Paths of cognitive and language development in healthy preterm infants

Etiology of Borderline Intellectual Functioning

Borderline intellectual functioning (BIF), characterized by intelligence quotient scores between 70 and 85, can lead to challenges in daily life. This review explored the multifaceted nature of BIF by examining the interplay between genetic predisposition, prenatal/perinatal factors, environmental influences, and underlying medical conditions.

Through Thick and Thin: Gesture and Speech Remain as an Integrated System in Atypical Development

Gesture and speech are tightly linked and form a single system in typical development. In this review, we ask whether and how the role of gesture and relations between speech and gesture vary in atypical development by focusing on two groups of children: those with peri- or prenatal unilateral brain injury (children with BI) and preterm born (PT) children. We describe the gestures of children with BI and PT children and the relations between gesture and speech, as well as highlight various cognitive and motor antecedents of the speech-gesture link observed in these populations. We then examine possible factors contributing to the variability in gesture production of these atypically developing children. Last, we discuss the potential role of seeing others' gestures, particularly those of parents, in mediating the predictive relationships between early gestures and upcoming changes in speech. We end the review by charting new areas for future research that will help us better understand the robust roles of gestures for typical and atypically-developing child populations.

The relationship between neonatal stress in preterm infants and developmental outcomes at the corrected age of 24-30 months

Aim

The aim of research was to study the relationship between the stress experienced by preterm infants in the neonatal intensive care unit (NICU) and developmental status in the follow up, and to establish factors, associated with their neurodevelopment.

Methods

The first stage of research involved measuring stress markers (cortisol, melatonin) in infants (n = 56) during their NICU stay; the second phase assessed the developmental status at the corrected age of 24-30 months.

Results

The total ASQ-3 score, communication, problem solving, and personal-social skills scores at the corrected age of 24-30 months were positively correlated with melatonin level determined in the neonatal period (r = 0.31, p = 0.026; r = 0.36, p = 0.009; r = 0.30, p = 0.033, and r = 0.32; p = 0.022 respectively). In the same time, ASQ-3 communication and personal-social scores were negatively correlated with cortisol level (r = -0.31, p = 0.043; r = -0.35, p = 0.022). The ROC-curve analysis revealed that a decrease of melatonin below 3.44 ng/mL and 3.71 ng/mL during the neonatal period could predict communication and problem-solving delay, respectively. An increase in cortisol above 0.64 mcg/dl is predictive in personal-social delay. Negative correlation was identified between the NICU and total hospital stay duration and ASQ-3 communication scores in the follow-up (r = -0.27; p = 0.049 and r = -0.41; p = 0.002, respectively). The duration of mechanical ventilation was negatively correlated with gross motor scores (r = -0.46; p = 0.043). Apgar score was positively correlated with ASQ-3 communication (r = 0.29; p = 0.032) and personal-social scores (r = 0.28; p = 0.034); maternal age-with ASQ-3 total (r = 0.29; p = 0.034), communication (r = 0.37; p = 0.006), and personal-social scores (r = 0.29; p = 0.041). Positive correlations were observed between gestational age and communication scores (r = 0.28; p = 0.033). Infants who suffered neonatal sepsis had significantly often delay of communication (p = 0.014) and gross motor skills (p = 0.016). Children who required mechanical ventilation were more likely to have communication delay (p = 0.034).

Conclusion

Developmental outcomes in preterm infants at the corrected age of 24-30 months were associated with neonatal stress. Correlations between the communication, problem-solving and personal-social development in the follow up and cortisol and melatonin levels determined in the neonatal period supported this evidence. Factors as low gestational age, duration of hospital and NICU stay, mechanical ventilation, and sepsis were associated with more frequent delays in communication, gross motor and problems-solving skills.

Listening Preference for Child-Directed Speech Versus Time-Reversed Speech in Moderate-Preterm Infants Compared to Full-Term Infants

PURPOSE

The purpose of the present study was to examine whether there is a listening preference for child-directed speech (CDS) over backward speech in moderate-preterm infants (MPIs).

METHOD

Eighteen MPIs of gestational age of 32.0 weeks (range: 32-34.06 weeks), chronological age of 8.09 months, and maturation age of 6.48 months served as the experimental group. The two control groups consisted of a total of 36 infants-20 full-term infants matched for chronological age and 16 full-term infants matched for maturation age. The infants were tested using the central fixation procedure and were presented with 16 trials of CDS and backward speech. A follow-up was conducted 5 years after the initial experiment using a developmental and a five-item parent questionnaire.

RESULTS

MPIs did not demonstrate a preference for CDS over backward speech, whereas both control groups demonstrated a listening preference for CDS over backward speech. MPIs showed a delayed use of first words and word combinations and lower scores on the five-item questionnaire compared to term infants. Twelve MPIs (67%) did not demonstrate a preference for CDS over backward speech. Four of them (33%) were later diagnosed with neurodevelopmental disorders.

CONCLUSIONS

The lack of preference for CDS over backward speech in the MPIs group suggests delayed developmental pattern of speech processing compared to full-term peers. Delays in neurological maturation as well as listening experience in an unregulated environment outside the uterus during a sensitive period of brain development may affect the recognition of phonological and prosodic patterns that support listening preference for speech over backward speech.

What risk factors for Developmental Language Disorder can tell us about the neurobiological mechanisms of language development

Language is a complex multidimensional cognitive system that is connected to many neurocognitive capacities. The development of language is therefore strongly intertwined with the development of these capacities and their neurobiological substrates. Consequently, language problems, for example those of children with Developmental Language Disorder (DLD), are explained by a variety of etiological pathways and each of these pathways will be associated with specific risk factors. In this review, we attempt to link previously described factors that may interfere with language development to putative underlying neurobiological mechanisms of language development, hoping to uncover openings for future therapeutical approaches or interventions that can help children to optimally develop their language skills.

Effect of medically assisted reproduction (MAR) and pregnancy planning on Bayley-III Screening Test subscales in preterm infants at 12 months of corrected age: a cross-sectional study

Background

The association between medically assisted reproduction and pregnancy planning on overall developmental outcomes of infants has been studied in relatively few studies. The availability of accurate tools for the early detection of developmental delays is a major issue. The purpose of this study is describing the average neurodevelopment of preterm infants and assessing the association between medically assisted reproduction, pregnancy planning and neurodevelopmental outcomes among Hungarian preterm infants.

Methods

Cross-sectional study of preterm infants with gestational age < 37 weeks (N = 171) who underwent developmental assessment using Bayley-III Screening Test (Bayley Scales of Infant and Toddler Development Screening Test – Third Edition) in five developmental domains (cognitive, receptive and expressive language, fine and gross motor) at 12 months of corrected age. We examined the developmental pattern of infants and the potential associations between medically assisted reproduction, pregnancy planning and Bayley-III Screening Test subscales. Information on the mode of conception and pregnancy planning was obtained through parental anamnesis.

Results

Concerning the risk for developmental delay, the language and motor subscales were the most affected. Examination of the mode of conception and developmental outcomes revealed higher neurodevelopmental skills in infants who were conceived through medically assisted reproduction. Significantly lower cognitive, receptive and expressive language skills were found to be associated with unplanned pregnancies. Multi-way analysis of variance was conducted in order to assess the impact of the mode of conception and pregnancy planning on subscales.

Conclusions

We cannot unambiguously conclude that MAR and pregnancy planning had a solely positive effect on the development of preterm infants at 12 months of corrected age, but our results are vital for the design and implementation of further research.

Semantic Contingency of Maternal Verbal Input Directed at Very Preterm and Full-Term Children

Several studies have testified to the importance of a responsive linguistic input for children’s language acquisition and development. In particular, maternal use of expansions, imitations, interpretations, and labels has been shown to promote both children’s language comprehension and production. From this perspective, the present study examined the semantically contingent linguistic input addressed to very preterm children’s comparing it to that directed to full-term children observed during a semi-structured play session when the children were 24 months of age. The relationships between maternal contingent utterances and children’s communicative repertoires were also investigated. The main results showed that mothers of full-term children produced a higher proportion of semantically contingent utterances than those of very preterm children; moreover, this variable was associated with children’s more advanced communicative-linguistic outcomes. Overall, this study supports the interdependence between mothers’ use of certain linguistic strategies and children’s communicative-linguistic repertoire, extending this evidence to children born very preterm and suggesting the importance of considering the semantic contingency aspect of child-directed speech to support the communicative and linguistic development of these children.

Monochorionic Twins and the Early Mother-Infant Relationship: An Exploratory Observational Study of Mother-Infant Interaction in the Post-Partum Period

The extraordinary increase in twin rates and specifically monochorionic twin pregnancies represents a major public health issue due to the associated increased risks for the mother, the child and their relationship. The aim of the present study was to examine the quality of mothers’ behaviour during mother–infant interaction in the early postpartum period by comparing mothers of twins and mothers of singletons during face-to-face interaction with their infants. Demographic and clinical information was collected by trained research psychologists from the mothers’ and the childrens’ clinical records and from interviews with the mothers. At three months (corrected for prematurity), the interactions of the dyads (11 mother-twin infant dyads and 11 mother-singleton dyads) were filmed at participants’ homes in accordance with the procedure of the Global Rating Scales. Maternal behaviour during interactions was assessed and rated by two trained research psychologists. With regard to the mothers’ interaction with each twin, no differences were found between mothers’ scores in every GRS subscale, indicating that mothers did not interact differently with their twins. Comparisons between mothers of MC twins and mothers of singletons showed that the quality of maternal sensitive behaviour during the interactions were lower in mothers of twins (0.35) Mothers of twins were also more distant during interactions with their babies and more likely to experience depression symptoms than mothers of singletons (0.05). Future research should examine mother-infant relationships following twin birth with larger samples. Such research will be especially useful in evaluating the potential benefits of interventions to promote positive mother-infant interactions.

Longitudinal Cognitive Assessment in Low-Risk Very Preterm Infants

Background and Objectives: Preterm infants are at higher risk of neurodevelopmental impairment both at preschool and school ages, even in the absence of major neurological deficits. The early identification of children at risk is essential for early intervention with rehabilitation to optimize potential outcomes during school years. The aim of our study is to assess cognitive outcomes at preschool age in a cohort of low-risk very preterm infants, previously studied at 12 and 24 months using the Griffiths scales. Materials and Methods: Sixty-six low-risk very preterm infants born at a gestational age of <32 weeks were assessed at 12 and 24 months corrected age using the Griffiths Mental Development Scales (second edition) and at preschool age with the Wechsler Preschool and Primary Scales of Intelligence (third edition) (WPPSI-III). Results: At 12 and 24 months and at preschool age, low-risk very preterm infants showed scores within normal ranges with similar scores in males and females. A statistically significant correlation was observed in the general developmental quotient between 12 and 24 months; a further significant correlation was observed between the early cognitive assessments and those performed at preschool age, with a better correlation using the assessments at 24 months. Conclusion: The present study showed a favourable trajectory of cognitive development in low-risk very preterm infants, from 12 months to preschool age.

Is premature birth an environmental sensitivity factor? A scoping review protocol

INTRODUCTION

Globally, around 10% of children are born preterm and are more at risk of negative developmental outcomes. However, empirical evidences and theoretical reasoning also suggest that premature birth can be a susceptibility factor, increasing sensitivity to the environment for better and for worse. Because available findings are controversial, with the current scoping review we will explore if, based on the available literature, preterm birth can be seen as an environmental sensitivity (ES) factor. In doing so, we will consider a series of moderating variables, including the level of prematurity, the type of environment and the outcome investigated. Methodological aspects, as the type of measures used and study design, will be considered.

METHODS AND ANALYSIS

The scoping review will be conducted following the Joanna Briggs Institute Methodology guidelines. The report will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews checklist. We will perform the search between 15 January 2022 and 1 February 2022. Data will be chartered by independent reviewers.

ETHICS AND DISSEMINATION

Ethical approval is not required, as primary data will not be collected. This scoping review will be the first to explore whether prematurity is associated with an increased ES. This review can have important implications for tailoring prevention and intervention programmes. Results will be published in a peer-reviewed journal.

Neurodevelopmental outcomes in preterm infants with retinopathy of prematurity

Over the past decade there has been a paradigm shift in the treatment of retinopathy of prematurity (ROP) with the introduction of antivascular endothelial growth factor (anti-VEGF) treatments. Anti-VEGF agents have the advantages of being easier to administer, requiring less anesthesia, having the potential for improved peripheral vision, and producing less refractive error than laser treatment. On the other hand, it is known that intravitreal administration of anti-VEGF agents lowers VEGF levels in the blood and raises the theoretical concern of intraocular anti-VEGF causing deleterious effects in other organ systems, including the brain. As a result, there has been increased attention recently on neurodevelopmental outcomes in infants treated with anti-VEGF agents. These studies should be put into context with what is known about systemic comorbidities, socioeconomic influences, and the effects of extreme prematurity itself on neurodevelopmental outcomes. We summarize what is known about neurodevelopmental outcomes in extremely preterm infants with ROP, discuss the implications for determining the neurodevelopmental status using neurodevelopmental testing as well as other indicators, and review the existing literature relating to neurodevelopmental outcomes in babies treated for ROP.

Neurodevelopmental outcome of preterm very low birth weight infants admitted to an Italian tertiary center over an 11-year period

Preterm very low birth weight infants (VLBWi) are known to be at greater risk of adverse neurodevelopmental outcome. Identifying early factors associated with outcome is essential in order to refer patients for early intervention. Few studies have investigated neurodevelopmental outcome in Italian VLBWi. The aim of our longitudinal study is to describe neurodevelopmental outcome at 24 months of corrected age in an eleven-year cohort of 502 Italian preterm VLBWi and to identify associations with outcome. At 24 months, Griffiths’ Mental Developmental Scales were administered. Neurodevelopmental outcome was classified as: normal, minor sequelae (minor neurological signs, General Quotient between 76 and 87), major sequelae (cerebral palsy; General Quotient ≤ 75; severe sensory impairment). 75.3% showed a normal outcome, 13.9% minor sequelae and 10.8% major sequelae (3.8% cerebral palsy). Male gender, bronchopulmonary dysplasia, abnormal neonatal neurological assessment and severe brain ultrasound abnormalities were independently associated with poor outcome on multivariate ordered logistic regression. Rates of major sequelae are in line with international studies, as is the prevalence of developmental delay over cerebral palsy. Analysis of perinatal complications and the combination of close cUS monitoring and neurological assessment are still essential for early identification of infants with adverse outcome.

Early Inflammatory Measures and Neurodevelopmental Outcomes in Preterm Infants

BACKGROUND

Inflammation may be an important predictor of long-term neurodevelopment in preterm infants. The identification of specific inflammatory biomarkers that predict outcomes is an important research goal.

OBJECTIVES

The purpose of this analysis was to identify associations between an early measure of inflammation and neurodevelopment in very preterm infants and to identify differences in the relationship between inflammation and neurodevelopment based on infant gender and race.

METHODS

We conducted a secondary analysis of data from a randomized controlled trial of a caregiving intervention for preterm infants born less than 33 weeks postmenstrual age. Plasma was collected with a clinically indicated laboratory draw by neonatal intensive care unit nurses and analyzed by multiplex assay for cytokines, chemokines, and growth factors. Neurobehavior was assessed by research nurses at the time of discharge from the neonatal intensive care unit using the motor development and vigor and alertness/orientation clusters from the Neurobehavioral Assessment of the Preterm Infant. Neurodevelopment was assessed at 6 months corrected age by the developmental specialist in the hospital's neonatal follow-up clinic using the Bayley Scales of Infant Development, Third Edition. We used linear regressions to estimate the effect of cytokine levels on neurodevelopment and allowed the effects to differ by infant gender and race.

RESULTS

In a sample of 62 preterm infants with discharge neurobehavioral assessments and a sample of 40 preterm infants with 6-month neurodevelopmental assessments, we found inconsistent associations between single-time point inflammatory measures and neurobehavior or neurodevelopment in analyses of the total sample. However, regressions with interactions revealed effects for multiple inflammatory measures on early neurobehavior and neurodevelopment that differed by infant gender and race.

DISCUSSION

Although early single-time point measures of inflammation may be insufficient to predict neurodevelopment for all preterm infants, the effect of inflammation appears to differ by infant gender and race. These demographic factors may be important considerations for future studies of inflammation and neurodevelopment as well was the development of future interventions to optimize outcomes.

Influence of perinatal complications on the development of a sample of 36-month-old premature infants

OBJECTIVE

The lack of clear results in previous studies for this context makes us consider an exploratory study. The objective of this research is to examine the influence of certain perinatal factors on the development of premature infants over their first 36 months of life.

METHOD

The sample consisted of 59 preterm infants born between 25 and 34 weeks of gestational age in an NICU of a third-level hospital. At 36 months of age, the Bayley-III Infant Development Scale (Spanish adaptation) and a clinical history were collected.

RESULTS

The average scores on the Bayley-III Infant Development Scale were generally within the normal range, but significantly lower than normal for Fine Motor Function, Gross Motor Function, and Expressive Language. These differences remained when considering the degree of prematurity, gender, and perinatal complications. Infants who received mechanical ventilation, oxygen therapy or corticosteroid treatment due to bronchopulmonary dysplasia showed the greatest discrepancies from normal levels.

CONCLUSION

Our results support prior studies that show that a combination of perinatal risk factors constitutes the largest determinant for developmental issues at 36 months of age. This information establishes the need for a priority follow-up in this population beyond 24 months of corrected age.

Toddlers' Language Development: The Gradual Effect of Gestational Age, Attention Capacities, and Maternal Sensitivity

Language development in toddlerhood forms the foundation for speech and language comprehension throughout childhood. Children born moderately preterm are at increased risk for problems in receptive and expressive language functioning, and they may need specific support or interventions. To understand the underlying mechanisms of language development, an integrated model of gestational age, attention capacities, and maternal sensitivity was examined in relation to receptive and expressive language functioning in toddlerhood. Our sample included 221 children (gestational age between 32–41 + 6 weeks; 54.7% born moderately preterm; 51.6% boys; 69.1% highly educated mothers). At 18 months (corrected age), attention capacities were measured using an eye-tracking procedure and maternal sensitivity was observed during mother-child interaction. Language was assessed at 24 months (corrected age). Results showed children with a higher gestational age scored higher on receptive language. This association was direct, as well as indirect through the child’s alerting attention. Expressive language was related to maternal sensitivity. Gestational age and alerting attention capacities specifically were related to language comprehension, whereas maternal sensitivity was related to speech. As language comprehension and speech in toddlerhood show different associations with biological, child, contextual, and regulation factors, they should be viewed as separate constructs in research and practice.

Inflammatory predictors of neurobehavior in very preterm infants

BACKGROUND

Preterm infants are at risk for impaired neurodevelopment. Inflammation may be an important modifiable mediator of preterm birth and neurodevelopmental impairment, but few studies have examined longitudinal measures of inflammation.

OBJECTIVE

To determine the relationship between longitudinal measures of inflammation and neurobehavior in very preterm infants.

STUDY DESIGN

Non-experimental, repeated measures cohort study.

METHODS

Very preterm infants were enrolled between October 2017 and December 2018. Blood was collected weekly until 35 weeks post-menstrual age for the quantification of plasma cytokines. Neurobehavior was assessed at 35 weeks post-menstrual age using the cluster scores for motor development and vigor and alertness/orientation from the Neurobehavioral Assessment of the Preterm Infant. Multiple linear regression models with robust standard errors were used to analyze the data. Average levels of individual cytokines, cytokine trends, and composite scores were used as measures of inflammation.

RESULTS

Seventy-three infants were enrolled in the study. Interleukin-1 receptor antagonist was associated with motor development and vigor scores. Interleukin-6 was associated with alertness/orientation scores. Tumor necrosis factor-alpha and composite scores of inflammation were associated with motor development and vigor and alertness/orientation scores. There were interactions with post-menstrual age at birth and infant sex.

CONCLUSION

Inflammation may be an important predictor of short-term neurobehavior in preterm infants. Interleukin-1 receptor antagonist, interleukin-6, and tumor necrosis factor-alpha are key cytokines for studies of preterm infants, but composite scores may be a better measure of inflammation than individual cytokines. Inflammation can be damaging to the immature brain and may be a specific target for future interventions to improve outcomes.

A new perspective: Establishing developmental profiles of premature infants based on Bayley-III scores at age 2

Longitudinal and cross-sectional studies in early childhood generally focus on different developmental areas separately. The aim of this study is to identify the most common developmental profiles regarding cognitive, language and motor skills among low birthweight (LBW) children. Our sample included 208 LBW children examined at 24-28 months. We used cluster analysis to identify developmental profiles based on the scores of the Bayley-III Cognitive, Language and Motor scales. We found three consistent profiles (High, Mildly Delayed and Severely Delayed) and three inconsistent, average profiles (with High Expressive Language, with Mildly Delayed Expressive Language and with Severely Delayed Language). Socioeconomic status, maternal education, in vitro fertilization, plurality and chronic morbidities were significantly related to the clusters. Cluster analysis might be an effective method to identify developmental profiles of preterm (and other at-risk) children, which might result in a more complex understanding of cognitive and psychomotor development in early childhood.

Developmental Dimensions in Preterm Infants During the 1st Year of Life: The Influence of Severity of Prematurity and Maternal Generalized Anxiety

BACKGROUND

The literature has recognized premature birth as a risk factor for infant development and maternal anxiety. This study investigated the impact of the severity of birth weight, as well as of maternal anxiety at 3 months of infants' corrected age, on infants' outcomes during the 1st year postpartum. Moreover, it described the longitudinal trajectories of developmental outcomes, additionally exploring the impact of anxiety.

METHODS

The study compared 147 mothers and their 147 newborns, differentiated in 25 Extremely Low Birth Weight (ELBW), 41 Very Low Birth Weight (VLBW), and 81 Full-Term (FT) infants. At 3, 9, and 12 months (corrected age in the case of preterm infants) the level of infants' development was investigated according to the 5 quotients (Locomotor, Personal and Social, Hearing and Language, Eye-hand Co-ordination and Performance) of the Griffiths Mental Development Scales (GMDS-R). During the assessment of 3 months, mothers fulfilled Penn State Worry Questionnaire (PSWQ) to evaluate the presence of generalized anxiety.

RESULTS

Among the 5 GMDS-R quotients, significant effect of severity of birth weight emerged only for Performance quotient: preterm infants (ELBW at 3 months; VLBW at 12 months) showed lower scores than FT ones. Moreover, this quotient decreased from 3 to 9 and to 12 months for VLBW and FT infants, while it was stable for ELBW ones. A significant interaction between severity of birth weight and maternal anxiety emerged for Hearing and Language and Locomotor quotients. In the first case, scores for ELBW infants, independently from maternal anxiety, decreased from 9 to 12 months. The same results emerged for VLBW infants, in the case of non-anxious mothers. Regarding Locomotor quotient, mean scores decreased from 3 to 9 and to 12 months for all groups in the case of non-anxious mothers. Conversely, when mothers were anxious, this decrease emerged only for VLBW infants. Lastly, ELBW, VLBW and FT showed difference in the growth and slope of the trajectories of different quotients.

CONCLUSION

The severity of birth weight for preterm infants, also in interaction with maternal anxiety, had significant and specific impact on different dimensions of infants' development. Clinical implications of these results underline the need for individualized interventions.

Birth weight, verbal cognition in early adolescence, and lexical and reading skills in late adolescence: a formal mediation analysis using a potential outcomes approach

BACKGROUND

Oral and written language in late adolescence are influenced by many pre- and postnatal factors, including cognitive performance at earlier ages. We investigated whether the association between birth weight and lexical knowledge and reading comprehension in late adolescence (14-16 years) is mediated by verbal cognition during early adolescence (10-11 years).

METHODS

We conducted a mediation analysis via a potential outcomes approach to data from three United Kingdom (UK) prospective birth cohorts - The National Child Development Study (NCDS; year of birth (Y.B.) = 1,958; analytic sample size (A.N.) = 9,399; original sample size (O.N.) = 18,558), British Cohort Study (BCS70; Y.B. = 1,970; A.N. = 6,591; O.N. = 17,196), and Millennium Cohort Study (MCS; Y.B. = 2,000-2,001; A.N. = 3,950; O.N. = 18,552) - to evaluate the indirect effects of birth weight on lexical knowledge (BCS and MCS) and reading comprehension measures (NCDS) in adolescence.

RESULTS

We found an indirect effect but no statistically significant direct effects for the BCS and MCS cohorts. The proportion of the effect of birth weight on oral and written language in late adolescence mediated by early adolescence verbal cognition was 59.19% (BCS) and 8.41% (MCS) for lexical knowledge and 61.00% when the outcome was reading comprehension (NCDS). Sensitivity analyses, used to assess whether unmeasured variables could have affected our mediation estimates, showed that for reading comprehension, in NCDS, the indirect effect is robust; only unmeasured confounders highly correlated with the mediator and outcome (ρ = .68) would explain away the indirect effect. For lexical knowledge, smaller correlations with hypothetical confounders (ρ = .33 for BCS) would suffice to render the indirect effect non-significant; the indirect effect for MCS non statistical significant.

CONCLUSIONS

Birth weight affects oral and written language skills (lexical knowledge and reading comprehension) in late adolescence via verbal cognition in early adolescence in two cohorts born in 1958 and 1970, but not in a cohort born at the turn of the millennium. These indirect effects were stronger than the direct effects and are unlikely to be explained by unmeasured confounders when the outcome involves complex skills such as reading comprehension.

Inflammatory mediators of stress exposure and neurodevelopment in very preterm infants: Protocol for the stress neuro-immune study

AIMS

(a) Determine relationships among stress exposure, inflammation, and neurodevelopment in very preterm infants and determine the mediated effect of inflammation on the relationship between stress exposure and neurodevelopment; (b) describe cytokine trajectories following birth and determine the effect of stress exposure on these trajectories; and (c) examine relationships between stress exposure and chronic stress responses in very preterm infants.

DESIGN

Non-experimental, repeated measures.

METHODS

Very preterm infants born 28-31 weeks post menstrual age will be enrolled. Cumulative stress exposure over the first 14 days of life will be measured using the Neonatal Infant Stressor Scale. Blood will be collected weekly for the quantification of cytokines. Neurodevelopment will be assessed using the Neurobehavioral Assessment of the Preterm Infant and hair for quantification of hair cortisol will be collected at 35 weeks post menstrual age. Multiple linear regression and conditional process analysis will be used to analyse the relationships among stress exposure, inflammation and neurodevelopment. Linear mixed models will be used to determine inflammatory trajectories over time. IRB approval for the study was received May 2017, and funding from the National Institute of Nursing Research was awarded July 2017.

DISCUSSION

This study will determine the extent to which inflammation mediates the relationship between stress exposure and neurodevelopment. Interventions to attenuate inflammation in preterm infants may improve outcomes.

IMPACT

Determining the potentially modifiable mediators of stress exposure and neurodevelopment in preterm infants is critical to improving long-term outcomes.

Stress and feelings in mothers and fathers in NICU: identifying risk factors for early interventions

AIMS

The aims of this study were to explore parents' stress levels and negative feelings after premature births and to identify the risk factors related to parents' stress and negative feelings during their children's neonatal intensive care unit (NICU) stay.

BACKGROUND

Preterm birth is a multi-problematic event that may put the babies in danger for both their medical and neurophysiological conditions and could have a negative impact on both the mother-father relationship and the parent-child interactions.

METHODS

The study involved 43 mothers and 38 fathers of preterm infants. All participants filled out the Parental Stressor Scale: Neonatal Intensive Care Unit and the Profile of Mood States.

FINDINGS

The results revealed significant differences between mothers' and fathers' responses to preterm births in terms of both stress and negative feelings. We found that, for mothers, their own young age and the baby's need for respiratory support were significant predictors of stress; for fathers, their own young age and the baby's lower gestational age and worse condition at birth were significant predictors of stress and negative feelings. The NICU may be a stressful place both for mothers and fathers. Identifying which mothers and fathers are at risk immediately after their children are born could help to direct specific interventions that can reduce these parents' stress and prevent them from negative feelings.

An Integrative Review of Cytokine/Chemokine Predictors of Neurodevelopment in Preterm Infants

Preterm infants are at risk of brain injury and poor neurodevelopmental outcomes including impairments in cognition, behavioral functioning, sensory perception, and motor performance. Systemic inflammation has been identified as an important, potentially modifiable precursor of neurologic and neurodevelopmental impairments. Inflammation is typically measured by quantifying circulating cytokines and chemokines. However, it is unclear which specific cytokines/chemokines most consistently predict neurodevelopment in preterm infants. In this integrative review, we evaluated and analyzed the literature (N = 37 publications) to determine the cytokines/chemokines most predictive of neurodevelopment in preterm infants, the optimal timing for these measurements, and the ideal source for collecting cytokines/chemokines. Synthesis of the findings of these studies revealed that interleukin (IL)-6, IL-1β, IL-8, and tumor necrosis factor (TNF)-α collected during the first 3 weeks of life are most predictive of subsequent neurodevelopment. Methodological variation among studies hinders more specific analysis, including the evaluation of cytokine thresholds and meta-analyses, that would allow for the use of cytokines/chemokines to predict neurodevelopment. Future research should focus on identifying explicit cytokine values, specifically for IL-6, IL-1β, IL-8, and TNF-α, that are most predictive for identifying preterm infants most at risk of impairment, keeping in mind that longitudinal measures of cytokines/chemokines may be more predictive of future outcomes than single-time point measures.

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.

Developmental assessment of preterm infants: Chronological or corrected age?

The aim of this study is to examine the effect of age correction on the developmental assessment scores of preterm infants, using for the first time, the Mullen scales of early learning (MSEL) test. Participants included 110 preterm infants (born at a gestational age of ≤ 34 weeks) at ages 1, 4, 8, 12, 18, 24 and 36 months. The corrected age-based MSEL composite score and each of the five MSEL scale scores were significantly higher than chronological age-based scores at all ages. These corrected scores were significantly higher than the chronological scores regardless of gestational age whether weight was, or adequate or small for gestational age. Larger differences between corrected and chronological age-based scores significantly correlated with earlier gestational age and with lower birth weight between 1 and 24 months but not at 36 months. Using chronological age-based scores yielded significantly more infants identified with developmental delays than using corrected age-based scores. The findings indicate that clinicians and researchers, as well as family members, should be aware of and acknowledge the distinction between corrected and chronological ages when evaluating preterm infants in research and clinical practices.

Developmental Outcomes, Attachment and Parenting: Study of a Sample of Spanish Premature Children

The aim of this study is to provide an overview of the development of premature children, including attachment, child psychological adjustment and parental variables. 130 children < 1,500 g or < 32 weeks at birth from two public hospitals, assessed at two years corrected age, together with their parents. Parental socio-demographic data was collected. Infant development, attachment and child psychological adjustment were evaluated, as was parental stress. The percentage of preterm children with developmental delays ranged from 5% to 21%. Girls tend to show higher levels of development than boys with effect sizes ranging from small, η2p = .02, to medium, η2p = .07. Secure attachment was the most frequent pattern in the sample. No significant differences, p < .05, between preterm children and the normative population were found on children´s behavioral problems and maternal stress levels. Despite the fact prematurity is considered to be a risk factor for a child´s development, a significant proportion of these children do not show problems in terms of developmental levels, attachment pattern and maternal stress. However, socio-emotional and affective domains, as well as psychological support programs for parenthood, should be followed up from a multidisciplinary perspective.

A Randomized Clinical Trial of Umbilical Cord Milking vs Delayed Cord Clamping in Preterm Infants: Neurodevelopmental Outcomes at 22-26 Months of Corrected Age

OBJECTIVE

To compare the effect of umbilical cord milking vs delayed cord clamping (DCC) on neurodevelopmental and health outcomes in very preterm infants at 22-26 months of corrected age.

STUDY DESIGN

Neurodevelopmental outcomes at 2 years of age were assessed using the Bayley Scales of Infant Development, third edition, and a standardized neurologic examination. Data regarding pulmonary morbidities, neurosensory impairments, and hospitalizations were obtained by parental interview. Intention-to-treat was used for primary analyses.

RESULTS

Of the 197 infants enrolled in the original study there were 15 deaths, 5 in the umbilical cord milking group and 10 in DCC group. Of the remaining infants, 135 (74%) were assessed at 22-26 months of corrected age. Demographics in umbilical cord milking (n = 70) and DCC (n = 65) groups were similar. Infants randomized to umbilical cord milking at birth had significantly higher cognitive and language composite scores, and were less likely to have a cognitive composite score of <85 (4% vs 15%; P = .04). Motor function was similar in both groups. There were no differences in the incidences of mild or moderate to severe neurodevelopmental impairment, hearing or visual impairments, pulmonary morbidities, or rehospitalizations between the 2 groups.

CONCLUSIONS

Infants randomized to umbilical cord milking had higher language and cognitive scores compared with those randomized to DCC. There was no difference in rates of mild or moderate to severe neurodevelopmental impairment.

TRIAL REGISTRATION

clinicaltrials.gov: NCT01434732.

Is level of prematurity a risk/plasticity factor at three years of age?

Children born preterm have poorer outcomes than children born full-term, but the caregiving environment can ameliorate some of these differences. Recent research has proposed that preterm birth may be a plasticity factor, leading to better outcomes for preterm than full-term infants in higher quality environments. This analysis uses data from two waves of an Irish study of children (at 9 months and 3 years of age, n=11,134 children) and their caregivers (n=11,132 mothers, n=9998 fathers) to investigate differences in how caregiving affects social, cognitive, and motor skills between full-term, late preterm, and very preterm children. Results indicate that parental emotional distress and quality of attachment are important for child outcomes. Both being born very preterm and late preterm continue to be risk factors for poorer outcomes at 3 years of age. Only fathers' emotional distress significantly moderated the effect of prematurity on infants' cognitive and social outcomes-no other interactions between prematurity and environment were significant. These interactions were somewhat in line with diathesis stress, but the effect sizes were too small to provide strong support for this model. There is no evidence that preterm birth is a plasticity factor.