Regional brain volume reduction and cognitive outcomes in preterm children at low risk at 9 years of age

Similarities and differences in cerebellar alterations between youth born preterm and youth born with congenital heart disease

Individuals born preterm (PT) or with complex congenital heart disease (CHD) present with comparable prevalence of developmental challenges and patterns of neonatal brain injury. Converging evidence also supports that cerebellar development is altered in PT and in CHD survivors. However, no study compared cerebellar integrity between these two groups. This study aims to assess total and regional cerebellar development between youth born PT or with CHD as compared to controls. Participants aged 16-27 years born before 33 weeks of gestational age or who underwent open-heart surgery for CHD during infancy and a group of healthy term-born controls, underwent a brain MRI. Cerebellums were segmented at the lobular level. Youth born PT or with CHD exhibited a comparable pattern of volume reduction affecting total, regional and lobular cerebellar volumes. After adjusting for total brain volume, no significant differences remained between CHD and controls. Only regions and lobules in the anterior cerebellum remained significantly smaller than controls in the youth born PT. Atypical cerebellar development is present in youth born PT and in youth with CHD. However, our results suggested that premature exposure to the extra-uterine environment alters cerebellar development selectively while the cumulative effect of CHD globally hinders brain development.

Cerebellar Development and the Burden of Prematurity

The role of the cerebellum in the neurodevelopmental outcomes of preterm infants has often been neglected. However, accumulating evidence indicates that normal cerebellar development is disrupted by prematurity-associated complications causing cerebellar injury and by prematurity itself. This hampers not only the normal development of motor skills and gait, but also cognitive, language, and behavioral development, collectively referred to as "developmental cognitive affective syndrome." In this comprehensive narrative review, we provide the results of an extensive literature search in PubMed and Embase to summarize recent evidence on altered cerebellar development in premature infants, focusing on neuroimaging findings, its causative factors and its impact on long-term neurodevelopmental outcomes.

Long-term brain structural and cognitive outcomes in a low-risk preterm-born sample

Prematurity has been related to altered brain structure and cognition, and so our aim was to describe them in the absence of major structural brain injury following low-risk preterm birth during adolescence and young adulthood. The sample consisted of 250 participants, 132 of whom were low-risk preterm (30-36 weeks' gestational age) and 118 were full-term individuals (37-42 weeks' gestational age), aged between 16 and 38 years old. All participants underwent an extensive neuropsychological assessment. T1- and diffusion-weighted MRI images of 33 low-risk preterm and 31 full-term young adults (20-32 years old) were analyzed. No differences were found in terms of general cognitive functioning score or current socioeconomic status; however, the low-risk preterm group obtained lower scores in phonetic and semantic fluencies, and theory of mind. Significant reductions were identified in the thalamus volume as well as thicker cortex in the inferior temporal gyrus in the low-risk preterm group. Low-risk preterm young adults evidenced greater regional AD and MD compared to the full-term sample; while low-risk preterm group showed lower mean NDI and ODI (FWE-corrected, p < 0.05). Being born preterm is associated with poorer performance in various cognitive domains (i.e., phonetic and semantic fluencies, and theory of mind) later in life, along with differences in normative structural brain development in inferior temporal gyrus and regional white matter microstructure.

Perinatal influences on academic achievement and the developing brain: a scoping systematic review

Introduction and methods

In this PRISMA-compliant systematic review, we identify and synthesize the findings of research in which neuroimaging and assessments of achievement have been used to examine the relationships among aspects of developmental programming, neurodevelopment, and achievement in reading and mathematics.

Results

Forty-seven studies met inclusion criteria. The majority examined the impact of prematurity (n = 32) and prenatal alcohol exposure (n = 13). Several prematurity studies reported a positive correlation between white-matter integrity of callosal fibers and executive functioning and/or achievement, and white matter properties were consistently associated with cognitive and academic performance in preterm and full-term children. Volumetric studies reported positive associations between academic and cognitive abilities and white and gray matter volume in regions such as the insula, putamen, and prefrontal lobes. Functional MRI studies demonstrated increased right-hemispheric language processing among preterm children. Altered activation of the frontoparietal network related to numerical abilities was also reported. Prenatal alcohol exposure studies reported alterations in white matter microstructure linked to deficits in cognitive functioning and academic achievement, including mathematics, reading, and vocabulary skills. Volumetric studies reported reductions in cerebral, cerebellar, and subcortical gray matter volumes associated with decreased scores on measures of executive functioning, attention, working memory, and academic performance. Functional MRI studies demonstrated broad, diffuse activation, reduced activation in canonical regions, and increased activation in non-canonical regions during numeric tasks.

Discussion

A preponderance of studies linked prematurity and prenatal alcohol exposure to altered neurodevelopmental processes and suboptimal academic achievement. Limitations and recommendations for future research are discussed.

Systematic review registration

Identifier: DOI 10.17605/OSF.IO/ZAN67.

Meta-Analysis of Hippocampal Volume and Episodic Memory in Preterm and Term Born Individuals

Preterm birth (< 37 weeks gestation) has been associated with memory deficits, which has prompted investigation of possible alterations in hippocampal volume in this population. However, existing literature reports varying effects of premature birth on hippocampal volume. Specifically, it is unclear whether smaller hippocampal volume in preterm-born individuals is merely reflective of smaller total brain volume. Further, it is not clear if hippocampal volume is associated with episodic memory functioning in preterm-born individuals. Meta-analysis was used to investigate the effects of premature birth on hippocampal volume and episodic memory from early development to young adulthood (birth to 26). PubMed, PsychINFO, and Web of Science were searched for English peer-reviewed articles that included hippocampal volume of preterm and term-born individuals. Thirty articles met the inclusion criteria. Separate meta-analyses were used to evaluate standardized mean differences between preterm and term-born individuals in uncorrected and corrected hippocampal volume, as well as verbal and visual episodic memory. Both uncorrected and corrected hippocampal volume were smaller in preterm-born compared to term-born individuals. Although preterm-born individuals had lower episodic memory performance than term-born individuals, the limited number of studies only permitted a qualitative review of the association between episodic memory performance and hippocampal volume. Tested moderators included mean age, pre/post-surfactant era, birth weight, gestational age, demarcation method, magnet strength, and slice thickness. With this meta-analysis, we provide novel evidence of the effects of premature birth on hippocampal volume.

Relationship of early brain growth pattern measured by ultrasound with neurological outcome at two years of age in very low birth weight infants

The purpose of this study is to define the impact of early brain growth trajectory in very low birth weight infants (VLBWI) on neurological prognosis at 2 years, assessed using sequential ultrasound (US) scans. This is a prospective cohort study with consecutive inclusion of VLBWI ≤ 32 weeks gestational age and ≤ 1500 g at birth. Total brain volume (TBV) was assessed using sequential 3D-US from birth to discharge. Prognosis at 2 years (corrected age) was assessed using the Bayley Scales of Infant and Toddler Development Third Edition. TBV showed slower growth with postmenstrual age (PMA) in those VLBWI who had an adverse cognitive prognosis compared to those with good cognitive prognosis (mean difference in TBV between prognostic groups from 4.56 cm3 at 28 weeks to 42.58 cm3 at 43 weeks) as well as in those with adverse language prognosis (mean difference in TBV from 2.21 cm3 at 28 weeks to 26.98 cm3 at 43 weeks) although other variables showed more impact than TBV on language prognosis (gestational age at birth, brain injury at term, and socioeconomic status). No association was found between TBV and motor prognosis. Brain growth rate was also significantly higher in those VLBWI who presented good cognitive scores (18.78 + (0.33 × (PMA-33)) cm3/week) compared to those with adverse cognitive outcome (13.73 + (0.64 × (PMA-33)) cm3/week).  Conclusion: Early altered brain growth is associated with poor cognitive prognosis at 2 years of age. Using sequential US monitoring, we can detect early brain growth deviation in patients who will have adverse cognitive outcomes. What is known: • The prediction of neurodevelopmental outcome of VLBWI is mostly based on the presence of brain injury in US and structural magnetic resonance imaging (MRI) at term. • Some studies have related brain volume measured on MRI at term with neurodevelopment outcome. What is new: • VLBWI with adverse cognitive prognosis at two years of age present smaller brain volumes detectable by sequential US during NICU admission. • Brain volume can be estimated from 2D and 3D US and has prognostic value in VLBWI.

Neurobiological perspective on the development of executive functions

Executive functions are a set of top-down cognitive processes necessary for emotional self-regulation and goal-directed behaviour supporting, among others, academic abilities. Premature infants are at high risk for subsequent cognitive, psychosocial, or behavioural problems even in the absence of medical complications and in spite of normal brain imaging. Given that this is a sensitive period of brain growth and maturation, these factors may place preterm infants at high risk for executive function dysfunction, disrupted long-term development, and lower academic achievements. Therefore, careful attention to interventions at this age is essential for intact executive functions and academic development.

Intelligence Quotient (IQ) in school-aged preterm infants: A systematic review

Preterm birth (before 37 weeks of gestational age) is associated with certain risks to child development. The aim of this systematic review was to summarize available and updated empirical evidence on prematurity as a risk factor for cognitive development in school age. Thus, we attempted to identify similarities and differences with the full-term population and to point out possible risk or protective factors among the biological, psychosocial and family variables. The conceptualization and methodology of this review followed the PRISMA recommendations. The search was carried out in Web of Science, Scopus, PsycInfo, and Dialnet databases, in May 2022. The search was limited to journal articles, published between 2012 and 2022, in English and Spanish. Research articles selected were those focused on the intelligence quotient (IQ) of preterm children aged 6-12 years. The review included studies with cross-sectional or longitudinal cohorts, compared to a control group of children born at term or to standardized scales. The quality of evidence of the selected studies was verified with the Mixed Methods Appraisal Tool (MMAT). The initial search identified 1,040 articles. Forty articles met the inclusion criteria and were finally included in this review. These studies involved 5,396 preterm children from 37 different cohorts. Despite the diversity found among the results, in general, total IQ scores were within the normative mean for premature children; however, compared to their full-term peers, these scores were lower. The most studied variables in relation to IQ are perinatal (e.g., gestational age and birth weight) and family (e.g., socioeconomic level and education level of the mother). Recent studies corroborate that premature birth affects cognitive development in school age, and identify associated perinatal and family variables.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=337371; identifier: CRD42022337371.

Brain structural parameters correlate with University Selection Test outcomes in Chilean high school graduates

How well students learn and perform in academic contexts is a focus of interest for the students, their families, and the entire educational system. Although evidence has shown that several neurobiological factors are involved in scholastic achievement (SA), specific brain measures associated with academic outcomes and whether such associations are independent of other factors remain unclear. This study attempts to identify the relationship between brain structural parameters, and the Chilean national University Selection Test (PSU) results in high school graduates within a multidimensional approach that considers socio-economic, intellectual, nutritional, and demographic variables. To this end, the brain morphology of a sample of 102 students who took the PSU test was estimated using Magnetic Resonance Imaging. Anthropometric parameters, intellectual ability (IA), and socioeconomic status (SES) were also measured. The results revealed that, independently of sex, IA, gray matter volume, right inferior frontal gyrus thickness, and SES were significantly associated with SA. These findings highlight the role of nutrition, health, and socioeconomic variables in academic success.

Different Brain Phenotypes in Magnetic Resonance Imaging of Healthy Children after Prenatal Insults

In this study, we used magnetic resonance imaging (MRI) to identify the different brain phenotypes within apparently healthy children and to evaluate whether these phenotypes had different prenatal characteristics. We included 65 healthy children (mean age, 10 years old) with normal neurological examinations and without structural abnormalities. We performed cluster analyses to identify the different brain phenotypes in the brain MRI images. We performed descriptive analyses, including demographic and perinatal characteristics, to assess the differences between the clusters. We identified two clusters: Cluster 1, or the “small brain phenotype” (n = 44), which was characterized by a global reduction in the brain volumes, with smaller total intracranial volumes (1044.53 ± 68.37 vs. 1200.87 ± 65.92 cm3 (p < 0.001)), total grey-matter volumes (644.65 ± 38.85 vs. 746.79 ± 39.37 cm3 (p < 0.001)), and total white-matter volumes (383.68 ± 40.17 vs. 443.55 ± 36.27 cm3 (p < 0.001)), compared with Cluster 2, or the “normal brain phenotype” (n = 21). Moreover, almost all the brain areas had decreased volumes, except for the ventricles, caudate nuclei, and pallidum areas. The risk of belonging to “the small phenotype” was 82% if the child was preterm, 76% if he/she was born small for his/her gestational age and up to 80% if the mother smoked during the pregnancy. However, preterm birth appears to be the only substantially significant risk factor associated with decreased brain volumes.

Of differing methods, disputed estimates and discordant interpretations: the meta-analytical multiverse of brain volume and IQ associations

Brain size and IQ are positively correlated. However, multiple meta-analyses have led to considerable differences in summary effect estimations, thus failing to provide a plausible effect estimate. Here we aim at resolving this issue by providing the largest meta-analysis and systematic review so far of the brain volume and IQ association (86 studies; 454 effect sizes from k = 194 independent samples; N = 26 000+) in three cognitive ability domains (full-scale, verbal, performance IQ). By means of competing meta-analytical approaches as well as combinatorial and specification curve analyses, we show that most reasonable estimates for the brain size and IQ link yield r-values in the mid-0.20s, with the most extreme specifications yielding rs of 0.10 and 0.37. Summary effects appeared to be somewhat inflated due to selective reporting, and cross-temporally decreasing effect sizes indicated a confounding decline effect, with three quarters of the summary effect estimations according to any reasonable specification not exceeding r = 0.26, thus contrasting effect sizes were observed in some prior related, but individual, meta-analytical specifications. Brain size and IQ associations yielded r = 0.24, with the strongest effects observed for more g-loaded tests and in healthy samples that generalize across participant sex and age bands.

PM2.5 exposure increases the risk of preterm birth in pre-pregnancy impaired fasting glucose women: A cohort study in a Southern province of China

Previous studies have indicated maternal exposure to particles with aerodynamic diameter <2.5 μm (PM_2.5) is associated with preterm birth (PTB). However, no study has investigated this effect in pre-pregnancy impaired fasting glucose (IFG) women. This study aimed to differentiate the effects of maternal PM_2.5 exposure on PTB between pre-pregnancy IFG and normoglycemia women, and to further identify the susceptible window. This cohort study was conducted between January 2014 and December 2017 in 21 Chinese cities. All the recruited women received pre-pregnancy fasting serum glucose (FSG) tests and were followed up for their delivery outcomes. The PM_2.5 exposures were estimated by the daily air pollution concentrations of the nearby monitors. Women with FSG below 7.0 mmol/L were included in the analysis. We employed the Cox proportional hazards models to examine whether PM_2.5 exposure was associated with PTB. 237957 women were included and 7055 (3.0%) of them were pre-pregnancy IFG. During the entire pregnancy, we found 24.1% (HR = 1.241; 95% CI: 1.069, 1.439), 61.8% (HR = 1.618; 95% CI: 1.311, 1.997) and 18.6% (HR = 1.186; 95% CI: 1.004, 1.402) of increases in risk for all PTB, early PTB (20-33 gestational weeks) and late PTB (34-36 gestational weeks) among the pre-pregnancy IFG women, and 15.9% (HR = 1.159; 95% CI: 1.127, 1.192), 33.9% (HR = 1.339; 95% CI: 1.255, 1.430) and 13.2% (HR = 1.132; 95% CI: 1.098, 1.168) of increases in risk for all PTB, early PTB and late PTB among the normoglycemia women, with each 10 μg/m³ increment of PM_2.5 exposure, respectively. Furthermore, PM_2.5 exposure had the strongest effect on all PTB during trimester 1 (0-12 gestational weeks) among the pre-pregnancy IFG women, compared with the less strong effect during trimester 1 among the normoglycemia women. In conclusion, pre-pregnancy IFG increases the risk of PTB attributed to PM_2.5, especially during trimester 1. Moreover, the effects of PM_2.5 are greater on early PTB than late PTB for both pre-pregnancy IFG and normoglycemia women.

Exploring the distribution of grey and white matter brain volumes in extremely preterm children, using magnetic resonance imaging at term age and at 10 years of age

OBJECTIVES

To investigate differences in brain volumes between children born extremely preterm and term born controls at term age and at 10 years of age.

STUDY DESIGN

Children born extremely preterm (EPT), up to 26 weeks and 6 days gestational age, in Stockholm between January 1 2004 to March 31 2007 were included in this population-based cohort study. A total of 45 EPT infants were included at term age and 51 EPT children were included at 10 years of age. There were 27 EPT children included at both time points. Two different control groups were recruited; 15 control infants were included at term age and 38 control children at 10 years of age. The primary outcomes were the grey and white matter volumes. Linear regression, adjusted for intracranial volume and sex, was used.

RESULTS

At term age, the extremely preterm infants had significantly smaller grey matter volume compared to the control infants with an adjusted mean difference of 5.0 cm3 and a 95% confidence interval of -8.4 to -1.5 (p = 0.004). At 10 years of age the extremely preterm children had significantly smaller white matter volume compared to the control children with an adjusted mean difference of 6.0 cm3 and a 95% confidence interval of -10.9 to -1.0 (p = 0.010).

CONCLUSION

Extremely preterm birth was associated with reduced grey matter volume at term age and reduced white matter volume at 10 years of age compared to term born controls.

Cerebellar injury in premature neonates: Imaging findings and relationship with outcome

Cerebellar hemorrhagic injury (CHI) is a common complication of preterm birth. There are now many studies that have investigated the developmental consequences of CHI. This review summarizes the present state of evidence regarding the outcomes of prematurity related CHI, with a particular focus on the neuroimaging characteristics associated with adverse outcomes. Studies published to date suggest that the severity of functional deficits is dependent on injury size and topography. However, the unique contribution of the CHI to outcomes still needs to be further investigated to ensure optimal prognostic counseling.

Cerebellar volumes and language functions in school-aged children born very preterm

BACKGROUND

Volumes of cerebellar posterior lobes have been associated with cognitive skills, such as language functioning. Children born very preterm (VPT) often have language problems. However, only total cerebellar volume has been associated with language functioning, with contradicting results. The objective of this study was to ascertain whether total cerebellar structures or specific posterior lobular structures are associated with language ability of school-aged VPT children.

METHODS

This is a prospective cohort study of 42 school-aged VPT children without major handicaps. Structural MRI was performed and the cerebellum segmentation pipeline was used for segmentation of separate lobules. Narrative retelling assessment was performed and language content and language structure scores were extracted. Linear regression analyses were used to associate language scores with whole gray matter (GM) cerebellar volume and right Crus I+II GM volume.

RESULTS

Whole cerebellar GM volume was not significantly associated with language content nor with language structure; however, right Crus I+II GM volume was significantly associated with language content (β = 0.192 (CI = 0.033, 0.351), p = 0.020).

CONCLUSIONS

GM volume of Crus I+II appears to be associated with language functions in school-aged VPT children without major handicaps, while whole cerebellar volume is not. This study showed the importance of studying cerebellar lobules separately, rather than whole cerebellar volume only, in relation to VPT children's language functions.

IMPACT

GM volume of Crus I+II is associated with semantic language functions in school-aged very preterm children without overt brain injury, whereas whole cerebellar volume is not. This study showed the importance of studying cerebellar lobules separately, rather than whole cerebellar volume only, in relation to very preterm children's language functions. This study might impact future research in very preterm children. Lobular structures rather than whole cerebellar structures should be the region of interest in relation to language functions.

Combining Kangaroo Care and Live-Performed Music Therapy: Effects on Physiological Stability and Neurological Functioning in Extremely and Very Preterm Infants

Interventions such as kangaroo care (KC) and live-performed music therapy (LPMT), are increasingly used to facilitate stress reduction in neonates. This study aims to investigate the effect of combining the two on physiological responses and neurological functioning in very preterm infants. Infants received six sessions of LPMT. KC was added to one LPMT session. Physiological responses included heart rate, respiratory rate and oxygen saturation. We videotaped infants for 30 min before and after two sessions to assess general movements (GMs). We included 17 infants, gestational age median 26.0 weeks (IQR 25.6–30.6 weeks), of whom six were males. Combined interventions showed a decrease in heart rate from mean 164 bpm before to 157 bpm during therapy, p = 0.001. Oxygen saturation levels increased during combination therapy from median 91.4% to 94.5%, p = 0.044. We found no effects of LPMT or combined interventions on GMs. Infants with a postnatal age (PNA) <7 days generally seem to display less optimal GMs after therapy compared with infants with a PNA >7 days. In conclusion, combining interventions is equally beneficial for physiological stability and neurological functioning as LPMT alone. Future studies should focus on the effects of this combination on parent-infant bonding.

Intelligence and executive function of school-age preterm children in function of birth weight and perinatal complication

AIM

Assessment of intelligence and executive function in 9-10-year-old preterm children as compared to a full-term comparison group and to reveal the background of the individual differences in the outcomes by analyzing the effects of perinatal and social-economic factors.

METHOD

Seventy-two preterm children (divided into two groups: 32 extremely low birth weight, 40 very low birth weight) and a matched group of 33 healthy full-term children, aged 9-10 years, were tested using the Wechsler Intelligence Scales for Children (WISC-IV) and digital versions of tasks measuring executive function. As background information perinatal variables and maternal education were entered in the analysis.

RESULTS

In the WISC-IV all three groups performed in the normal range. The preterm children, particularly the ELBW subgroup, scored significantly lower than the full-term comparison group in several outcome measures. Behind the group means there were massive scatters of the individual scores. Lower maternal education, male gender, and bronchopulmonary dysplasia (BPD) increased the risk for performance deficits.

CONCLUSION

Low-to-moderate risk preterm children as groups are disadvantaged in the development of intelligence and executive function as compared to healthy full-term children even until school-age. However, with appropriate protective factors they may have chances to develop comparably with their full-term, non-risk counterparts.

Functional Connectivity Network Disruption Underlies Domain-Specific Impairments in Attention for Children Born Very Preterm

Attention problems are common in school-age children born very preterm (VPT; < 32 weeks gestational age), but the contribution of aberrant functional brain connectivity to these problems is not known. As part of a prospective longitudinal study, brain functional connectivity (fc) was assessed alongside behavioral measures of selective, sustained, and executive attention in 58 VPT and 65 full-term (FT) born children at corrected-age 12 years. VPT children had poorer sustained, shifting, and divided attention than FT children. Within the VPT group, poorer attention scores were associated with between-network connectivity in ventral attention, visual, and subcortical networks, whereas between-network connectivity in the frontoparietal, cingulo-opercular, dorsal attention, salience and motor networks was associated with attention functioning in FT children. Network-level differences were also evident between VPT and FT children in specific attention domains. Findings contribute to our understanding of fc networks that potentially underlie typical attention development and suggest an alternative network architecture may help support attention in VPT children.

Estimated whole-brain and lobe-specific radiofrequency electromagnetic fields doses and brain volumes in preadolescents

OBJECTIVE

To assess the association between estimated whole-brain and lobe-specific radiofrequency electromagnetic fields (RF-EMF) doses, using an improved integrated RF-EMF exposure model, and brain volumes in preadolescents at 9-12 years old.

METHODS

Cross-sectional analysis in preadolescents aged 9-12 years from the Generation R Study, a population-based birth cohort set up in Rotterdam, The Netherlands (n = 2592). An integrated exposure model was used to estimate whole-brain and lobe-specific RF-EMF doses (mJ/kg/day) from different RF-EMF sources including mobile and Digital Enhanced Cordless Telecommunications (DECT) phone calls, other mobile phone uses than calling, tablet use, laptop use, and far-field sources. Whole-brain and lobe-specific RF-EMF doses were estimated for all RF-EMF sources together (i.e. overall) and for three groups of RF-EMF sources that lead to a different pattern of RF-EMF exposure. Information on brain volumes was extracted from magnetic resonance imaging scans.

RESULTS

Estimated overall whole-brain RF-EMF dose was 84.3 mJ/kg/day. The highest overall lobe-specific dose was estimated in the temporal lobe (307.1 mJ/kg/day). Whole-brain and lobe-specific RF-EMF doses from all RF-EMF sources together, from mobile and DECT phone calls, and from far-field sources were not associated with global, cortical, or subcortical brain volumes. However, a higher whole-brain RF-EMF dose from mobile phone use for internet browsing, e-mailing, and text messaging, tablet use, and laptop use while wirelessly connected to the internet was associated with a smaller caudate volume.

CONCLUSIONS

Our results suggest that estimated whole-brain and lobe-specific RF-EMF doses were not related to brain volumes in preadolescents at 9-12 years old. Screen activities with mobile communication devices while wirelessly connected to the internet lead to low RF-EMF dose to the brain and our observed association may thus rather reflect effects of social or individual factors related to these specific uses of mobile communication devices. However, we cannot discard residual confounding, chance finding, or reverse causality. Further studies on mobile communication devices and their potential negative associations with brain development are warranted, regardless whether associations are due to RF-EMF exposure or to other factors related to their use.

Language functions deserve more attention in follow-up of children born very preterm

BACKGROUND

Language is a complex neurodevelopmental phenomenon. Approximately 45% of children born very preterm (VP) show mild-to-severe language problems throughout childhood. Nevertheless, in most hospitals in Europe language functions are not routinely assessed at follow-up.

OBJECTIVE

To give clear indications for extensive language assessment in school-aged children born VP, based on routinely assessed intelligence and behavioral problems.

METHOD

Language functions of 63 10-year-old children born VP (<32 weeks' gestation) without major handicaps were compared to their intellectual and executive functions and behavioral problems. Using multiple linear regression analyses, the predictive value of perinatal factors and the association with neurodevelopmental factors of low language were measured.

RESULTS

The mean language score was significantly lower than the verbal intelligent quotient (VIQ; mean difference = 6.4, p < .001, d=.48) and the mean vocabulary knowledge (mean difference = 9.3, p < .001, d=.70). Besides, VIQ (β = .649, p = .001) and performance IQ (PIQ; β = .260, p = .035) were significantly associated with language scores. Significant predictors of language scores were number of days of assisted ventilation (β = -.592, p = .015) and mother's vocabulary knowledge (β =.473, p = .014), rather than mother's educational level (β =.139, p = .956).

CONCLUSIONS

Children born VP had language problems that were not expected from their significantly higher VIQ and vocabulary knowledge. Clinicians assessing these children should be aware of possible language problems, which cannot be detected with a simple vocabulary task. Our findings provide evidence of the need for adequate language assessments by a speech-language pathologist in children born VP, especially in those with VIQ scores in the low average range.

A prospective population-based study of gestational vitamin D status and brain morphology in preadolescents

Low vitamin D level during pregnancy has been associated with adverse neurodevelopmental outcomes such as autism spectrum disorders (ASD) in children. However, the underlying neurobiological mechanism remains largely unknown. This study investigated the association between gestational 25-hydroxyvitamin D [25(OH)D] concentration and brain morphology in 2597 children at the age of 10 years in the population-based Generation R Study. We studied both 25(OH)D in maternal venous blood in mid-gestation and in umbilical cord blood at delivery, in relation to brain volumetric measures and surface-based cortical metrics including cortical thickness, surface area, and gyrification using linear regression. We found exposure to higher maternal 25(OH)D concentrations in mid-gestation was associated with a larger cerebellar volume in children (b ​= ​0.02, 95%CI 0.001 to 0.04), however this association did not remain after correction for multiple comparisons. In addition, children exposed to persistently deficient (i.e., <25 ​nmol/L) 25(OH)D concentration from mid-gestation to delivery showed less cerebral gray matter and white matter volumes, as well as smaller surface area and less gyrification at 10 years than those with persistently sufficient (i.e., ≥50 ​nmol/L) 25(OH)D concentration. These results suggest temporal relationships between gestational vitamin D concentration and brain morphological development in children.

Gestational 1-nitropyrene exposure causes gender-specific impairments on postnatal growth and neurobehavioral development in mice

1-Nitropyrene (1-NP), a typical nitrated polycyclic aromatic hydrocarbon, is widely distributed in the environment and is well known for its mutagenic effects. Recently, we found that gestational 1-NP exposure induced fetal growth restriction. In this study, we further evaluated the effect of in utero 1-NP exposure on postnatal growth and neurobehavioral development in the offspring. Pregnant mice were administered with 1-NP (10 μg/kg) by gavage daily in late pregnancy (GD13-GD17). The body weight of each offspring was measured from PND1 to 12 weeks postpartum. Exploration and anxiety related activities were detected by open-field test at 6 weeks postpartum. Learning and memory were assessed by Morris Water Maze at 7 weeks postpartum. And depressive-like behaviors were estimated by sucrose preference test at 10 weeks postpartum. Significant body weight reduction was observed in 1-NP-exposed female offspring at PND1, PND14 and PND21 while the lower body weight was only found at PND1 for 1-NP-exposed male offspring. Exploration and anxiety activities at puberty, and depressive-like behavior in adulthood were not disturbed in offspring prenatally exposed to 1-NP. Interestingly, spatial learning and memory ability at puberty was impaired in females but not in males prenatally exposed to 1-NP. These findings suggest that gestational 1-NP exposure delays postnatal growth and impaired neurobehavioral development in a gender-dependent manner.

Rapid Postnatal Adaptation of Neurodevelopment in Pigs Born Late Preterm

Preterm birth interrupts intrauterine brain growth and maturation and may induce a delay in postnatal neurodevelopment. Such developmental delays can result from the reduced fetal age at birth, together with the clinical compli-cations of preterm birth (e.g., hypoxia, ischemia, and inflammation). We hypothesized that late preterm birth, inducing only mild clinical complications, has minimal effects on brain-related outcomes such as motor function and behavior. Using the pig as a model for late preterm infants, piglets were cesarean delivered preterm (90%, 106 days gestation) or at full term, reared by identical procedures, and euthanized for tissue collection at birth or after 11 days (e.g., term-corrected age for preterm pigs). Clinical variables and both structural and functional brain endpoints were assessed. The preterm pigs were slow to get on their feet, gained less weight (-30%), and had a higher cerebral hydration level and blood-to-cerebrospinal fluid permeability than the term pigs. At term-corrected age (11 days), the absolute weight of the brain and the weights of its regions were similar between 11-day-old preterm and newborn term pigs, and both were lower than in 11-day-old term pigs. Postnatally, physical activity and movements in an open field were similar, except that preterm pigs showed a reduced normalized stride length and increased normalized maximum stride height. Perinatal brain growth is closely associated with advancing postconceptional age in pigs, and late preterm birth is initially associated with impaired brain growth and physical activity. Postnatally, neuromuscular functions mature rapidly and become similar to those in term pigs, even before term-corrected age. Neuromuscular functions and behavior may show rapid postnatal adaptation to late preterm birth in both pigs and infants.

Ambient PM2.5 and birth outcomes: Estimating the association and attributable risk using a birth cohort study in nine Chinese cities

BACKGROUND

Previous studies have reported that maternal exposure to particles with aerodynamic diameter <2.5 μm (PM_2.5) is associated with birth outcomes. However, a multicity birth cohort study has not been conducted in China, and the attributable fraction of adverse birth outcomes due to PM_2.5 exposure remains unknown.

METHODS

We examined associations in a birth cohort of 1,455,026 mother-and-live-birth pairs who were followed up from the first hospital visit for pregnancy until the birth of the baby during 2014-2017 in nine cites of the Pearl River Delta (PRD) region, China. The PM_2.5 exposures were estimated based on the air pollution concentrations of the nearby monitors. Cox proportional hazards regressions were employed to examine the associations.

RESULTS

We found 1% (HR = 1.01; 95% CI: 1.00, 1.02), 6% (HR = 1.06; 95% CI: 1.05, 1.07), and 7% (HR = 1.07; 95% CI: 1.06, 1.08) increases in risk of PTB and 20% (HR = 1.20; 95% CI: 1.18, 1.22), 18% (HR = 1.18; 95% CI: 1.15, 1.20), and 20% (HR = 1.20; 95% CI: 1.17, 1.23) increases in risk of LBW, with each 10 μg/m³ increase in PM_2.5 from trimester 1 to trimester 3, respectively. For PTB, highest HRs were observed during trimester 3, as for LBW, stronger effect were observed during trimester 1 and trimester 3. We further estimated that 7.84% (95% CI: 6.21%, 9.50%) of PTB and 14.85% (95% CI: 13.00%, 16.61%) of the LBW cases could be attributable to PM_2.5 exposure during the third trimester.

CONCLUSION

The results indicate that maternal PM_2.5 exposure is a risk factor for both LBW and PTB, and responsible for considerable burdens of PTB and LBW in the Pearl River Delta region.

Maternal air pollution exposure and preterm birth in Wuxi, China: Effect modification by maternal age

BACKGROUND

Numerous studies have investigated prenatal air pollution and shown that air pollutants have adverse effect on birth outcomes. However, which trimester was the most sensitive and whether the effect was related to maternal age is still ambiguous.

OBJECTIVES

This study aims to explore the association between maternal air pollution exposure during pregnancy and preterm birth, and if this relationship is modified by maternal age.

METHODS

In this retrospective cohort study, we examine the causal relationship of prenatal exposure to air pollutants including particulate matters, which are less than 10 µm (PM10), and ozone (O3), which is one of the gaseous pollutants, on preterm birth by gestational age. A total of 6693 pregnant women were recruited from Wuxi Maternal and Child Health Care Hospital. The participants were dichotomized into child-bearing age group (< 35 years old) and advanced age group (> = 35 years old) in order to analyze the effect modification by maternal age. Logistic and linear regression models were performed to assess the risk for preterm birth (gestational age < 37 weeks) caused by prenatal air pollution exposure.

RESULTS

With adjustment for covariates, the highest level of PM10 exposure significantly increased the risk of preterm birth by 1.42-fold (95% CI: 1.10, 1.85) compared those with the lowest level in the second trimester. Trimester-specific PM10 exposure was positively associated with gestational age, whereas O3 exposure was associated with gestational age in the early pregnancy. When stratified by maternal age, PM10 exposure was significantly associated with an increased risk of preterm birth only in the advanced age group during pregnancy (OR:2.15, 95% CI: 1.13, 4.07). The results suggested that PM10 exposure associated with preterm birth was modified by advanced maternal age (OR interaction = 2.00, 95% CI: 1.02, 3.91, Pinteraction = 0.032).

CONCLUSION

Prenatal air pollution exposure would increase risk of preterm birth and reduced gestational age. Thus, more attention should be paid to the effects of ambient air pollution exposure on preterm birth especially in pregnant women with advanced maternal age.

Preterm birth disrupts cerebellar development by affecting granule cell proliferation program and Bergmann glia

Preterm birth is a leading cause of long-term motor and cognitive deficits. Clinical studies suggest that some of these deficits result from disruption of cerebellar development, but the mechanisms that mediate cerebellar abnormalities in preterm infants are largely unknown. Furthermore, it remains unclear whether preterm birth and precocious exposure to the ex-utero environment directly disrupt cerebellar development or indirectly by increasing the probability of cerebellar injury, including that resulting from clinical interventions and protocols associated with the care of preterm infants. In this study, we analyzed the cerebellum of preterm pigs delivered via c-section at 91% term and raised for 10 days, until term-equivalent age. The pigs did not receive any treatments known or suspected to affect cerebellar development and had no evidence of brain damage. Term pigs sacrificed at birth were used as controls. Immunohistochemical analysis revealed that preterm birth did not affect either size or numbers of Purkinje cells or molecular layer interneurons at term-equivalent age. The number of granule cell precursors and Bergmann glial fibers, however, were reduced in preterm pigs. Preterm pigs had reduced proliferation but not differentiation of granule cells. qRT-PCR analysis of laser capture microdissected external granule cell layer showed that preterm pigs had a reduced expression of Ccnd1 (Cyclin D1), Ccnb1 (Cyclin B1), granule cell master regulatory transcription factor Atoh1, and signaling molecule Jag1. In vitro rescue experiments identified Jag1 as a central granule cell gene affected by preterm birth. Thus, preterm birth and precocious exposure to the ex-utero environment disrupt cerebellum by modulating expression of key cerebellar developmental genes, predominantly affecting development of granule precursors and Bergmann glia.

Language outcome related to brain structures in school-aged preterm children: A systematic review

Preterm children often have language problems. This atypical language development is probably due to atypical brain development. We conducted a systematic review to provide an overview of the extensive and diverse scientific literature on the relations between language outcome and underlying brain structures in school-aged preterm-born children. Embase, Medline Ovid, Web of Science, Cochrane central and Google scholar were searched for relevant studies. Inclusion criteria were: cases are school-aged preterm children; structural MRI (T1- and T2-weighted sequences) or DTI used in combination with a neurocognitive language test; publication in an English-language peer-reviewed journal. Correlational measures between language scores and brain volume or fractional anisotropy of a brain structure were extracted. 23 studies were included. The relations between oral language, verbal fluency and/or written language and MRI/DTI measurements of white matter, gray matter, cerebellum, corpus callosum and/or the fasciculi are presented. Oral language skills and verbal fluency appear to be related to the corpus callosum. Oral language skills are also related to the uncinate fasciculus. There seems to be no clear relation between cerebellar development and verbal fluency skills. Not one single brain area is responsible for atypical language development, but several brain areas and their connections are essential. For future research it is recommended to relate brain areas to oral language skills on a microstructural level in preterm children. We also recommend to use language tests in which it is possible to distinguish between several language domains, such as perceptive and expressive language.