' sleep. They can positively affect preterm newborns' sleep by controlling environmental stimuli and applying relaxation techniques and therapeutic positioning to their care practices.

Neonatal frontal-limbic connectivity is associated with externalizing behaviours in toddlers with Congenital Heart Disease

Children with Congenital Heart Disease (CHD) are at increased risk of neurodevelopmental impairments. The neonatal antecedents of impaired behavioural development are unknown. 43 infants with CHD underwent presurgical brain diffusion-weighted MRI [postmenstrual age at scan median (IQR) = 39.29 (38.71-39.71) weeks] and a follow-up assessment at median age of 22.1 (IQR 22.0-22.7) months in which parents reported internalizing and externalizing problem scores on the Child Behaviour Checklist. We constructed structural brain networks from diffusion-weighted MRI and calculated edge-wise structural connectivity as well as global and local brain network features. We also calculated presurgical cerebral oxygen delivery, and extracted perioperative variables, socioeconomic status at birth and a measure of cognitively stimulating parenting. Lower degree in the right inferior frontal gyrus (partial ρ = -0.687, p < 0.001) and reduced connectivity in a frontal-limbic sub-network including the right inferior frontal gyrus were associated with higher externalizing problem scores. Externalizing problem scores were unrelated to neonatal clinical course or home environment. However, higher internalizing problem scores were associated with earlier surgery in the neonatal period (partial ρ = -0.538, p = 0.014). Our results highlight the importance of frontal-limbic networks to the development of externalizing behaviours and provide new insights into early antecedents of behavioural impairments in CHD.

Serotonin transporter gene methylation and emotional regulation in preschool children born preterm: A longitudinal evaluation of the role of negative emotionality in infancy

The aim of the study was to assess the contribution of negative emotionality at 3 months (T1) and serotonin transporter gene (SLC6A4) DNA methylation at 4.5 years of age (T2) to emotion regulation in pre-schoolers born very preterm and full-term. Forty one children (n = 21 born very preterm, n = 20 born full-term) participated in the study. Fretful behavior was assessed at T1 in response to the Face-to-FaceStill-Face (FFSF) paradigm. At T2, SLC6A4 DNA methylation was analyzed and emotion regulation was assessed using an observational procedure (i.e., the Pre-schooler Regulation of Emotional Stress, PRES). The very preterm group displayed higher emotion dysregulation during the PRES Reactivity phase than the full-term group. Higher levels of fretful behavior at 3 months were associated with greater emotional distress only for very preterm children with higher methylation at T2. No significant associations emerged in the full-term group. Despite current findings cannot be generalized owing to the relatively small sample size, this work provides preliminary longitudinal evidence about the link between negative emotionality during infancy, stress-linked epigenetic status at 4.5 years and emotion dysregulation in preschoolers born preterm.

Effects of swaddled and traditional tub bathing on stress and physiological parameters of preterm infants: A randomized clinical trial in China

PURPOSE

The present research aims to study the effects of swaddled and traditional tub bathing on premature infants to identify better ways to bathe.

DESIGN AND METHODS

Eligible premature infants (n = 60) were randomly assigned to either swaddled bathing or traditional tub bathing group. Stress scores and physiological indicators were measured 10 min before, immediately after, and 10 min after bathing. Crying times were also recorded for both groups. Data were reported as mean and standard deviation (SD) or frequency (percentage). For analyzing the data, the Student t-test and Chi-square test were employed.

RESULTS

Swaddled bathing has less effect on the respiratory rate, heart rate, and oxygen saturation (p < 0.05). Both bathing methods led to a decrease in the temperature of infants. Still, the temperature of infants 10 min after bathing, in the swaddled bathing group was rose higher than the traditional tub bathing (t = 2.813, p < 0.05). The stress score of the swaddled bathing group, immediately after and ten minutes after bathing was lower than the traditional tub bathing group. The crying time of the swaddled bathing group was 32 ± 24.740(s) lower than the traditional tub bathing group 94.43 ± 41.625(s).

CONCLUSIONS

The advantages of swaddled bathing over traditional tub bathing were validated for feasibility in China's preterm infants. Swaddled bathing is recommended method for bathing technique in the neonatal intensive care unit.

PRACTICE IMPLICATIONS

Swaddled bathing is beneficial for the development of premature infants, as it results in less noxious stimuli and stress on the developing premature neonates.

Maternal Mood and Perception of Infant Temperament at Three Months Predict Depressive Symptoms Scores in Mothers of Preterm Infants at Six Months

Postpartum depression is more prevalent in mothers and fathers of preterm infants compared to parents of full-term infants and may have long-term detrimental consequences for parental mental health and child development. The temperamental profile of an infant has been postulated as one of the important factors associated with parental depressiveness in the first months postpartum. This study aimed to examine the longitudinal relationship between depressive symptoms and perceived infant temperament at 3 months corrected age, and depressive symptoms at 6 months corrected age among mothers and fathers of infants born preterm. We assessed 59 families with infants born before the 34th gestational week using the Edinburgh Postnatal Depression Scale (EDPS) and the Infant Behavior Questionnaire-Revised. We found that mothers’ scores on EPDS and infants’ Orienting/regulation at 3 months corrected age predicted mothers’ EPDS scores at 6 months corrected age. In particular, higher depressive scores were related to higher depressive symptoms at 6 months corrected age, whereas higher infant Orienting/regulation was related to lower depressive symptoms at 6 months corrected age. Due to the low internal consistency of EPDS at 6 months for fathers, we were unable to conduct similar analyses for fathers. Our results point to the importance of considering both early indices of maternal mood as well as mother-reported measures of preterm infant temperament in the attempts to predict levels of maternal depressiveness in later months of an infant’s life. Further studies are urgently needed in order to better understand the associations between depressiveness and infant temperament in fathers, and with more consideration for the severity of the effects of infant prematurity.

The role of maternal touch in the association between SLC6A4 methylation and stress response in very preterm infants

Very preterm (VPT) infants requiring hospitalization in the Neonatal Intensive Care Unit (NICU) are exposed to several stressful procedural experiences. One consequence of NICU-related stress is a birth-to-discharge increased serotonin transporter gene (SLC6A4) methylation that has been associated with poorer stress regulation at 3 months of age. Maternal touch is thought to support infants' stress response, but its role in moderating the effects of SLC6A4 methylation changes is unknown. The aim of this study was to assess the role of maternal touch in moderating the association between increased SLC6A4 methylation and stress response in 3-month-old VPT infants. Twenty-nine dyads were enrolled and at 3 months (age corrected for prematurity), participated in the Face-to-Face Still-Face paradigm to measure infants' stress response (i.e., negative emotionality) and the amount of maternal touch (i.e., dynamic and static). Results showed that low level of maternal touch is associated with high level of negative emotionality during social stress. Furthermore, during NICU stay SLC6A4 methylation in VPT exposed to low level of maternal touch at 3 months was associated with increased negative emotionality. Thus, low levels of maternal static touch can intensify the negative effects of SLC6A4 epigenetic changes on stress response in 3-month-old VPT infants.

Exploring the Contribution of Proximal Family Risk Factors on SLC6A4 DNA Methylation in Children with a History of Maltreatment: A Preliminary Study

The cumulative effects of proximal family risk factors have been associated with a high number of adverse outcomes in childhood maltreatment, and DNA methylation of the serotonin transporter gene (SLC6A4) has been associated with child maltreatment. However, the relationships between proximal family risk factors and SLC6A4 methylation remains unexplored. We examined the association among cumulative family risk factors, maltreatment experiences and DNA methylation in the SLC6A4 gene in a sample of 33 child victims of maltreatment. We computed a cumulative family risk (CFR) index that included proximal family risk factors, such as drug or alcohol abuse, psychopathology, parents’ experiences of maltreatment/abuse in childhood, criminal history, and domestic violence. The majority of children (90.9%) experienced more than one type of maltreatment. Hierarchical regression models suggested that the higher the CFR index score and the number of maltreatment experiences, and the older the children, the higher the SLC6A4 DNA methylation levels. Although preliminary, our findings suggest that, along with childhood maltreatment experiences per se, cumulative proximal family risk factors are seemingly critically associated with DNA methylation at the SLC6A4 gene.

Neonatal Stress, Health, and Development in Preterms: A Systematic Review

CONTEXT

An overview of the full range of neonatal stressors and the associated clinical, laboratory, and imaging outcomes regarding infants' health and development may contribute to the improvement of neonatal care.

OBJECTIVE

To systematically review existing literature on the associations between all kinds of neonatal stressors and the health and development of preterm infants.

DATA SOURCES

Data sources included Embase, Medline, PsycINFO, the Cumulative Index to Nursing and Allied Health Literature, and reference lists.

STUDY SELECTION

Studies were eligible if they included a measure of neonatal stress during the NICU stay, reported clinical, laboratory, and/or imaging outcomes regarding health and/or development on discharge from the NICU or thereafter, included preterm infants, and were written in English or Dutch.

DATA EXTRACTION

Two reviewers independently screened the sources and extracted data on health and development. Study quality was assessed by using the Newcastle-Ottawa Quality Assessment Scale.

RESULTS

We identified 20 articles that reported on neonatal stress associated negatively with clinical outcomes, including cognitive, motor, and emotional development, and laboratory and imaging outcomes, including epigenetic alterations, hypothalamic-pituitary-adrenal axis functioning, and structural brain development. We found no evidence regarding associations with growth, cardiovascular health, parent-infant interaction, the neonatal immune system, and the neonatal microbiome.

LIMITATIONS

The studies were all observational and used different definitions of neonatal stress.

CONCLUSIONS

Neonatal stress has a profound impact on the health and development of preterm infants, and physicians involved in their treatment and follow-up should be aware of this fact.

Perinatal stress and methylation of the NR3C1 gene in newborns: systematic review

Adverse experiences in the perinatal period have been associated with the methylation of the human glucocorticoid receptor gene (NR3C1) and long-term diseases. We conducted a systematic review on the association between adversities in the perinatal period and DNA methylation in the 1 _F region of the NR3C1 gene in newborns. We explored the MEDLINE, Web of Science, Scopus, Scielo, and Lilacs databases without time or language limitations. Two independent reviewers performed the selection of articles and data extraction. A third participated in the methodological quality assessment and consensus meetings at all stages. Finally, ten studies were selected. Methodological quality was considered moderate in six and low in four. Methylation changes were reported in 41 of the 47 CpG sites of exon 1 _F. Six studies addressed maternal conditions during pregnancy: two reported methylation changes at the same sites (CpG 10, 13, 20, 21 and 47), and four at one or more sites from CpG 35 to 39. Four studies addressed neonatal parameters and morbidities: methylation changes at the same sites 4, 8, 10, 16, 25, and 35 were reported in two. Hypermethylation associated with stressful conditions prevailed. Hypomethylation was more often associated with protective conditions (maternal-foetal attachment during pregnancy, breast milk intake, higher birth weight or Apgar). In conclusion, methylation changes in several sites of the 1 _F region of the NR3C1 gene in newborns and very young infants were associated with perinatal stress, but more robust and comparable results are needed to corroborate site-specific associations.

Hidden pandemic: COVID-19-related stress, SLC6A4 methylation, and infants' temperament at 3 months

The COVID-19 pandemic represents a collective trauma that may have enduring stress effects during sensitive periods, such as pregnancy. Prenatal stress may result in epigenetic signatures of stress-related genes (e.g., the serotonin transporter gene, SLC6A4) that may in turn influence infants' behavioral development. In April 2020, we launched a longitudinal cohort study to assess the behavioral and epigenetic vestiges of COVID-19-related prenatal stress exposure in mothers and infants. COVID-19-related prenatal stress was retrospectively assessed at birth. SLC6A4 methylation was assessed in thirteen CpG sites in mothers and infants' buccal cells. Infants' temperament was assessed at 3-month-age. Complete data were available from 108 mother-infant dyads. Greater COVID-19-related prenatal stress was significantly associated with higher infants' SLC6A4 methylation in seven CpG sites. SLC6A4 methylation at these sites predicted infants' temperament at 3 months.

Biobehavioral organization shapes the immune epigenome in infant rhesus Macaques (Macaca mulatta)

How individuals respond to and cope with stress is linked with their health and well-being. It is presumed that early stress responsiveness helps shape the health of the developing organism, but the relationship between stress responsiveness and early immune function during development is not well-known. We hypothesized that stress responsiveness may shape epigenetic regulation of immune genes in infancy. We investigated whether aspects of behavioral responsiveness and hypothalamic-pituitary adrenal stress-response were associated with epigenome-wide immune cell DNA methylation patterns in 154 infant rhesus monkeys (3-4 months old). Infants' behavioral and physiological responses were collected during a standardized biobehavioral assessment, which included temporary relocation and separation from their mother and social group. Genome-wide DNA methylation was quantified using restricted representation bisulfite sequencing (RRBS) from blood DNA collected 2-hours post-separation. Epigenome-wide analyses were conducted using simple regression, multiple regression controlling for immune cell counts, and permutation regression, all corrected for false discovery rate. Across the variables analyzed, there were 20,368 unique sites (in 9,040 genes) at which methylation was significantly associated with at least one behavioral responsiveness or cortisol measure across the three analyses. There were significant associations in 442 genes in the Immune System Process ontology category, and 94 genes in the Inflammation mediated by chemokine and cytokine signaling gene pathway. Out of 35 candidate genes that were selected for further investigation, there were 13 genes with at least one site at which methylation was significantly associated with behavioral responsiveness or cortisol, including two intron sites in the glucocorticoid receptor gene, at which methylation was negatively correlated with emotional behavior the day following the social separation (Day 2 Emotionality; β = -0.39, q < 0.001) and cortisol response following a relocation stressor (Sample 1; β = -0.33, q < 0.001). We conclude that biobehavioral stress responsiveness may correlate with the developing epigenome, and that DNA methylation of immune cells may be a mechanism by which patterns of stress response affect health and immune functioning.

Neuroimaging and DNA Methylation: An Innovative Approach to Study the Effects of Early Life Stress on Developmental Plasticity

DNA methylation plays a key role in neural cell fate and provides a molecular link between early life stress and later-life behavioral phenotypes. Here, studies that combine neuroimaging methods and DNA methylation analysis in pediatric population with a history of adverse experiences were systematically reviewed focusing on: targeted genes and neural correlates; statistical models used to examine the link between DNA methylation and neuroimaging data also considering early life stress and behavioral outcomes. We identified 8 studies that report associations between DNA methylation and brain structure/functions in infants, school age children and adolescents faced with early life stress condition (e.g., preterm birth, childhood maltreatment, low socioeconomic status, and less-than optimal caregiving). Results showed that several genes were investigated (e.g., OXTR, SLC6A4, FKBP5, and BDNF) and different neuroimaging techniques were performed (MRI and f-NIRS). Statistical model used ranged from correlational to more complex moderated mediation models. Most of the studies (n = 5) considered DNA methylation and neural correlates as mediators in the relationship between early life stress and behavioral phenotypes. Understanding what role DNA methylation and neural correlates play in interaction with early life stress and behavioral outcomes is crucial to promote theory-driven studies as the future direction of this research fields.

Negative affectivity moderated by preterm birth predicted toddlers' behavior problems

OBJECTIVE

The present study aimed to examine the predictive effect of temperament moderated by preterm childbirth on behavioral problems in toddlerhood.

METHOD

The sample comprised 100 toddlers of 18-36 months of chronological age and their mothers. They were divided into two groups: 50 toddlers born preterm and admitted to the Neonatal Intensive Care Unit (PT group), and 50 toddlers born full-term (FT group) and recruited from day-care centers. Mothers completed questionnaires about toddlers' temperament and behavior. The Early Childhood Behavior Questionnaire was used to assess temperament, and the Child Behavior Checklist (CBCL 1¹/²-5) to evaluate the total, internalizing, and externalizing behavior problems. Multiple regression analysis was performed to examine the moderation effects of preterm childbirth and temperament factors after controlling for toddlers' age and socioeconomic level.

RESULTS

There was a moderation effect between preterm childbirth and temperament. Temperament with more Negative Affectivity, moderated by preterm birth, and less Effortful Control explained the total, internalizing, and externalizing behavior problems.

CONCLUSION

The findings contribute to a better understanding of the impact of preterm childbirth and the dispositional traits of temperament on behavioral problems of toddlers born preterm.

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.

Measuring the Outcomes of Maternal COVID-19-related Prenatal Exposure (MOM-COPE): study protocol for a multicentric longitudinal project

INTRODUCTION

COVID-19 is a highly infectious respiratory disease that rapidly emerged as an unprecedented epidemic in Europe, with a primary hotspot in Northern Italy during the first months of 2020. Its high infection rate and rapid spread contribute to set the risk for relevant psychological stress in citizens. In this context, mother-infant health is at risk not only because of potential direct exposure to the virus but also due to high levels of stress experienced by mothers from conception to delivery. Prenatal stress exposure associates with less-than-optimal child developmental outcomes, and specific epigenetic mechanisms (eg, DNA methylation) may play a critical role in mediating this programming association.

METHODS AND ANALYSIS

We present the methodological protocol for a longitudinal, multicentric study on the behavioural and epigenetic effects of COVID-19-related prenatal stress in a cohort of mother-infant dyads in Northern Italy. The dyads will be enrolled at 10 facilities in Northern Italy. Saliva samples will be collected at birth to assess the methylation status of specific genes linked with stress regulation in mothers and newborns. Mothers will provide retrospective data on COVID-19-related stress during pregnancy. At 3, 6 and 12 months, mothers will provide data on child behavioural and socioemotional outcomes, their own psychological status (stress, depressive and anxious symptoms) and coping strategies. At 12 months, infants and mothers will be videotaped during semistructured interaction to assess maternal sensitivity and infant's relational functioning.

ETHICS AND DISSEMINATION

This study was approved by the Ethics Committee (Pavia). Results will be published in peer-reviewed journals and presented at national and international scientific conferences.

TRIAL REGISTRATION NUMBER

NCT04540029; Pre-results.

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.

Serious neonatal morbidities are associated with differences in DNA methylation among very preterm infants

Background

Infants born very preterm are more likely to experience neonatal morbidities compared to their term peers. Variations in DNA methylation (DNAm) associated with these morbidities may yield novel information about the processes impacted by these morbidities.

Methods

This study included 532 infants born < 30 weeks gestation, participating in the Neonatal Neurobehavior and Outcomes in Very Preterm Infants study. We used a neonatal morbidity risk score, which was an additive index of the number of morbidities experienced during the NICU stay, including bronchopulmonary dysplasia (BPD), severe brain injury, serious neonatal infections, and severe retinopathy of prematurity. DNA was collected from buccal cells at discharge from the NICU, and DNAm was measured using the Illumina MethylationEPIC. We tested for differential methylation in association with the neonatal morbidity risk score then tested for differentially methylated regions (DMRs) and overrepresentation of biological pathways.

Results

We identified ten differentially methylated CpGs (α Bonferroni-adjusted for 706,278 tests) that were associated with increasing neonatal morbidity risk scores at three intergenic regions and at HPS4, SRRD, FGFR1OP, TNS3, TMEM266, LRRC3B, ZNF780A, and TENM2. These mostly followed dose–response patterns, for 8 CpGs increasing DNAm associated with increased numbers of morbidities, while for 2 CpGs the risk score was associated with decreasing DNAm. BPD was the most substantial contributor to differential methylation. We also identified seven potential DMRs and over-representation of genes involved in Wnt signaling; however, these results were not significant after Bonferroni adjustment for multiple testing.

Conclusions

Neonatal DNAm, within genes involved in fibroblast growth factor activities, cellular invasion and migration, and neuronal signaling and development, are sensitive to the neonatal health complications of prematurity. We hypothesize that these epigenetic features may be representative of an integrated marker of neonatal health and development and are promising candidates to integrate with clinical information for studying developmental impairments in childhood.

Adverse childhood experiences, epigenetics and telomere length variation in childhood and beyond: a systematic review of the literature

A systematic review following PRISMA guidelines was conducted to answer the question: What epigenetic, telomeric and associated biological changes are associated with exposure to adverse childhood experiences (ACEs) in the under 12s? Using PRISMA guidelines, appropriate databases were searched. 190 papers were returned with 38 articles fully reviewed. Articles were each independently quality rated by two authors using the Crowe Critical Appraisal Tool and data were extracted. Of the 38 articles, 23 were rated as very high quality. Most study participants were adults (n = 7769) with n = 727 child participants. Only seven of the very/high-quality studies were prospective and involved children. Methylation was the most studied method of epigenetic modification. There is some evidence supporting epigenetic modification of certain markers in participants exposed to ACEs measured in adulthood. Research is lacking on non-coding aspects of the epigenome and on coding aspects other than DNA methylation. There is some evidence of a more powerful effect on telomere length if physical neglect was involved. Much further work is required to model biological and psychological effects of epigenetic changes during childhood using prospective study designs. The effect of ACEs on the cellular ageing process during childhood is inadequately investigated and relies solely on measure of telomere length. Future research suggestions are proposed.

At the intersection of science and theory: How the Nurse Role Integration Model reconciles the conflict

As more nurses embrace precision science, there is a tendency to utilize theoretical frameworks from other disciplines thus, placing nursing at risk of losing its autonomy and independence. The discipline has fallen prey to internal binary opposition, eliminating opportunities to engage in civil discourse. To explore how the roles nurses select might fit together in a theoretical framework and help nurses understand how the roles they choose to support their identity as nurses, this paper introduced a model of nursing that includes the bench scientists, the policy activists, and bedside nurses, using the Neuman Systems Model (NSM). The Nurse Role Integration Model (NRIM) espouses the basic tenets of NSM: prevention counteracts stressors from penetrating the client’s lines of defense thus, reducing stress response. Primary prevention reflects the work of the nurse bench scientists, investigating the underlying mechanisms behind pathophysiology; secondary prevention is applied nurse scientists who build upon nurse researchers’ work, identifying and testing potential interventions; tertiary prevention is nurse policy activists, the fulcrum, who leverage primary and secondary findings to argue policy change at all levels. Once policy change is adopted, bedside nurses are educated and implement the change. This lens provides an opportunity to create greater solidarity, strengthening the unity and autonomy of the discipline.

Pain-related increase in serotonin transporter gene methylation associates with emotional regulation in 4.5-year-old preterm-born children

AIM

The main goal of this study was to assess the association between pain-related increase in serotonin transporter gene (SLC6A4) methylation and emotional dysregulation in 4.5-year-old preterm children compared with full-term matched counterparts.

METHODS

Preterm (n = 29) and full-term (n = 26) children recruited from two Italian hospitals were followed-up from October 2011 to December 2017. SLC6A4 methylation was assessed from cord blood at birth from both groups and peripheral blood at discharge for preterm ones. At 4.5 years, emotional regulation (ie, anger, fear and sadness) was assessed through an observational standardised procedure.

RESULTS

Preterm children (18 females; mean age = 4.5, range = 4.3-4.8) showed greater anger display compared with full-term controls (14 females; mean age = 4.5, range = 4.4-4.9) in response to emotional stress. Controlling for adverse life events occurrence from discharge to 4.5 years and SLC6A4 methylation at birth, CpG-specific SLC6A4 methylation in the neonatal period was predictive of greater anger display in preterm children but not in full-term ones.

CONCLUSION

These findings contribute to highlight how epigenetic regulation of serotonin transporter gene in response to NICU pain exposure contributes to long-lasting programming of anger regulation in preterm children.

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.

Temperamental Development among Preterm Born Children. An RCT Follow-Up Study

A randomized controlled trial study recruited 146 preterm born children, either to participate in a modified version of the Mother–Infant Transaction Program (MITP-m) or to receive the usual follow-up services, before and after discharge from a neonatal intensive care unit. This follow-up study investigates whether MITP participation is associated with parental perceptions of child temperament from two to seven years. Children’s temperament was reported by mothers and fathers separately at children’s ages of 2, 3, 5, and 7 years. Parents in the MITP-m group reported lower levels of negative emotionality in their children compared to the control group. In maternal reports, a group effect (F(1, 121) = 9.7, p = 0.002) revealed a stable difference in children’s negative emotionality from two to seven years, while a group-by-time interaction related to an increasing difference was detected in reports from fathers (F(1, 94) = 4.8, p = 0.03). Another group difference appeared in fathers’ reports of children’s soothability (F(1, 100) = 14.2, p < 0.0005). MITP-m fathers seemed to perceive their children as easier to soothe at all ages as no interaction with time appeared. Parental reports on children’s sociality, shyness, and activity did not differ between the groups.

Does preterm birth affect child temperament? A meta-analytic study

The present meta-analytic study was conducted to examine differences in temperament between preterm and full-term children, considering behavior style and psychobiological approaches. Moreover, we explored the potential moderators of the associations between prematurity and temperament. A systematic literature search was performed on PubMed, Scopus, Web of Science, and CINAHL. Twenty-two studies were analyzed. Preterm children showed a higher Activity level as well as lower Attentional Focusing and Attention Span/Persistence, in comparison with their full-term counterparts. Extremely preterm children showed a higher Activity level than other preterm levels. These findings support the conclusion that preterm children present with a less regulated temperament relative to those born full term.

[Research advances in the effect of environmental stress in the neonatal intensive care unit on the neurodevelopment of preterm infants and its epigenetics]

Adverse environmental stimulation in the neonatal intensive care unit (NICU) can affect neurodevelopment through epigenetic modification and thus has adverse effects on the long-term developmental outcome of preterm infants. Developmental care can reverse epigenetic changes in genes and promote neurodevelopment in preterm infants. This article reviews the influence of environmental stress in the NICU and developmental care on neurodevelopment in preterm infants, as well as related epigenetic effects, in order to provide a reference for epigenetic studies of preterm infants.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The effect of tub bathing and sponge bathing on neonatal comfort and physiological parameters in late preterm infants: A randomized controlled trial

BACKGROUND

Increasing comfort and physiological stabilization in preterm infants during neonatal care improves their neurophysiological development. Bathing procedures that support this development and will not expose the newborn to stress should be preferred.

OBJECTIVES

Our study aimed to examine the effectiveness of tub bathing and sponge bathing methods on the physiological parameters (i.e., heart rate, respiration rate, oxygen saturation, body temperature) and comfort of late preterm infants.

DESIGN

Randomized controlled trial. Study is registered at ClinicalTrials.gov NCT03796312.

SETTINGS

The trial was conducted in a neonatal intensive care unit of a university hospital in Antalya, Turkey.

METHODS

Late preterm infants (gestational age between 34 0/7 weeks and 36 6/7 weeks) were randomly assigned by a computer program to either intervention (tub bath) or control group (sponge bath). The physiological parameters and comfort of preterm infants in both groups were evaluated at 10 min before the bath. Infant comfort was reevaluated 10 min after the procedure, while physiological parameters were reevaluated after 15 and 30 min. Preterm infant heart rate, oxygen saturation, respiratory rate, body temperature and comfort behaviors were assessed by two independent evaluators who were blinded to the purpose of the study at different phases across the two bathing protocols. Written consent was obtained from the university and hospital ethics committee where the research was performed, and from the families of the infants participating in the study. SPSS 20.0 and SAS 9.3 were used for data analysis. Data was analyzed by percentage distribution, mean, repeated analysis, variance analysis, Bonferroni analysis as a further analysis and t-test in dependent groups.

RESULTS

Approximately 120 preterm infants completed the protocol (60 in each group). The two groups did not differ in gestational age, sex, weight or other demographic variables (p > 0.05). Tub bathing was more effective in reducing preterm infants' comfort scores (9.47 ± 2.55 vs. 14.85 ± 4.77, p < 0.001) and heart rate than sponge bathing (132.88 ± 12.00 vs. 144.00 ± 17.74, p < 0.05). Preterm infants in the tub bathing group maintained their body temperature better than those in the sponge bathing group (36.75 ± 0.26 vs. 36.59 ± 0.25, p < 0.05). There was no difference in oxygen saturation (98.35 ± 0.88 vs. 97.85 ± 1.36, p = 0.291) or respiratory rate (45.57 ± 5.39 vs. 47.20 ± 5.41, p = 0.472) between the tub and sponge bathing groups.

CONCLUSIONS

Tub bathing is a safer, more pleasurable/comfortable bathing option and is the recommended method for bathing healthy, late preterm infants.

Epigenome-wide Analysis Identifies Genes and Pathways Linked to Neurobehavioral Variation in Preterm Infants

Neonatal molecular biomarkers of neurobehavioral responses (measures of brain-behavior relationships), when combined with neurobehavioral performance measures, could lead to better predictions of long-term developmental outcomes. To this end, we examined whether variability in buccal cell DNA methylation (DNAm) associated with neurobehavioral profiles in a cohort of infants born less than 30 weeks postmenstrual age (PMA) and participating in the Neonatal Neurobehavior and Outcomes in Very Preterm Infants (NOVI) Study (N = 536). We tested whether epigenetic age, age acceleration, or DNAm levels at individual loci differed between infants based on their NICU Network Neurobehavioral Scale (NNNS) profile classifications. We adjusted for recruitment site, infant sex, PMA, and tissue heterogeneity. Infants with an optimally well-regulated NNNS profile had older epigenetic age compared to other NOVI infants (β₁ = 0.201, p-value = 0.026), but no significant difference in age acceleration. In contrast, infants with an atypical NNNS profile had differential methylation at 29 CpG sites (FDR < 10%). Some of the genes annotated to these CpGs included PLA2G4E, TRIM9, GRIK3, and MACROD2, which have previously been associated with neurological structure and function, or with neurobehavioral disorders. These findings contribute to the existing evidence that neonatal epigenetic variations may be informative for infant neurobehavior.

Associations between preterm infant stress, epigenetic alteration, telomere length and neurodevelopmental outcomes: A systematic review

BACKGROUND

Every year, an estimated 15 million babies are born preterm (<37 weeks' gestational age [GA]) globally. These preterm infants are exposed to repeated stressful and often painful procedures as part of routine life-saving care within the neonatal intensive care unit (NICU). Preterm birth continues to be a major health issue associated with increased risk of neurodevelopmental and behavioral disorders such as cerebral palsy, cognitive impairment, autism spectrum disorders and psychiatric disease.

OBJECTIVE

This paper identifies epigenetic alterations and incidence of telomere erosion that have been studied in preterm infants while in the NICU and as a long-term outcome measure. Better understanding of epigenetic alterations and telomere erosion might aid in early detection and prevention/alleviation of the negative effects of cumulative painful/stressful experiences in this population.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards were used to guide this review. Systematic searches of databases included PubMed, CINAHL, SCOPUS and PsychInfo.

RESULTS

Twenty-one studies were included, appraised and then synthesized into a narrative summary.

DISCUSSION

Several putative epigenetic markers were identified although there was a paucity of studies related to telomere length. The interaction of disease entity combined with therapeutic interventions intended to treat may inadvertently increase infant allostatic load or ability to adapt to stress. Future research should include not only human studies but leverage newly available large data sets to conduct additional analysis.

Epigenetic variation at the SLC6A4 gene promoter in mother-child pairs with major depressive disorder

BACKGROUND

Genetic and epigenetic variations of the serotonin transporter gene (SLC6A4) have been related to the etiology of depression. The 5-HTTLPR polymorphism at the SLC6A4 promoter region has two variants, a short allele (S) and a long allele (L), in which the S allele results in lower gene transcription and has been associated with depression. The short S-allele of 5-HTTLPR polymorphism of this gene has been associated with depression. In addition to molecular mechanisms, exposure to early life risk factors such as maternal depression seems to affect the development of depression in postnatal life. The present study investigated the association of 5-HTTLPR polymorphism and CpG DNA methylation (5mC) levels of an AluJb repeat element at the SLC6A4 promoter region in mother-child pairs exposed to maternal depression.

METHODS

We analyzed DNA samples from 60 subjects (30 mother-child pairs) split into three groups, with and without major depression disorder (DSM-IV) among children and mothers. The genotyping of 5-HTTLPR polymorphism and quantification of 5mC levels was performed by qualitative PCR and methylation-sensitive restriction enzyme digestion, and real-time quantitative PCR (MSRED-qPCR), respectively.

RESULTS

The sample analyzed presented a higher frequency of S allele of 5-HTTLPR (67.5%). Despite the high frequency of this allele, we did not find statistically significant differences between individuals carrying at least one S allele between the depression and healthy control subjects, or among the mother-child pair groups with different patterns of occurrence of depression. In the group where the mother and child were both diagnosed with depression, we found a statistically significant decrease of the 5mC level at the SLC6A4 promoter region.

LIMITATIONS

The limitations are the relatively small sample size and lack of gene expression data available for comparison with methylation data.

CONCLUSION

In this study, we demonstrated a repeat element specific 5mC level reduction in mother-child pairs, concordant for the diagnosis of depression.

Telomere length and salivary cortisol stress reactivity in very preterm infants

During the Neonatal Intensive Care Unit (NICU) stay, very preterm (VPT) infants are exposed to life-saving yet pain-inducing skin-breaking procedures (i.e., NICU pain-related stress) which contribute to the programming of hypo-responsive HPA axis development during the first months of life. Unfortunately, to date the mechanisms linking NICU pain-related stress and altered HPA axis regulation are only limitedly known. Telomere length (TL) regulation is an epigenetic mechanism previously shown to be affected by early stress exposures and capable of associating with HPA axis reactivity in children. In VPT infants, NICU pain-related stress was found to associate with decreased TL from birth to discharge, but there is no evidence for the association between TL and HPA axis in these infants. In this study, we prospectively examined the relationship between NICU pain-related stress and HPA axis reactivity to an age-appropriate socio-emotional condition (i.e., the Still-Face Procedure, SFP) in healthy VPT infants at 3-month corrected age. NICU pain-related stress was computed as the ratio between the number of skin-breaking procedures and length of NICU stay. A differential score (i.e., ∆TL) was obtained subtracting TL at birth from TL at discharge. A normalized (log10) cortisol reactivity index (CRI) was obtained by averaging post-stress (20 min after SFP) salivary cortisol sample on baseline value. A regression model controlling for neonatal and socio-demographic confounders showed that ∆TL was the only significant predictor of CRI. Although preliminary, these findings contribute to our knowledge of the mechanisms linking early exposures to adversity and later in life regulation of the HPA axis in VPT infants.

Epigenetic Signature of Chronic Maternal Stress Load During Pregnancy Might be a Potential Biomarker for Spontaneous Preterm Birth

Preterm birth is the leading cause of mortality in newborn infants and can lead to significant neonatal morbidities. Spontaneous preterm birth accounts for at least 50.0% of all preterm births. We argue that chronic maternal stress load, which is an important risk factor for spontaneous preterm birth, could be represented by epigenetic signature of several specific genetic loci in the mother’s blood. A literature search was done in PubMed with the following keywords: “DNA methylation,” “epigenetics,” “maternal stress” and “preterm birth” from year 2000 to 2017. We suggest that these genetic loci might be related to vulnerability and hypersensibility of stress response during pregnancy in women with preterm births. The mother’s epi-genetic stress bioprofile was supposed to be a result of chronic maternal stress load since her birth. This epigenetic bioprofile might also be a potential biomarker for spontaneous preterm birth. DNA methylation changes are tissue-specific and human stress response manifests mostly through the central nervous system (CNS). Nevertheless, we found evidence that methylation changes of DNA isolated from blood leucocytes might be a reliable measure of stress-related epigenetic changes that occur in the CNS. Evaluating biological mechanisms through the development of simple assays based on epigenetic changes to measure chronic stress loads in expectant mothers can lead to our ability to prepare more effective measures for the prevention of preterm births, as well as leading to more effective treatment strategies for both expectant mothers and their newborns.

The biological embedding of neonatal stress exposure: A conceptual model describing the mechanisms of stress-induced neurodevelopmental impairment in preterm infants

The biological embedding of early life stress exposure may result in life-long neurodevelopmental impairment in preterm infants. Infants hospitalized in the neonatal intensive care unit are exposed to significant experiential, environmental, and physiologic stressors over the course of their extended hospitalization. Stress exposure during the sensitive period of brain development may alter biological processes, including functioning of the immune system, the autonomic nervous system, and the hypothalamic-pituitary-adrenal axis as well as gene expression. These alterations may subsequently affect brain structure and function. Changes to these processes may mediate the relationship between neonatal stress exposure and neurodevelopment in preterm infants and represent potential therapeutic targets to improve long-term outcomes. The purpose of this paper is to introduce a conceptual model, based on published research, that describes the mechanisms mediating stress exposure and neurodevelopment impairment in preterm infants and to provide the theoretical foundation on which to base future descriptive research, intervention studies, and clinical care.

Methodological Challenges in Developmental Human Behavioral Epigenetics: Insights Into Study Design

Developmental human behavioral epigenetics (DHBE) holds potential for contributing to better understanding of how early life exposures contribute to human developmental trajectories and to inform clinical practice and early interventions. Nonetheless, DHBE research to date is challenged by two major issues: (a) the frequent use of retrospective study designs; and (b) the major focus on epigenetic variations associated with early life adversities, rather than protective care exposures. In order for DHBE research to maintain its promises, these issues need to be addressed in a systematic way according to a careful methodological planning of study design. In this contribution, we provide pragmatic insights on methodological aspects that should be dealt with while designing DHBE studies. We propose different study designs for the retrospective and prospective investigation of both adversity- and care-related epigenetic variations. Examples from available scientific literature are provided to better describe the advantages and the limitations of each study design.

Prenatal influences on temperament development: The role of environmental epigenetics

This review summarizes current knowledge and outlines future directions relevant to questions concerning environmental epigenetics and the processes that contribute to temperament development. Links between prenatal adversity, epigenetic programming, and early manifestations of temperament are important in their own right, also informing our understanding of biological foundations for social-emotional development. In addition, infant temperament attributes represent key etiological factors in the onset of developmental psychopathology, and studies elucidating their prenatal foundations expand our understanding of developmental origins of health and disease. Prenatal adversity can take many forms, and this overview is focused on the environmental effects of stress, toxicants, substance use/psychotropic medication, and nutrition. Dysregulation associated with attention-deficit/hyperactivity-disruptive disorders was noted in the context of maternal substance use and toxicant exposures during gestation, as well as stress. Although these links can be made based on the existing literature, currently few studies directly connect environmental influences, epigenetic programming, and changes in brain development/behavior. The chain of events starting with environmental inputs and resulting in alterations to gene expression, physiology, and behavior of the organism is driven by epigenetics. Epigenetics provides the molecular mechanism of how environmental factors impact development and subsequent health and disease, including early brain and temperament development.

Very preterm birth is associated with PLAGL1 gene hypomethylation at birth and discharge

AIM

Recent findings show that DNA methylation is susceptible to very preterm (VPT) birth and to the experience of the early stay in the neonatal intensive care unit. The aim of the study was to compare PLAGL1 methylation between VPT and full-term (FT) infants at birth as well as between VPT infants at discharge and FT infants at birth.

METHODS

DNA was collected from cord blood of 56 VPT and 27 FT infants at birth and from peripheral blood in VPT infants at neonatal intensive care unit discharge. Sociodemographic and neonatal variables were considered.

RESULTS

PLAGL1 methylation at birth and at discharge were highly correlated in VPT infants. Lower methylation emerged in VPT infants at birth and discharge compared to FT counterparts.

CONCLUSION

PLAGL1 hypomethylation emerged as a potential epigenetic mark of VPT birth. Future research is warranted to assess the functional consequences of PLAGL1 diminished methylation in VPT infants' development.

Incorporating epigenetic mechanisms to advance fetal programming theories

Decades of fetal programming research indicates that we may be able to map the origins of many physical, psychological, and medical variations and morbidities before the birth of the child. While great strides have been made in identifying associations between prenatal insults, such as undernutrition or psychosocial stress, and negative developmental outcomes, far less is known about how adaptive responses to adversity regulate the developing phenotype to match stressful conditions. As the application of epigenetic methods to human behavior has exploded in the last decade, research has begun to shed light on the role of epigenetic mechanisms in explaining how prenatal conditions shape later susceptibilities to mental and physical health problems. In this review, we describe and attempt to integrate two dominant fetal programming models: the cumulative stress model (a disease-focused approach) and the match-mismatch model (an evolutionary-developmental approach). In conjunction with biological sensitivity to context theory, we employ these two models to generate new hypotheses regarding epigenetic mechanisms through which prenatal and postnatal experiences program child stress reactivity and, in turn, promote development of adaptive versus maladaptive phenotypic outcomes. We conclude by outlining priority questions and future directions for the fetal programming field.

Pain exposure associates with telomere length erosion in very preterm infants

Very preterm (VPT) infants (gestational age < 32 weeks) require long-lasting hospitalization in the Neonatal Intensive Care Unit (NICU), even in absence of severe morbidities. During NICU stay, life-saving interventions occur and include invasive and painful skin-breaking procedures (NICU-related stress), which constitute a major early adverse experience for VPT infants. Telomeres are repeat-sequence at the end of chromosomes, which shorten with age and are highly susceptible to life adversities: the exposure to early adverse experiences is associated with shorter telomere length (TL). Nonetheless, previous research did not assess longitudinally the association between NICU-related stress and TL in VPT infants. In the present study, leukocyte TL was assessed from cord blood at birth in 46 VPT infants and in a group of 31 full-term (FT) infants, as well as at NICU discharge in VPTs only. NICU-related stress was measured as the number of skin-breaking procedures occurring throughout the NICU stay. A significant difference emerged for TL between VPT infants and FT counterparts at birth. TL decreased from birth to discharge in VPT infants, although the change was not significant in the group as a whole. The amount of NICU-related stress emerged as the primary predictor of TL erosion in VPT infants, even controlling for neonatal and clinical confounders. Furthermore, VPT infants exposed to high NICU-related stress exhibited a marked and significant decrease in TL, whereas VPT exposed to low NICU-related stress exhibited a non-significant increase. The present study confirms previous evidence of longer telomeres in VPT infants at birth compared to FT controls. Moreover, NICU-related stress emerged as a key regulator of TL erosion from birth to discharge in VPT infants. Future research is warranted to further explore TL erosion in VPT infants and the factors associated with individual differences in NICU-related stress susceptibility at the epigenetic level.