Contingency Learning and Reactivity in Preterm and Full-Term Infants at 3 Months

Biological and environmental factors may affect children's executive function through motor and sensorimotor development: Preterm birth and cerebral palsy

Disruptive biological and environmental factors may undermine the development of children's motor and sensorimotor skills. Since the development of cognitive skills, including executive function, is grounded in early motor and sensorimotor experiences, early delays or impairments in motor and sensorimotor processing often trigger dynamic developmental cascades that lead to suboptimal executive function outcomes. The purpose of this perspective paper is to link early differences in motor/sensorimotor processing to the development of executive function in children born preterm or with cerebral palsy. Uncovering such links in clinical populations would improve our understanding of developmental pathways and key motor and sensorimotor skills that are antecedent and foundational for the development of executive function. This knowledge will allow the refinement of early interventions targeting motor and sensorimotor skills with the goal of proactively improving executive function outcomes in at-risk populations.

Anticipatory regulation of cardiovascular system on the emergence of auditory-motor interaction in young infants

Humans develop auditory-motor interaction to produce a variety of rhythmic sounds using body movements, which are often produced and amplified with tools, such as drumming. The extended production of sounds allows us to express a wide range of emotions, accompanied by physiological changes. According to previous studies, even young infants enhance movements in response to auditory feedback. However, their exhibition of physiological adaptation on the emergence of auditory-motor interaction is unclear. We investigated the movement and cardiac changes associated with auditory feedback to spontaneous limb movements in 3-month-old infants. The results showed that infants increased the frequency of limb movements inducing auditory feedback, while they exhibited a more regular rhythm of the limb movements. Furthermore, heart rate increase associated with the limb movement was first inhibited immediately after the timing of the auditory feedback, which may reflect sustained attention to the auditory stimuli. Then, through auditory-motor experience, the heart rate increase was inhibited even prior to the auditory feedback, leading to suppression of the peak intensity of the heart rate increase. These findings suggest that young infants regulate the cardiovascular system as well as limb movements in anticipation of the auditory feedback. The anticipatory regulation associated with movement and attentional changes may contribute to reduced cardiovascular stress in auditory-motor interaction, and provide a developmental basis for more sophisticated goal-directed behavior of producing rhythmic sounds.

A model for using developmental science to create effective early intervention programs and technologies to improve children's developmental outcomes

Children born with a variety of environmental or medical risk factors may exhibit delays in global development. Very often, such delays are identified at preschool or school age, when children are severely overdue for effective early interventions that can alleviate the delays. This chapter proposes a conceptual model of child development to inform the creation of interventions and rehabilitative technologies that can be provided very early in development, throughout the first year of life, to optimize children's future developmental outcomes. The model suggests that early sensorimotor skills are antecedent and foundational for future motor, cognitive, language, and social development. As an example, this chapter describes how children's early postural control and exploratory movements facilitate the development of future object exploration behaviors that provide enhanced opportunities for learning and advance children's motor, cognitive, language, and social development. An understanding of the developmental pathways in the model can enable the design of effective intervention programs and rehabilitative technologies that target sensorimotor skills in the first year of life with the goal of minimizing or ameliorating the delays that are typically identified at preschool or school age. Specific examples of early interventions and rehabilitative technologies that have effectively advanced children's motor and cognitive development by targeting early sensorimotor skills and behaviors are provided.

Infants born preterm and infants born full-term generate more selective leg joint movement during the scaffolded mobile task

Infants born very preterm (PT), prior to 32 weeks gestation, are at increased risk of developing cerebral palsy. Children with spastic cerebral palsy have impaired selective leg joint movement, which contributes to lifelong walking limitations. We investigated whether infants born PT generated more selective hip-knee joint movement (e.g., hip flexes as knee extends) while participating in a scaffolded mobile task. Infants born PT and infants born full-term (FT) at 4 months corrected age participated in a scaffolded mobile task for 2-3 consecutive days. The scaffolded mobile task required infants to raise their legs vertically over a virtual threshold. Three threshold heights (low, middle, and high) were used to test whether the middle and high heights encourage infants to move their legs more selectively. Fifteen infants born FT learned the task and showed more selective hip-knee movement at each of the three threshold heights on the day that they learned, compared with their baseline spontaneous kicking. Thirteen infants born PT learned the task and showed more selective hip-knee movement on their learning day, but only when the middle and high thresholds were used. The results show that the scaffolded mobile task effectively encouraged infants to generate more selective hip-knee joint movement.

Infants born full term and preterm increase the height of anti-gravity leg movements during a kick-activated mobile task using a scaffolded task environment

Prior research supports that infants born very preterm (PT), compared with full term (FT), have early differences in rate of learning and motor control that may hinder their ability to learn challenging motor tasks. Four-month-old infants born FT (n = 18) and PT (n = 18) participated in an infant kick-activated mobile task that was scaffolded to motivate progressively higher kicks. We found the FT group learned the association between their leg movements and mobile activation on the second day, but the PT group learned the association on the third day. Both groups of infants increased the height of their kicks on the day they learned the task, compared with their spontaneous kicking height. These findings suggest that infants born PT have the ability to learn challenging motor tasks, such as kicking high, when participating in a task environment that uses scaffolding.

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.

A Motor Learning Paradigm Combining Technology and Associative Learning to Assess Prone Motor Learning in Infants

BACKGROUND

Associative learning is the ability to discover a relationship between two or more events. We combined principles of learning and technology to develop a paradigm to assess associative learning in prone.

PURPOSE

The purpose of this study was to determine whether 3- to 6-month-old infants can demonstrate: (1) short-term learning of an association between their upper body movements in prone and activation of a toy, and (2) retention of the association learned on day 1, 24 hours later.

METHODS

Twenty-eight infants who were 3 to 6 months of age and who were typically developing were tested for 2 consecutive days in an instrumented play gym. Both days of testing had a baseline and 4 acquisition phases (2 minutes each). During the acquisition phase, the toy activated for a maximum of 10 seconds when the infant's head was above a threshold. A criterion was set a priori to distinguish infants as short-term learners and retainers of the association learned on day 1.

RESULTS

Of 28 infants, 22 and 14 infants completed all phases of the testing on day 1 and day 2, respectively. Fourteen (50%) of the infants met the criteria for short-term learners. On day 2, there was an analyzable sample of 9 short-term learners. Three of the 12 short-term learners (25%) demonstrated retention on day 2.

CONCLUSION

Consistent with prior infant motor learning research, half of the infants demonstrated associative learning in this novel assessment in prone; however, based on study criteria, the infants had limited retention of the association on day 2.

Neonatal Skin-to-Skin Contact: Implications for Learning and Autonomic Nervous System Function in Infants With Congenital Heart Disease

Background:

Infants with complex congenital heart disease (CCHD) often develop neurodevelopmental disabilities. Cognitive abilities are associated with vagally mediated autonomic function. Skin-to-skin contact (SSC) interventions enhance infant neurodevelopment and autonomic function in other high-risk populations.

Aim:

To examine the effects of a neonatal SSC intervention on learning and autonomic function in 3-month-old infants: infants with CCHD who received neonatal SSC ( n = 10), typically developing (TD) infants ( n = 16), and infants with CCHD without SSC ( n = 10).

Methods:

This secondary data analysis measured cognitive function using the mobile paradigm (MP), a classic measure of learning based on operant conditioning. Autonomic function was assessed with heart rate (HR) and HR variability (HRV). Data were analyzed with repeated-measures general linear mixed modeling with α = .10 for this exploratory study.

Results:

Learning rates were TD = 75%, cardiac-SSC = 70%, and cardiac-control = 40%. Learners demonstrated significant reductions in HRV during the MP; nonlearners exhibited no change. TD and cardiac-SSC groups exhibited increases in HR and reductions in HRV during the MP. No significant changes occurred in the cardiac-control group. Nonlinear HRV during the MP differed only in the TD group.

Conclusions:

Findings suggest improvements in cognitive and autonomic development in 3-month-old infants with CCHD who received neonatal SSC. Learning and autonomic function results in infants with CCHD who had not received SSC suggest reduced capacity to muster the physiologic resources to carry out this cognitive task. Findings provide preliminary evidence in support of implementation of SSC with infants with CCHD and support additional research.

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.

The influence of prenatal experience on behavioral and social development: The benefits and limitations of an animal model

Prenatal experience is both a formative and a regulatory force in the process of development. As a result, birth is not an adequate starting point for explanations of behavioral development. However, surprisingly little is currently known regarding the role of prenatal experience in the emergence and facilitation of perceptual, cognitive, or social development. Our lack of knowledge in this area is due in part to the very restricted experimental manipulations possible with human fetuses. A comparative approach utilizing animal models provides an essential step in addressing this gap in our knowledge and providing testable predictions for studies with human fetuses, infants, and children. Further, animal-based comparative research serves to minimize the amount of exploratory research undertaken with human subjects and hone in on issues and research directions worthy of further research investment. In this article, I review selected animal-based research exploring how developmental influences during the prenatal period can guide and constrain subsequent behavioral and social development. I then discuss the importance of linking the prenatal environment to postnatal outcomes in terms of how psychologists conceptualize “innate” biases, preferences, and skills in the study of human development.

Prenatal maternal cortisol measures predict learning and short-term memory performance in 3- but not 5-month-old infants

Little is known about relations between maternal prenatal stress and specific cognitive processes-learning and memory-in infants. A modified crib-mobile task was employed in a longitudinal design to test relations between maternal prenatal cortisol, prenatal subjective stress and anxiety, psychosocial variables, and learning and memory in 3- and 5-month-old infants. Results revealed that maternal prenatal cortisol was affected by particular psychosocial variables (e.g., maternal age, whether or not the infant's grandmother provided childcare, financial status), but was unrelated to measures of maternal depression, anxiety, and stress. Although maternal prenatal cortisol was not predictive of learning or memory performance in 5-month-old infants, higher levels of basal maternal cortisol and reduced prenatal cortisol response was predictive of some learning and short-term memory measures in 3-month-old infants. These results suggest an influence of maternal neuroendocrine functioning on fetal neurological development, and the importance of separate examination of subjective and biological measures of stress.

The mobile conjugate reinforcement paradigm in a lab setting

The mobile conjugate reinforcement task was administered to 4-month-old infants in a lab rather than a home setting where it is usually administered. Learning and retention patterns were comparable to those of infants tested in their homes, suggesting flexibility in where this task can be administered. These results pave the way for this task to be used with a broader range of infants for whom home visits are not practical or convenient (e.g., infants in child care). Developmental research conducted with a more diverse population of infants would facilitate our understanding of cognitive development very early in life.

Vagal tone during infant contingency learning and its disruption

This study used contingency learning to examine changes in infants' vagal tone during learning and its disruption. The heart rate of 160 five-month-old infants was recorded continuously during the first of two training sessions as they experienced an audiovisual event contingent on their pulling. Maternal reports of infant temperament were also collected. Baseline vagal tone, a measure of parasympathetic regulation of the heart, was related to vagal levels during the infants' contingency learning session, but not to their learner status. Vagal tone levels did not vary significantly over session minutes. Instead, vagal tone levels were a function of both individual differences in learner status and infant soothability. Vagal levels of infants who learned in the initial session were similar regardless of their soothability; however, vagal levels of infants who learned in a subsequent session differed as a function of soothability. Additionally, vagal levels during contingency disruption were significantly higher among infants in this group who were more soothable as opposed to those who were less soothable. The results suggest that contingency learning and disruption is associated with stable vagal tone in the majority of infants, but that individual differences in attention processes and state associated with vagal tone may be most readily observed during the disruption phase.

Sensory processing disorder in children ages birth-3 years born prematurely: a systematic review

This systematic review of multidisciplinary literature synthesizes evidence of the prevalence and patterns of sensory processing disorder (SPD) in children ages birth-3 yr born preterm. Forty-five articles including physiological, behavioral, temperament, and SPD research met the inclusion criteria and provided 295 findings related to SPD-130 (44%) positive (evidence of SPD) and 165 (56%) negative (no evidence of SPD). The majority of findings related to sensory modulation disorder (SMD; 43% positive). The most prevalent subcategory of SMD was sensory overresponsivity (82% of findings positive). Evidence of sensory underresponsivity and sensory-seeking SMD, sensory discrimination disorder, and sensory-based motor disorder was limited. This study supports the education of neonatologists, pediatricians, and caregivers about the symptoms and potential consequences of SPD and helps justify the need for follow-up screening for SPD in children ages birth-3 yr born preterm. Research using measures based on sensory processing theory is needed.

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

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

Behavior During Tethered Kicking in Infants With Periventricular Brain Injury

PURPOSE

To describe behavior of children with periventricular brain injury (PBI) in a tethered-kicking intervention.

METHODS

Sixteen infants with PBI were randomly assigned to exercise or no-training in a longitudinal pilot study. Frequencies of leg movements and interlimb coordination were described from videos at 2 and 4 months' corrected age (CA).

RESULTS

Eight of the 13 children (62%) with longitudinal data increased the frequency of leg movements while tethered to a mobile between 2 and 4 months' CA. Movement frequency was correlated with scores on the Test of Infant Motor Performance, but no differences between experimental groups were found. Children with typical development at 12 months' CA increased the proportion of leg movements that were synchronous between 2 and 4 months, as did a child with cerebral palsy in the experimental group.

CONCLUSIONS

The tethered-kicking intervention facilitates movement in infants with PBI, but effects on development remain to be demonstrated.

Assessment and stability of early learning abilities in preterm and full-term infants across the first two years of life

Infants born preterm have increased risk for learning disabilities yet we lack assessments to successfully detect these disabilities in early life. We followed 23 full-term and 29 preterm infants from birth through 24 months to assess for differences in and stability of learning abilities across time. Measures included the Bayley-III cognitive subscale, the mobile paradigm assessment, and a means-end learning assessment. Preterm infants had poorer performance on measures of cognition and learning across the first two years of life. Learning performance at 3-4 months was consistent with learning performance at 12-24 months of age. At 3-4 months, the mobile paradigm had better sensitivity and predictive values for predicting 24-month cognitive delays on the Bayley-III than did the Bayley-III itself. At 12-18 months, the means-end learning assessment had better sensitivity than the Bayley-III for identifying 24-month cognitive delays on the Bayley-III. The results suggest that: (1) infants born preterm may demonstrate learning differences as early as the first few months of life, (2) learning differences identified in the first months of life are likely to persist throughout the second year of life, and (3) learning assessments that measure how infants and toddlers use their typical behaviors to problem-solve to control external events may be more effective than traditional standardized assessment tools for detecting early learning delays.

Motor contingency learning and infants with Spina Bifida

Infants with Spina Bifida (SB) were compared to typically developing infants (TD) using a conjugate reinforcement paradigm at 6 months-of-age (n = 98) to evaluate learning, and retention of a sensory-motor contingency. Analyses evaluated infant arm-waving rates at baseline (wrist not tethered to mobile), during acquisition of the sensory-motor contingency (wrist tethered), and immediately after the acquisition phase and then after a delay (wrist not tethered), controlling for arm reaching ability, gestational age, and socioeconomic status. Although both groups responded to the contingency with increased arm-waving from baseline to acquisition, 15% to 29% fewer infants with SB than TD were found to learn the contingency depending on the criterion used to determine contingency learning. In addition, infants with SB who had learned the contingency had more difficulty retaining the contingency over time when sensory feedback was absent. The findings suggest that infants with SB do not learn motor contingencies as easily or at the same rate as TD infants, and are more likely to decrease motor responses when sensory feedback is absent. Results are discussed with reference to research on contingency learning in infants with and without neurodevelopmental disorders, and with reference to motor learning in school-age children with SB.

Does neonatal morphine use affect neuropsychological outcomes at 8 to 9 years of age?

Morphine is widely used to treat severe pain in neonatal intensive care unit patients. Animal studies suggest adverse long-term side effects of neonatal morphine, but a follow-up study of 5-year-old children who participated in a morphine-placebo controlled trial as newborns found no such effects on the child's general functioning. This study indicated that morphine may negatively affect response inhibition, a domain of executive functions. Therefore, we performed a second follow-up study in the same population at the age of 8 to 9 years, focused on the child's general functioning in terms of intelligence, visual motor integration, and behavior and on executive functions. Children in the morphine group showed significantly less externalizing problems according to the parents but more internalizing behavior according to the teachers, but only after adjustment for intelligence quotient (IQ), potential confounders using a propensity score, and additional open-label morphine. Morphine-treated children showed significantly fewer problems with executive functions in daily life as rated by parents for the subscales inhibition and organization of materials and for planning/organizing as rated by the teachers. After adjustment for IQ and the propensity score, executive functioning as rated by the parents remained statistically significantly better in the morphine-treated group. The influence of the additional morphine given was not of a significant influence for any of the outcome variables. Overall, the present study demonstrates that continuous morphine infusion of 10 μg/kg/h during the neonatal period does not harm general functioning and may even have a positive influence on executive functions at 8 to 9 years.

Cycled light exposure reduces fussing and crying in very preterm infants

OBJECTIVE

To examine whether cycled lighting (CL) conditions during neonatal care in very preterm infants (<32 weeks' gestational age [GA]) decrease crying and fussing behavior, improve the consolidation of sleep, and influence activity behavior at 5 and 11 weeks' postterm corrected age (CA) compared with preterm infants cared for in dim lighting (DL) conditions.

METHODS

Thirty-seven preterm infants were randomly assigned to CL (7 am-7 pm lights on, 7 pm-7 am lights off [n = 17; mean GA: 30.6 ± 0.95 weeks; 9 girls]) or DL (lights off whenever the child is asleep [n = 20; GA: 29.5 ± 2.1 weeks; 8 girls]) conditions. Sleeping, crying, and activity behavior was recorded by using parental diaries and actigraphy at 5 and 11 weeks' CA.

RESULTS

A significant reduction of fussing (59.4 minutes/24 hours [± 25.8 minutes]) and crying (31.2 minutes/24 hours [± 14.4 minutes]) behavior and a trend to higher motor activity during daytime was found in CL-exposed infants at 5 and 11 weeks' CA compared with infants cared for in DL conditions. No significant difference between groups was observed for sleep behavior at 5 and 11 weeks' CA. Infants in CL conditions showed a trend to improved daily weight gain (average: 3.6 g/d) during neonatal care compared with DL conditions.

CONCLUSIONS

CL conditions in neonatal care have beneficial effects on infant's fussing and crying behavior and growth in the first weeks of life. This study supports the introduction of CL care in clinical neonatal practice.

Differential associations between sensory response patterns and language, social, and communication measures in children with autism or other developmental disabilities

PURPOSE

To examine patterns of sensory responsiveness (i.e., hyperresponsiveness, hyporesponsiveness, and sensory seeking) as factors that may account for variability in social-communicative symptoms of autism and variability in language, social, and communication skill development in children with autism or other developmental disabilities (DDs).

METHOD

Children with autistic disorder (AD; n = 72, mean age = 52.3 months) and other DDs (n = 44, mean age = 48.1 months) participated in a protocol measuring sensory response patterns; social-communicative symptoms of autism; and language, social, and communication skills.

RESULTS

Hyporesponsiveness was positively associated with social-communicative symptom severity, with no significant group difference in the association. Hyperresponsiveness was not significantly associated with social-communicative symptom severity. A group difference emerged for sensory seeking and social-communicative symptom severity, with a positive association for the AD group only. For the 2 groups of children combined, hyporesponsiveness was negatively associated with language skills and social adaptive skills. Sensory seeking also was negatively associated with language skills. These associations did not differ between the 2 groups.

CONCLUSIONS

Aberrant sensory processing may play an important role in the pathogenesis of autism and other DDs as well as in the rate of acquisition of language, social, and communication skills.

Physiological correlates of memory recall in infancy: vagal tone, cortisol, and imitation in preterm and full-term infants at 6 months

We examined the role of physiological regulation (heart rate, vagal tone, and salivary cortisol) in short-term memory in preterm and full-term 6-month-old infants. Using a deferred imitation task to evaluate social learning and memory recall, an experimenter modeled three novel behaviors (removing, shaking, and replacing a glove) on a puppet. Infants were tested immediately after being shown the behaviors as well as following a 10-min delay. We found that greater suppression of vagal tone was related to better memory recall in full-term infants tested immediately after the demonstration as well as in preterm infants tested later after a 10-min delay. We also found that preterm infants showed greater coordination of physiology (i.e., tighter coupling of vagal tone, heart rate, and cortisol) at rest and during retrieval than full-term infants. These findings provide new evidence of the important links between changes in autonomic activity and memory recall in infancy. They also raise the intriguing possibility that social learning, imitation behavior, and the formation of new memories are modulated by autonomic activity that is coordinated differently in preterm and full-term infants.

Neonatal pain, parenting stress and interaction, in relation to cognitive and motor development at 8 and 18 months in preterm infants

Procedural pain in the neonatal intensive care unit triggers a cascade of physiological, behavioral and hormonal disruptions which may contribute to altered neurodevelopment in infants born very preterm, who undergo prolonged hospitalization at a time of physiological immaturity and rapid brain development. The aim of this study was to examine relationships between cumulative procedural pain (number of skin-breaking procedures from birth to term, adjusted for early illness severity and overall intravenous morphine exposure), and later cognitive, motor abilities and behavior in very preterm infants at 8 and 18 months corrected chronological age (CCA), and further, to evaluate the extent to which parenting factors modulate these relationships over time. Participants were N=211 infants (n=137 born preterm 32 weeks gestational age [GA] and n=74 full-term controls) followed prospectively since birth. Infants with significant neonatal brain injury (periventricular leucomalacia, grade 3 or 4 intraventricular hemorrhage) and/or major sensori-neural impairments, were excluded. Poorer cognition and motor function were associated with higher number of skin-breaking procedures, independent of early illness severity, overall intravenous morphine, and exposure to postnatal steroids. The number of skin-breaking procedures as a marker of neonatal pain was closely related to days on mechanical ventilation. In general, greater overall exposure to intravenous morphine was associated with poorer motor development at 8 months, but not at 18 months CCA, however, specific protocols for morphine administration were not evaluated. Lower parenting stress modulated effects of neonatal pain, only on cognitive outcome at 18 months.