Is the late preterm infant more vulnerable to gray matter injury than the term infant?

Grade 7 school performance of children born preterm: a retrospective Canadian Cohort study

IMPORTANCE

Data on the middle school outcomes of preterm children are limited and have methodologic issues.

OBJECTIVE

To study the association between preterm birth and grade 7 school performance.

METHODS

A retrospective population-based cohort study of children born in Manitoba, Canada between 1994 and 2006 using their grade 7 school performance data. A secondary sibling cohort was created comprising children born preterm and their full-term siblings. Primary exposure was preterm birth categorized as <28, 28-33 and 34-36 weeks gestation. The two co-primary grade 7 outcome measures were: not meeting the mathematics competencies, and not meeting the student engagement competencies. Multivariable logistic regression models tested the association between preterm birth and both co-primary outcomes; adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated.

RESULTS

7653 preterm (gestational age median [IQR]: 35 weeks [34,36]) and 110,313 term (40 [39,40]) were included. 43% of < 28 weeks, 18% of 28-33 weeks and 17% of 34-36 weeks had the mathematics co-primary outcome compared to 13% of term children. The corresponding % for the student engagement outcome were 42%, 24%, 24% and 24% respectively. Preterm birth was associated with the mathematics (<28 weeks: 5.48, 3.89-7.70; 28-33 weeks: 1.47, 1.27-1.70; 34-36 weeks: 1.26, 1.16-1.35) and student engagement outcomes (<28 weeks: 2.49, 1.76-3.51; 28-33 weeks: 1.21, 1.06-1.39; 34-36 weeks: 1.09, 1.01-1.16). However, there was no difference in outcomes among the sibling cohort.

CONCLUSIONS AND RELEVANCE

Children born preterm had lower grade 7 performance compared to children born term in this population-based cohort. Screening and supports for them in their middle school years are warranted.

Creatine in the fetal brain: A regional investigation of acute global hypoxia and creatine supplementation in a translational fetal sheep model

Background

Creatine supplementation during pregnancy is a promising prophylactic treatment for perinatal hypoxic brain injury. Previously, in near-term sheep we have shown that fetal creatine supplementation reduces cerebral metabolic and oxidative stress induced by acute global hypoxia. This study investigated the effects of acute hypoxia with or without fetal creatine supplementation on neuropathology in multiple brain regions.

Methods

Near-term fetal sheep were administered continuous intravenous infusion of either creatine (6 mg kg^-1 h^-1) or isovolumetric saline from 122 to 134 days gestational age (dGA; term is approx. 145 dGA). At 131 dGA, global hypoxia was induced by a 10 min umbilical cord occlusion (UCO). Fetuses were then recovered for 72 h at which time (134 dGA) cerebral tissue was collected for either RT-qPCR or immunohistochemistry analyses.

Results

UCO resulted in mild injury to the cortical gray matter, thalamus and hippocampus, with increased cell death and astrogliosis and downregulation of genes involved in regulating injury responses, vasculature development and mitochondrial integrity. Creatine supplementation reduced astrogliosis within the corpus callosum but did not ameliorate any other gene expression or histopathological changes induced by hypoxia. Of importance, effects of creatine supplementation on gene expression irrespective of hypoxia, including increased expression of anti-apoptotic (BCL-2) and pro-inflammatory (e.g., MPO, TNFa, IL-6, IL-1β) genes, particularly in the gray matter, hippocampus, and striatum were identified. Creatine treatment also effected oligodendrocyte maturation and myelination in white matter regions.

Conclusion

While supplementation did not rescue mild neuropathology caused by UCO, creatine did result in gene expression changes that may influence in utero cerebral development.

Behavioral and neuroanatomical outcomes following altered serotonin expression in a hypoxic-ischemic injury neonate rodent model

BACKGROUND

Children born prematurely (<37 gestational weeks) are at risk for a variety of adverse medical events. They may experience ischemic and/or hemorrhagic events leading to negative neural sequelae. They are also exposed to repeated stressful experiences as part of life-saving care within the neonatal intensive care unit (NICU). These experiences have been associated with methylation of SLC6A4, a gene which codes for serotonin transport proteins, and is associated with anxiety, depression, and increased incidence of autism spectrum disorders.The purpose of this study was to examine the effects of altered serotonin levels on behavioral and neuroanatomical outcomes in a neonatal rodent model with or without exposure to hypoxic-ischemic (HI) injury.

METHODS

Wistar rat pups were randomly assigned to either HI injury or sham groups. Pups within each group were treated with a chronic SSRI (Citalopram HBr) to simulate the effects of SLC6A4 methylation, or saline (NS). Subjects were assessed on behavioral tasks and neuropathologic indices.

RESULTS

HI injured subjects performed poorly on behavioral tasks. SSRI subjects did not display significantly greater anxiety. HI + SSRI subjects learned faster than HI+NS. Histologically, SSRI subjects had predominantly larger brain volumes than NS.

CONCLUSION

SSRI treated subjects without injury showed patterns of increased anxiety, consistent with theories of SLC6A4 methylation. The paradoxical trend to improved cognition in HI+SSRI subjects relative to HI alone, may reflect an unexpected SSRI neuroprotective effect in the presence of injury, and may be related to serotonin-induced neurogenesis.

Effects of Intrauterine Inflammation on Cortical Gray Matter of Near-Term Lambs

Introduction: Ventilation causes cerebral white matter inflammation and injury, which is exacerbated by intrauterine inflammation. However, the effects on cortical gray matter are not well-known. Our aim was to examine the effect of ventilation on the cerebral cortex of near-term lambs exposed to intrauterine inflammation. Method:Pregnant ewes at 119 ± 1 days gestation received an intra-amniotic injection of saline or lipopolysaccharide (LPS; 10 mg). Seven days later, lambs were randomized to either a high tidal volume injurious ventilation strategy (INJ_SALN = 6, INJ_LPSN = 5) or a protective ventilation strategy (PROT_SALN = 5, PROT_LPSN = 6). Respiratory parameters, heart rate and blood gases were monitored during the neonatal period. At post-mortem, the brain was collected and processed for immunohistochemical assessment. Neuronal density (NeuN), apoptotic cell death (caspase 8 and TUNEL), microglial density (Iba-1), astrocytic density (GFAP), and vascular protein extravasation (sheep serum) were assessed within the frontal, parietal, temporal and occipital lobes of the cerebral cortex. Results:A significant reduction in the number of neurons in all cortical layers except 4 was observed in LPS-exposed lambs compared to controls (layer #1: p = 0.041; layers #2 + 3: p = 0.023; layers #5 + 6: p = 0.016). LPS treatment caused a significant increase in gray matter area, indicative of edema. LPS+ventilation did not cause apoptotic cell death in the gray matter. Astrogliosis was not observed following PROT or INJ ventilation, with or without LPS exposure. LPS exposure was associated with vascular protein extravasation. Conclusion:Ventilation had little effect on gray matter inflammation and injury. Intrauterine inflammation reduced neuronal cell density, caused edema of the cortical gray matter, and blood vessel extravasation in the brain of near-term lambs.

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

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

CONCLUSION

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

Late preterm infants' motor development until term age

OBJECTIVES:

To analyze the motor development of late preterm newborn infants (LPI) from birth to term-corrected age using the Test of Infant Motor Performance (TIMP) and to compare the obtained results with those of term infants at birth.

METHODS:

Prospective cohort study, 29 late preterm newborn infants were evaluated by the TIMP at birth and every two weeks until term-corrected age. The TIMP was administered to 88 term infants at birth.

RESULTS:

The mean TIMP score of late preterm newborn infants was 51.9±5.8 at 34-35 weeks and 62.6±5.2 at 40 weeks. There was a significant increase at 38-39 weeks in the LPI group (p<0.05). There were no significant differences in the motor evaluations between term infants at birth and LPI at the equivalent age.

CONCLUSION:

The LPI presented a gradual progression of motor development until the term-corrected age, but differences with term infants at birth were not detected.

Gestational Age and Kindergarten School Readiness in a National Sample of Preterm Infants

OBJECTIVE

To examine the association of gestational age with school readiness in kindergarten reading and math skills. We hypothesized that compared with infants born at 39-41 weeks, infants born at lower gestational ages would have poorer school readiness.

STUDY DESIGN

The study sample comprised 5250 children from the Early Childhood Longitudinal Study, Birth Cohort, assessed with specialized reading and math assessments at kindergarten. Poor school readiness was characterized by reading and math theta scores ≥1.5 SD below the sample mean. The aOR and 95% CI of poor school readiness were estimated using multivariate logistic regression, examining gestational age continuously and categorically (very preterm [VPT], moderate/late preterm [M/LPT], early term [ET], and term). Pairwise comparisons were performed to test for differences by gestational age category.

RESULTS

There was an association between gestational age and poor school readiness for reading and math, with the suggestion of a threshold effect in children born at ≥32 weeks gestation. In adjusted models, in VPT infants, the aORs of poor school readiness in reading and math were 2.58 (95% CI, 1.29-5.15) and 3.38 (95% CI, 1.66-6.91), respectively. For infants born M/LPT and ET, the odds of poor school readiness in reading did not differ from those of children born full-term, however.

CONCLUSIONS

Compared with term infants, the highest odds of poor school readiness in reading and math were seen in VPT infants, with lower odds of poor school readiness in children born at ≥32 weeks gestation. Ongoing developmental surveillance before kindergarten is indicated for VPT infants.

Sex differences in behavioral outcomes following temperature modulation during induced neonatal hypoxic ischemic injury in rats

Neonatal hypoxia ischemia (HI; reduced oxygen and/or blood flow to the brain) can cause various degrees of tissue damage, as well as subsequent cognitive/behavioral deficits such as motor, learning/memory, and auditory impairments. These outcomes frequently result from cardiovascular and/or respiratory events observed in premature infants. Data suggests that there is a sex difference in HI outcome, with males being more adversely affected relative to comparably injured females. Brain/body temperature may play a role in modulating the severity of an HI insult, with hypothermia during an insult yielding more favorable anatomical and behavioral outcomes. The current study utilized a postnatal day (P) 7 rodent model of HI injury to assess the effect of temperature modulation during injury in each sex. We hypothesized that female P7 rats would benefit more from lowered body temperatures as compared to male P7 rats. We assessed all subjects on rota-rod, auditory discrimination, and spatial/non-spatial maze tasks. Our results revealed a significant benefit of temperature reduction in HI females as measured by most of the employed behavioral tasks. However, HI males benefitted from temperature reduction as measured on auditory and non-spatial tasks. Our data suggest that temperature reduction protects both sexes from the deleterious effects of HI injury, but task and sex specific patterns of relative efficacy are seen.

Mild maturational delay of the brainstem at term in late preterm small-for-gestation age babies

AIMS

To detect any functional abnormality in the brainstem auditory pathway in late preterm babies born of small-for-gestational age (SGA) using maximum length sequence brainstem evoked response.

STUDY DESIGN

The response was recorded and analyzed at term in 38 SGA (birthweight <3rd centile) babies born at 33-36 week gestation. The results were compared with 40 age-matched babies born of appropriate-for-gestational age (AGA) (birthweight >10th centile). None of the subjects had major perinatal problems.

RESULTS

All wave latencies and interpeak intervals in the SGA group were slightly longer than those in the AGA group at most click rates. Wave III latency was significantly longer than that in the AGA group at 227/s (P < 0.05), and wave V latency was at 227 and 910/s (P < 0.05 and 0.05). Of the interpeak intervals, only the I-V interval in the SGA group was significantly longer than that in the AGA group at the highest rate 910/s (P < 0.05). The amplitudes of waves I, III and V in the SGA group all tended to be smaller than those in the AGA group at all click rates 91-910/s. The wave V amplitude was significantly smaller at most click rates (227-910/s, all P < 0.05). The slopes of all wave latency-, interval-, and amplitude-rate functions were similar in SGA and AGA groups.

CONCLUSIONS

There were marginal abnormalities in MLS BAER of low-risk late preterm SGA babies, suggesting a mild degree of maturational delay in the brainstem. Intrauterine growth retardation occurring in late preterm babies has a minor effect on neural maturation of the immature brainstem.

Dissociation in the Effects of Induced Neonatal Hypoxia-Ischemia on Rapid Auditory Processing and Spatial Working Memory in Male Rats

Infants born prematurely are at risk for cardiovascular events causing hypoxia-ischemia (HI; reduced blood and oxygen to the brain). HI in turn can cause neuropathology, though patterns of damage are sometimes diffuse and often highly variable (with clinical heterogeneity further magnified by rapid development). As a result, though HI injury is associated with long-term behavioral and cognitive impairments in general, pathology indices for specific infants can provide only limited insight into individual prognosis. The current paper addresses this important clinical issue using a rat model that simulates unilateral HI in a late preterm infant coupled with long-term behavioral evaluation in two processing domains - auditory discrimination and spatial learning/memory. We examined the following: (1) whether deficits on one task would predict deficits on the other (suggesting that subjects with more severe injury perform worse across all cognitive domains) or (2) whether domain-specific outcomes among HI-injured subjects would be uncorrelated (suggesting differential damage to orthogonal neural systems). All animals (sham and HI) received initial auditory testing and were assigned to additional auditory testing (group A) or spatial maze testing (group B). This allowed within-task (group A) and between-task (group B) correlation. Anatomic measures of cortical, hippocampal and ventricular volume (indexing HI damage) were also obtained and correlated against behavioral measures. Results showed that auditory discrimination in the juvenile period was not correlated with spatial working memory in adulthood (group B) in either sham or HI rats. Conversely, early auditory processing performance for group A HI animals significantly predicted auditory deficits in adulthood (p = 0.05; no correlation in shams). Anatomic data also revealed significant relationships between the volumes of different brain areas within both HI and shams, but anatomic measures did not correlate with any behavioral measure in the HI group (though we saw a hippocampal/spatial correlation in shams, in the expected direction). Overall, current data provide an impetus to enhance tools for characterizing individual HI-related pathology in neonates, which could provide more accurate individual prognoses within specific cognitive/behavioral domains and thus improved patient-specific early interventions.

[Recommendations for the perinatal management and follow up of late preterm newborns]

Prematurity is the main reason for neonatal morbidity and mortality, and has become one of the greatest problems in public health, especially in developed countries. Prematurity rate has increased during the last 2 decades. This increase may be attributed to late preterm babies, that is, those with a gestational age between 34(+0) and 36(+6) weeks. Perinatal morbidities, as well as long term complications, are more frequent in this population than in term babies. The incidence is more similar to the one observed in earlier premature babies. The SEN34-36 group of the Spanish Society of Neonatology suggests these recommendations for the management of late preterm babies. Strategies are offered not only for the early detection of possible complications, but also for the correction of these morbidities, and from the point of view of a family and development centered care. Follow up is strongly recommended due to the high rate of late morbidities.

Management of breastfeeding during and after the maternity hospitalization for late preterm infants

Among infants born moderately and late preterm or early term, the greatest challenge for breastfeeding management is the late preterm infant (LPI) who is cared for with the mother in the maternity setting. Breastfeeding failure among LPIs and their mothers is high. Evidence-based strategies are needed to protect infant hydration and growth, and the maternal milk supply, until complete feeding at breast can be established. This article reviews the evidence for lactation and breastfeeding risks in LPIs and their mothers, and describes strategies for managing these immaturity-related feeding problems. Application to moderately and early preterm infants is made throughout.

Neuropathologic studies of the encephalopathy of prematurity in the late preterm infant

It has been widely suggested that brain damage in survivors of late preterm deliveries is similar to that in early preterm infants, only less severe. This report addresses this concept through reanalysis of published neuropathologic data obtained according to late preterm in comparison with early preterm ages. Findings suggest that the spectrum of brain injury in the late preterm infant, as determined in an autopsy population, is similar to that found in early preterm infants, with potential differential susceptibility for different neuronal, glial, and vascular indices. Further research is needed to more clearly define developmental cellular susceptibilities in preterm populations.

Neural conduction abnormality in the brain stem and prevalence of the abnormality in late preterm infants with perinatal problems

Neurodevelopment in late preterm infants has recently attracted considerable interest. The prevalence of brain stem conduction abnormality remains unknown. We examined maximum length sequence brain stem auditory evoked response in 163 infants, born at 33-36 weeks gestation, who had various perinatal problems. Compared with 49 normal term infants without problems, the late preterm infants showed a significant increase in III-V and I-V interpeak intervals at all 91-910/s clicks, particularly at 455 and 910/s (p < 0.01-0.001). The I-III interval was slightly increased, without statistically significant difference from the controls at any click rates. These results suggest that neural conduction along the, mainly more central or rostral part of, auditory brain stem is abnormal in late preterm infants with perinatal problems. Of the 163 late preterm infant, the number (and percentage rate) of infants with abnormal I-V interval at 91, 227, 455, and 910/s clicks was, respectively, 11 (6.5%), 17 (10.2%), 37 (22.3%), and 31 (18.7%). The number (and percentage rate) of infants with abnormal III-V interval at these rates was, respectively, 10 (6.0%), 17 (10.2%), 28 (16.9), and 36 (21.2%). Apparently, the abnormal rates were much higher at 455 and 910/s clicks than at lower rates 91 and 227/s. In total, 42 (25.8%) infants showed abnormal I-V and/or III-V intervals.

CONCLUSION

Conduction in, mainly in the more central part, the brain stem is abnormal in late preterm infants with perinatal problems. The abnormality is more detectable at high- than at low-rate sensory stimulation. A quarter of late preterm infants with perinatal problems have brain stem conduction abnormality.

Functioning of 7-year-old children born at 32 to 35 weeks' gestational age

OBJECTIVE

To compare neuropsychological functions in moderately preterm (32-35 weeks' gestation) and full-term children at the age of 7 years and identify gender differences.

METHODS

Community-based prospective cohort study of 248 moderately preterm children (138 boys) and 130 full-term children (58 boys). Neuropsychological tests included IQ, memory, attention, visual perception, motor skills, visuomotor skills, and parental report of executive functioning.

RESULTS

The moderately preterm group performed significantly worse on total and performance IQ, visuospatial reasoning, attention control, inhibition, and executive functioning. No differences were found in verbal IQ, verbal memory, and visuomotor and motor skills. Preterm children were at higher risk for scores <10th percentile on intelligence, visuospatial reasoning (relative risk ratio both: 1.69 [95% confidence interval: 1.29-2.28]), and executive functioning problems (relative risk: 1.94 [95% confidence interval: 1.51-2.57]). Using gender-specific norms, preterm boys performed significantly worse than full-term boys on visuospatial reasoning (P < .01); preterm girls performed significantly worse than full-term girls on visuospatial reasoning, intelligence, attention, and executive functioning (P < .05).

CONCLUSIONS

Moderately preterm birth is associated with lower intelligence and poorer neuropsychological functioning at early school age. No differences in motor skills and verbal memory were found. Using gender-specific norms, our data suggest that moderately preterm boys catch up, whereas moderately preterm girls lag behind their peers on various neuropsychological functions by the age of 7 years.

Glucocorticoids and preterm hypoxic-ischemic brain injury: the good and the bad

Fetuses at risk of premature delivery are now routinely exposed to maternal treatment with synthetic glucocorticoids. In randomized clinical trials, these substantially reduce acute neonatal systemic morbidity, and mortality, after premature birth and reduce intraventricular hemorrhage. However, the overall neurodevelopmental impact is surprisingly unclear; worryingly, postnatal glucocorticoids are consistently associated with impaired brain development. We review the clinical and experimental evidence on how glucocorticoids may affect the developing brain and highlight the need for systematic research.

Nitric oxide and antioxidant enzymes in venous and cord blood of late preterm and term omani mothers

OBJECTIVES

This study assessed the role of oxidative stress in parturition in Omani mothers following growing reports that late preterm neonates were at greater risk than term neonates of perinatal death.

METHODS

Venous blood samples were collected during labour, and cord (neonatal) blood samples were taken after childbirth in late preterm and term from women at Sultan Qaboos University Hospital, Oman. Plasma nitric oxide (NO) concentrations, erythrocyte catalase (CAT). Erythrocyte glutathione peroxidase (GPx) activities were measured using spectrophotometric methods.

RESULTS

When compared with term mothers, late preterm mothers had markedly higher NO concentrations (μmol/L) 17.1 ± 3.3 versus 11.0 ± 5.5 (P <0.0001), and lower GPx values (U/g Hb) 94.1 ± 12.9 versus 110.4 ± 12.3 (P <0.0001). Late preterm mothers were significantly younger (P = 0.027) than term mothers and had neonates that weighed significantly less (P <0.0001) than term neonates. GPx activity was significantly reduced (P = 0.001) in late preterm neonates as compared to term neonates. CAT showed no change in activity in any comparison.

CONCLUSION

Distinctly higher values of NO and lower GPx activity were found in late preterm mothers relative to term mothers; also, lower GPx in late preterm neonates relative to term neonates suggested a pro-oxidant-antioxidant imbalance due to the greater oxidative burden in late preterm parturition.

The relationship of brain development and breastfeeding in the late-preterm infant

Late-preterm infants (34 0/7-36 6/7 weeks gestation) are physiologically and developmentally immature at birth. The relationship between brain development and feeding is important since adequate oral intake is imperative to prevent feeding-related morbidity and mortality associated with being late preterm. One third of brain growth occurs in the last 6-8 weeks of gestation. The ontogeny of coordinated oral feeding appears to follow a chronological, predictable pattern in preterm neonates. This suggests that neurodevelopmental maturation, rather than experience or learned behavior, is largely responsible for feeding behaviors. The aim of this article is to provide a review of the literature that establishes the relationship between brain development and feeding in the late-preterm infant.

Sex differences in mechanisms and outcome of neonatal hypoxia-ischemia in rodent models: implications for sex-specific neuroprotection in clinical neonatal practice

Clinical findings show that male infants with hypoxic-ischemic injury (HI) fare more poorly than matched females on cognitive outcomes. Rodent models of neonatal hypoxia-ischemia support this difference, with data showing that perinatal brain injury leads to long-term behavioral deficits primarily in male rodents and in female rodents treated with early androgens. Results support the idea that sex-specific gonadal hormones may modulate developmental response to injury and dovetail with overwhelming evidence of developmental androgen effects on typical brain morphology and behavior. However, mechanisms underlying sex differences in response to early brain injury may be more complicated. Specifically, activation of cell death pathways in response to HI may also differ by sex. In females, the preferential activation of the caspase-dependent apoptotic pathway may actually afford greater protection, potentially due to the actions of X-linked inhibitor of apoptosis (XIAP) within this pathway. This contrasts the pattern of preferential activation of the caspase-independent pathway in males. While an integrated model of sex-specific hormonal and genetic modulation of response to early injury remains to be fully elucidated, these findings suggest that infants might benefit from sex-specific neuroprotection following HI injury.

Motor system development of the preterm and low birthweight infant

Despite advances in knowledge and technology, accurate prediction of later neuromotor outcomes for infants born preterm remains somewhat elusive. Here we review some of the most recent findings regarding the differential effects of preterm birth and suboptimal fetal growth on neurodevelopment. Evidence from transcranial magnetic stimulation studies is presented that suggests neuromotor development may more directly influence cognitive outcomes than previously recognised. We discuss the role of neuroplasticity in both exacerbating and improving these postnatal outcomes, and possible therapeutic targets for manipulating this. Finally, some developmental care practices that might affect long-term outcomes for these children are discussed.

Physiologic brain dysmaturity in late preterm infants

Neonatal EEG sleep was used to determine whether differences are expressed between healthy late preterm and full-term (FT) groups. Twenty-seven 24-channel multihour studies were recorded at similar postmenstrual ages (PMA) and analyzed for eight asymptomatic late preterm infants (LPT) compared with 19 healthy FT infants as a preliminary analysis, followed by a comparison of a subset of eight FT infants, matched for gender, race, and PMA. Z scores were performed on data sets from each group pair comparing each of seven EEG/Sleep measures for entire recordings, active sleep (AS) and quiet sleep (QS) segments and artifact-free intervals. Six of seven measures showed differences between the eight LPT and eight matched FT cohort pair comparisons of >0.3; rapid eye movements, arousals during QS, spectral correlations between homologous centrotemporal regions during QS, spectral beta/alpha power ratios during AS and QS, a spectral measure of respiratory regularity during QS, and sleep cycle length. Quantitative neurophysiologic analyses define differences in brain maturation between LPT and FT infants at similar PMA. Altered EEG/Sleep behaviors in the LPT are biomarkers of developmental neuroplasticity involving interconnected neuronal networks adapting to conditions of prematurity for this largest segment of the preterm neonatal population.

Brainstem auditory response findings in late preterm infants in neonatal intensive care unit

AIM

To examine brainstem auditory function at term in late preterm infants admitted to neonatal intensive care unit (NICU).

METHODS

Fifty-two preterm infants, born at 33-36 week gestation, were recruited in an NICU and were studied at term using brainstem auditory evoked response (BAER).

RESULTS

Compared with normal term infants, BAER wave V latency in the NICU preterm infants was increased at 51 and 91/sec (p<0.05, 0.05). Intervals of III-V and I-V were increased at all 21, 51 and 91/sec clicks (p<0.05-0.01), which was more significant at higher than lower rates. Interval ratio of III-V/I-III was increased significantly at 51 and 91/sec (p<0.05 and 0.01). Wave I and III latencies and I-III interval did not differ significantly from normal controls at any click rates. All amplitudes of waves I, III and V amplitude tended to be reduced at higher rates, while wave I amplitude was reduced significantly at 91/sec clicks.

CONCLUSION

There were BAER abnormalities in the NICU late preterm infants, suggesting compromised brainstem auditory function. Compared with a basically normal BAER in low-risk late preterm infants previously reported, the abnormalities suggest that perinatal problems or complications adversely affect the late preterm auditory brainstem.

Developmental delay in moderately preterm-born children at school entry

OBJECTIVE

To determine the prevalence and nature of developmental delay at preschool age in infants born moderately preterm compared with those born full-term and early preterm.

STUDY DESIGN

Parents of 927 moderate preterm infants (32-35(+6) weeks gestation), 512 early preterm infants (<32 weeks gestation) and 544 full-term infants (38-41(+6) weeks gestation) completed the Ages and Stages Questionnaire (ASQ) when the child was aged 43-49 months. We analyzed rates of abnormal ASQ scores and odds ratios for abnormal ASQ scores in both preterm groups compared with the full-term group. We repeated the analyses after adjustment for socioeconomic status, sex, being part of a multiple birth, and small for gestational age status.

RESULTS

Abnormal (ie, >2 SDs below the mean) ASQ total scores were noted in 8.3% of moderate preterm infants, in 4.2% of full-term infants, and in 14.9% of early preterm infants. ORs of abnormal ASQ total scores were 2.1 (95% CI, 1.3-3.4) for moderate preterm infants and 4.0 (95% CI, 2.4-6.5) for early preterm infants. Both moderate and early preterm infants had more frequent problems with fine motor, communication, and personal-social functioning compared with full-term infants. Compared with full-term infants, moderate preterm infants did not have a greater prevalence of problems with gross motor functioning and problem solving, whereas early preterms did. Socioeconomic status, small for gestational age status, and sex were associated with abnormal ASQ scores in moderate preterm infants.

CONCLUSIONS

At preschool age, the prevalence of developmental delay in moderate preterm infants was 2-fold of that in full-term infants and one-half of that in early preterm infants.

Emerging cerebral connectivity in the human fetal brain: an MR tractography study

Cerebral axonal connections begin to develop before birth during radial migration in each brain area. A number of theories are still actively debated regarding the link between neuronal migration, developing connectivity, and gyrification. Here, we used high angular resolution diffusion tractography on postmortem fetal human brains (postconception week (W) 17-40) to document the regression of radial and tangential organization likely to represent migration pathways and the emergence of corticocortical organization and gyrification. The dominant radial organization at W17 gradually diminished first in dorsal parieto-occipital and later in ventral frontotemporal regions with regional variation: radial organization persisted longer in the crests of gyri than at the depths of sulci. The dominant tangential organization of the ganglionic eminence at W17 also gradually disappeared by term, together with the disappearance of the ganglionic eminence. A few immature long-range association pathways were visible at W17, gradually became evident by term. Short-range corticocortical tracts emerged prior to gyrification in regions where sulci later developed. Our results suggest that the regional regression of radial organization and regional emergence of fetal brain connectivity proceeds in general from posterodorsal to anteroventral with local variations.

Children's Brain Development Benefits from Longer Gestation

Disruptions to brain development associated with shortened gestation place individuals at risk for the development of behavioral and psychological dysfunction throughout the lifespan. The purpose of the present study was to determine if the benefit for brain development conferred by increased gestational length exists on a continuum across the gestational age spectrum among healthy children with a stable neonatal course. Neurodevelopment was evaluated with structural magnetic resonance imaging in 100 healthy right-handed 6- to 10-year-old children born between 28 and 41 gestational weeks with a stable neonatal course. Data indicate that a longer gestational period confers an advantage for neurodevelopment. Longer duration of gestation was associated with region-specific increases in gray matter density. Further, the benefit of longer gestation for brain development was present even when only children born full term were considered. These findings demonstrate that even modest decreases in the duration of gestation can exert profound and lasting effects on neurodevelopment for both term and preterm infants and may contribute to long-term risk for health and disease.

The encephalopathy of prematurity: one pediatric neuropathologist's perspective

A major challenge in understanding brain injury in the premature brain is the establishment of the precise human neuropathology at the cellular and molecular levels, as such knowledge is the foundation upon which the elucidation of the cause(s), scientific experimentation, and therapies in the field is by necessity based. In this essay, I provide my perspective as a pediatric neuropathologist upon pathologic studies in the developing human brain itself, including a review of past, present, and future aspects. My focus is upon the path that has brought us to the current recognition that preterm brain injury is a complex of white and gray matter damage that results in the modification of key developmental pathways during a critical period, which in turn defines the adverse clinical outcomes as important as the primary insult itself. The evolution of this recognition, as well as the introduction of the term "encephalopathy of prematurity" for the complex of gray and white matter damage because of acquired and developmental mechanisms, is discussed. Our enhanced understanding of the fundamental neuropathology of the human preterm brain should bring us closer to more effective therapy as the need to prevent and treat injury to developing oligodendrocytes and neurons in combination is appreciated.

Delivery of gastroschisis patients before 37 weeks of gestation is associated with increased morbidities

BACKGROUND

Despite advances in the care of neonates with gastroschisis, patients present with significant morbidities. Preterm delivery of neonates with gastroschisis is often advocated to avoid the intestinal damage that may be sustained with prolonged exposure to amniotic fluid. However, preterm delivery may impose additional morbidities to this disease process.

METHODS

We conducted a retrospective review of patients with gastroschisis born from 1989 to 2007. Demographic and clinical data were collected. Preterm healthy neonates, with gestational age from 26 to 36 weeks, were used as controls.

RESULTS

Preterm infants with gastroschisis had a 14 times higher risk for any of the recorded morbidities. As compared to term neonates with gastroschisis, preterm neonates with gastroschisis had a higher rate of sepsis, longer duration to reach full enteral feedings, and longer length of stay. Although the preterm infants with gastroschisis were less likely to be small for gestational age at birth, they were as likely as the term infants with gastroschisis to have failure to thrive at discharge and had a greater drop in weight percentile during hospitalization.

CONCLUSIONS

Preterm delivery should be avoided because there is no clear benefit to the gut in avoiding derivative injuries. Meticulous attention should be given to the nutritional needs of patients with gastroschisis.

Magnetic resonance imaging and developmental outcome following preterm birth: review of current evidence

Preterm birth is associated with an increased risk of developmental difficulties. Magnetic resonance imaging (MRI) is increasingly being used to identify damage to the brain following preterm birth. It is hoped this information will aid prognostication and identify neonates who would benefit from early therapeutic intervention. Cystic periventricular white matter damage has traditionally been associated with abnormal motor developmental and cerebral palsy, but its presence on MRI does not preclude normal cognitive development. This has led to increasing interest in the identification of diffuse periventricular white matter damage with conventional and sophisticated MRI. However, the correlation between these appearances and developmental outcome remains unclear. Measurements of the size, volumes, and growth rates of many regions of the brain, such as the corpus callosum, ventricular system, cortex, deep grey matter, and cerebellum, are all also altered following preterm birth, but there is insufficient evidence to use this data in the clinical setting. This article is a review of the current evidence on MRI and developmental outcome, suggesting possible indications for the use of MRI following preterm birth.

Resuscitative procedures at birth in late preterm infants

OBJECTIVE

Evaluate the need for resuscitative procedures at birth, in late prematures.

STUDY DESIGN

This prospective cohort study enrolled all liveborn infants from 1 to 30 September 2003, with 34 to 41 weeks of gestation without congenital anomalies, born in 35 public hospitals of 20 Brazilian state capitals. Logistic regression analyzed variables associated with the need for bag and mask ventilation.

RESULT

Of the 10 774 infants studied, 1054 were late preterms and 485 required resuscitative measures. Of the 1054, 338 (32%) received only free-flow oxygen, 143 (14%) were bag and mask ventilated, 27 (3%) were intubated and 10/27 received chest compressions and/or medications. Bag and mask ventilation in late preterms was associated with twin gestation, maternal hypertension, nonvertex presentation, cesarean delivery and lower gestational age.

CONCLUSION

Improving control of maternal hypertension, prolonging gestation for 1 to 2 weeks and restricting operative deliveries could decrease the need of resuscitation of late preterms at birth.

17beta-estradiol protects the neonatal brain from hypoxia-ischemia

Hypoxia-ischemia is relatively common in human infants. Hypoxia-ischemia can occur as a result of complications associated with prematurity or birth, frequently leading to altered brain development and cognitive and behavioral deficits that persist throughout life. Despite the relative frequency of neonatal hypoxic-ischemic encephalopathy, the immature brain sustains relatively less damage than an adult who experiences a similar crisis of oxygen and nutrient deprivation. Therefore, factors may be present that protect the developing brain. During late gestation, the infant brain encounters high levels of the steroid hormone 17beta-estradiol. This observation, combined with evidence supporting 17beta-estradiol as a neuroprotective agent, led us to hypothesize that increasing the basal level of 17beta-estradiol would reduce the amount of hypoxia-ischemia induced injury to the neonatal brain. To test that hypothesis we administered 17beta-estradiol using either a repeated dosing paradigm or a single dose paradigm to immature male and female rats. Here we show that the repeated dosing paradigm (three doses of 17beta-estradiol) provided approximately 70% protection of the hippocampus, basal ganglia, and amygdala. By contrast, a single administration of 17beta-estradiol 24 h prior to hypoxia-ischemia conferred little protection. The only exception was the pyramidal layer of the female hippocampus, which was modestly protected (16% reduction in damage). The protection afforded by the multiple administrations of 17beta-estradiol was similar for females and males, with the only exception being the male amygdala, which displayed less damage than the female amgydala. We conclude that 17beta-estradiol acts as a potent neuroprotective agent against hypoxia-ischemia induced damage to the developing brain, and that pretreating infants at risk for hypoxic-ischemic injury may be advisable.

The neuropathology of acquired pre- and perinatal brain injuries

Acquired pre- and perinatal brain injuries comprise a significant proportion of perinatal neuropathology. They are associated with placental abnormalities, maternal factors, multiple gestations, and preterm labor, as well as with the later development of cerebral palsy and developmental delay. The patterns of perinatal brain injury depend on the etiology (often hypoxic-ischemic) and the timing relative to the development of the fetal nervous system, since the vulnerabilities of gray and white matter differ across postconceptional age and by neuroanatomic site. Nevertheless, characteristic features allow determination of the approximate age and cause of each pattern of injury in the perinatal brain.