Term-born Controls Research Articles

Multiple imputation for missing data in a longitudinal cohort study: a tutorial based on a detailed case study involving imputation of missing outcome data

Multiple imputation (MI), a two-stage process whereby missing data are imputed multiple times and the resulting estimates of the parameter(s) of interest are combined across the completed datasets, is becoming increasingly popular for handling missing data. However, MI can result in biased inference if not carried out appropriately or if the underlying assumptions are not justifiable. Despite this, there remains a scarcity of guidelines for carrying out MI. In this paper we provide a tutorial on the main issues involved in employing MI, as well as highlighting some common pitfalls and misconceptions, and areas requiring further development. When contemplating using MI we must first consider whether it is likely to offer gains (reduced bias or increased precision) over alternative methods of analysis. Once it has been decided to use MI, there are a number of decisions that must be made during the imputation process; we discuss the extent to which these decisions can be guided by the current literature. Finally we highlight the importance of checking the fit of the imputation model. This process is illustrated using a case study in which we impute missing outcome data in a five-wave longitudinal study that compared extremely preterm individuals with term-born controls.

Evaluation of lung function on impulse oscillometry in preschool children born late preterm.

There is a paucity of data on lung physiology in late-preterm children, who may be exposed to a risk of decline in lung function during childhood. In this study, we evaluated lung function in preschool children born late preterm using impulse oscillometry (IOS), and compared the results with those obtained in healthy term-born children. Children between 3 and 7 years of age who were born late preterm and who were being followed up at the outpatient clinic were included as the late-preterm group. Age-matched healthy term-born children served as controls. A total of 90 late-preterm and 75 healthy children were included in the study. At 5-20 Hz, resistance (R5-R20), reactance (X5-X20), impedans (Z5) and resonant frequency were measured on IOS. Mean IOS R5 and R10 were significantly higher in the late-preterm group than in the control group (P < 0.05). Mean R5, R10 and Z5 were statistically higher in late-preterm children who had been hospitalized for pulmonary infection compared with the control group (P < 0.05). Mean R5, R10, R15, R20 and Z5 were significantly higher, and mean X10 and X15 significantly lower in late-preterm children with passive smoking compared with late-preterm children without passive smoking and controls (P < 0.05). Children born late preterm had signs of peripheral airway obstruction on IOS-based comparison with healthy term-born controls. Besides the inherent disadvantages of premature birth, hospitalization for pulmonary infection and passive smoking also seemed to adversely affect lung function in children born late preterm.

Eating difficulties in children born late and moderately preterm at 2 y of age: a prospective population-based cohort study

Very preterm (<32 wk of gestation) infants are at increased risk of eating difficulties compared with their term-born peers. Little is known about the impact of late and moderately preterm (LMPT; 32-36 wk of gestation) birth on eating difficulties in early childhood. The aims were to assess the prevalence of eating difficulties in infants born LMPT at 2 y corrected age and to explore the impact of neonatal and neurodevelopmental factors. A geographic population-based cohort of 1130 LMPT and 1255 term-born controls was recruited at birth. The parents of 651 (59%) LMPT and 771 (62%) term-born infants completed questionnaires at 2 y corrected age to assess neurodevelopmental outcomes. Parents also completed a validated questionnaire to assess eating behaviors in 4 domains: refusal/picky eating, oral motor problems, oral hypersensitivity, and eating behavior problems. Infants with scores >90th percentile were classified with eating difficulties in each domain. Neonatal data were collected at discharge, and sociodemographic information was collected via maternal interview. Poisson regression was used to assess between-group differences in eating difficulties and to explore associations with neonatal factors and neurodevelopmental outcomes at 2 y of age. In unadjusted analyses, LMPT infants were at increased risk of refusal/picky eating (RR: 1.53; 95% CI: 1.03, 2.25) and oral motor problems (RR: 1.62; 95% CI: 1.06, 2.47). Prolonged nasogastric feeding >2 wk (RR: 1.87; 95% CI: 1.07, 3.25), behavior problems (RR: 2.95; 95% CI: 1.93, 4.52), and delayed social competence (RR: 2.28; 95% CI: 1.49, 3.48) were independently associated with eating difficulties in multivariable analyses. After adjustment for these factors, there was no excess of eating difficulties in LMPT infants. Infants born LMPT are at increased risk of oral motor and picky eating problems at 2 y corrected age. However, these are mediated by other neurobehavioral sequelae in this population. This trial was registered on the UK Clinical Research Network Portfolio at http://public.ukcrn.org.uk/search/ as UKCRN Study ID 7441.

T2 relaxometry in the extremely-preterm brain at adolescence

Survival following very preterm birth is associated with cognitive and behavioral sequelae, which may have identifiable neural correlates. Many survivors of modern neonatal care in the 1990s are now young adults and the evolution of MRI findings into adult life has rarely been evaluated. We have investigated a cohort of 19-year-old adolescents without severe impairments born between 22 and 26weeks of gestation in 1995 (extremely preterm: EP). Using T2 data derived from magnetic resonance imaging we investigate differences between the brains of 46 EP participants (n=46) and the brains of a group of term-born controls (n=20). Despite EP adolescents having significantly reduced gray and white matter volumes, the composition of these tissues, assessed by both single and multi-component relaxometry, appears to be unrelated to either preterm status or gender. This may represent either insensitivity of the imaging technique or reflect that there are only subtle differences between EP subjects and their term-born peers.

Limited microstructural and connectivity deficits despite subcortical volume reductions in school-aged children born preterm with very low birth weight

Preterm birth and very low birth weight (VLBW, ≤1500g) are worldwide problems that burden survivors with lifelong cognitive, psychological, and physical challenges. In this multimodal structural magnetic resonance imaging (MRI) and diffusion MRI (dMRI) study, we investigated differences in subcortical brain volumes and white matter tract properties in children born preterm with VLBW compared to term-born controls (mean age=8years). Subcortical brain structure volumes and cortical thickness estimates were obtained, and fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) were generated for 18 white matter tracts. We also assessed structural relationships between white matter tracts and cortical thickness of the tract endpoints. Compared to controls, the VLBW group had reduced volumes of thalamus, globus pallidus, corpus callosum, cerebral white matter, ventral diencephalon, and brain stem, while the ventricular system was larger in VLBW subjects, after controlling for age, sex, IQ, and estimated total intracranial volume. For the dMRI parameters, group differences were not significant at the whole-tract level, though pointwise analysis found shorter segments affected in forceps minor and left superior longitudinal fasciculus – temporal bundle. IQ did not correlate with subcortical volumes or dMRI measures in the VLBW group. While the deviations in subcortical volumes were substantial, there were few differences in dMRI measures between the two groups, which may reflect the influence of advances in perinatal care on white matter development.

Cortical trajectories during adolescence in preterm born teenagers with very low birthweight

While cross-sectional neuroimaging studies on cortical development predict reductions in cortical volume (surface area and thickness) during adolescence, this is the first study to undertake a longitudinal assessment of cortical surface area changes across the continuous cortical surface during this period. We studied the developmental dynamics of cortical surface area and thickness in adolescents and young adults (aged 15–20) born with very low birth weight (VLBW; <1500 g) as well as in term-born controls. Previous studies have demonstrated brain structural abnormalities in cortical morphology, as well as long-term motor, cognitive and behavioral impairments, in adolescents and young adults with VLBW, but the developmental dynamics throughout adolescence have not been fully explored. T1-weighted MRI scans from 51 VLBW (27 scanned twice) and 79 term-born adolescents (37 scanned twice) were used to reconstruct the cortical surface and produce longitudinal estimates of cortical surface area and cortical thickness. Linear mixed model analyses were performed, and the main effects of time and group, as well as time × group interaction effects, were investigated. In both groups, cortical surface area decreased up to 5% in some regions, and cortical thickness up to 8%, over the five-year period. The most affected regions were located on the lateral aspect of the hemispheres, in posterior temporal, parietal and to some extent frontal regions. There was no significant interaction between time and group for either morphometry variable. In conclusion, cortical thickness decreases from 15 to 20 years of age, in a similar fashion in the clinical and control groups. Moreover, we show for the first time that developmental trajectories of cortical surface area in preterm and term-born adolescents do not diverge during adolescence.

Correlation of central visual function and ROP risk factors in prematures with and without acute ROP at the age of 6–13 years: the Giessen long-term ROP study

AimTo correlate light increment sensitivity (LIS) and visual acuity (VA) with birth weight (BW), gestational age (GA) and stage of acute retinopathy of prematurity (ROP) (STG) in premature children at...

Comparison of cortical folding measures for evaluation of developing human brain

We evaluated 22 measures of cortical folding, 20 derived from local curvature (curvature-based measures) and two based on other features (sulcal depth and gyrification index), for their capacity to distinguish between normal and aberrant cortical development. Cortical surfaces were reconstructed from 12 term-born control and 63 prematurely-born infants. Preterm infants underwent 2–4 MR imaging sessions between 27 and 42weeks postmenstrual age (PMA). Term infants underwent a single MR imaging session during the first postnatal week. Preterm infants were divided into two groups. One group (38 infants) had no/minimal abnormalities on qualitative assessment of conventional MR images. The second group (25 infants) consisted of infants with injury on conventional MRI at term equivalent PMA. For both preterm infant groups, all folding measures increased or decreased monotonically with increasing PMA, but only sulcal depth and gyrification index differentiated preterm infants with brain injury from those without. We also compared scans obtained at term equivalent PMA (36–42weeks) for all three groups. No curvature-based measured distinguished between the groups, whereas sulcal depth distinguished term control from injured preterm infants and gyrification index distinguished all three groups. When incorporating total cerebral volume into the statistical model, sulcal depth no longer distinguished between the groups, though gyrification index distinguished between all three groups and positive shape index distinguished between the term control and uninjured preterm groups. We also analyzed folding measures averaged over brain lobes separately. These results demonstrated similar patterns to those obtained from the whole brain analyses. Overall, though the curvature-based measures changed during this period of rapid cerebral development, they were not sensitive for detecting the differences in folding associated with brain injury and/or preterm birth. In contrast, gyrification index was effective in differentiating these groups.

Early Emergence of Delayed Social Competence in Infants Born Late and Moderately Preterm.

To assess behavioral outcomes and social competence at 2 years of age in infants born late and moderately preterm (LMPT; 32-36 wk gestation). One thousand one hundred and thirty LMPT infants and 1255 term-born (≥37 wk) controls were recruited at birth to a prospective geographical population-based study. Parents completed the Brief Infant and Toddler Social Emotional Assessment (BITSEA) at 2 years corrected age to assess infants' behavior problems and social competence. Cognitive development was assessed using the Parent Report of Children's Abilities-Revised. Parent questionnaires at 2 years were completed for 638 (57%) LMPT and 765 (62%) term-born infants. Group differences in the prevalence of behavior problems and delayed social competence between LMPT infants and term-born controls were adjusted for age, sex, small-for-gestational-age, socioeconomic status and cognitive impairment. Late and moderately preterm infants were at significantly increased risk of delayed social competence compared with term-born controls (26.4% vs. 18.4%; adjusted-relative risk [RR] 1.28; 95% CI, 1.03-1.58), but there was no significant group difference in the prevalence of behavior problems (21.0% vs. 17.6%; adjusted-RR 1.13, 0.89-1.42). Non-white ethnicity (RR 1.68, 1.26-2.24), medium (RR 1.60, 1.14-2.24) and high (RR 1.98, 1.41-2.75) socioeconomic risk and recreational drug use during pregnancy (RR 1.70, 1.03-2.82) were significant independent predictors of delayed social competence in LMPT infants. Birth at 32 to 36 weeks of gestation confers a specific risk for delayed social competence at 2 years of age. This may be indicative of an increased risk for psychiatric disorders later in childhood.

Electroencephalography during general anaesthesia differs between term-born and premature-born children

ObjectivesPremature birth is associated with a wide range of complications in later life, including structural and functional neurological abnormalities and altered pain sensitivity. We investigated whether during anaesthesia premature-born children display different patterns of background EEG activity and exhibit increased responses to nociceptive stimuli. MethodsWe examined background EEG and time-locked responses to clinical cannulation in 45 children (mean age (±SD) at study: 4.9(±3.0)years) under sevoflurane monoanaesthesia maintained at a steady-state end-tidal concentration of 2.5%. 15 were born prematurely (mean gestational age at birth: 29.2±3.9weeks) and 30 were age-matched term-born children. ResultsBackground levels of alpha and beta power were significantly lower in the premature-born children compared to term-born controls (p=0.048). Clinical cannulation evoked a significant increase in delta activity (p=0.032), which was not significantly different between the two groups (p=0.44). ConclusionsThe results indicate that whilst under anaesthesia premature-born children display different patterns of background brain activity compared to term-born children. SignificanceAs electrophysiological techniques are increasingly used by anaesthetists to gauge anaesthetic depth, differences in background levels of electrophysiological brain activity between premature and term-born children may be relevant when considering titration of anaesthetic dose.

Preterm Cognitive Function Into Adulthood.

Very preterm (VP; gestational age <32 weeks) and very low birth weight (VLBW; <1500 g) births are related to impaired cognitive function across the life span. It is not known how stable cognitive functions are from childhood to adulthood for VP/VLBW compared with term-born individuals and how early adult cognitive function can be predicted. The Bavarian Longitudinal Study is a prospective geographically defined cohort study that followed 260 VP/VLBW and 229 term-born individuals from birth to adulthood. Data on cognitive function were assessed with developmental and IQ tests at 5 and 20 months and at 4, 6, 8, and 26 years of age. Across all assessments, VP/VLBW individuals had significantly lower IQ scores than term-born controls, even when individuals with severe cognitive impairment (n = 69) were excluded. IQ scores were found to be more stable over time for VP/VLBW than term-born individuals, yet differences in stability disappeared when individuals with cognitive impairment were excluded. Adult IQ could be predicted with fair certainty (r > 0.50) from age 20 months onward for the whole VP/VLBW sample (n = 260) and from 6 years onward for term-born individuals (n = 229). VP/VLBW individuals more often suffer from cognitive problems across childhood into adulthood and these problems are relatively stable from early childhood onward. VP/VLBW children's risk for cognitive problems can be reliably diagnosed at the age of 20 months. These findings provide strong support for the timing of cognitive follow-up at age 2 years to plan special support services for children with cognitive problems.

White matter abnormalities and impaired attention abilities in children born very preterm

While attention impairments are commonly observed in very preterm (<32weeks' gestational age) children, neuroanatomical correlates of these difficulties are unclear. We aimed to determine whether the microstructural organization of key white matter tracts thought to be involved in attention (cingulum bundle, superior longitudinal fasciculi, reticular activating system, and corpus callosum) were altered in very preterm children compared with term-born controls. We also aimed to determine whether alterations in microstructural organization of these tracts were associated with attention functioning in very preterm children. One hundred and forty-nine very preterm children and 36 term-born controls underwent neuroimaging and assessment of their attention abilities at 7years. Constrained spherical deconvolution and probabilistic tractography was used to identify the key white matter tracts. Altered microstructural organization and reduced tract volume within reticular activating system and corpus callosum were found in the very preterm group compared with the control group. Diffusion and volume changes in the cingulum bundle, superior longitudinal fasciculi, reticular activating system, and corpus callosum were related to variations in attention functioning in the very preterm children. These findings emphasize that white matter tract integrity is associated with later attentional abilities in very preterm children.

Adolescents who were born extremely preterm demonstrate modest decreases in exercise capacity.

We aimed to investigate exercise capacity in adolescents who were born extremely preterm and to study changes through puberty and associations with neonatal data, exercise habits and lung function. This Norwegian population-based controlled cohort study focused on all infants (n = 35) born at a gestational age of ≤ 28 weeks or with a birthweight of ≤ 1000 grams in 1991-1992, together with matched term-born controls. Participants underwent spirometry and a maximal cardiopulmonary treadmill exercise test at 10 and 18 years. At 18 years of age, mean (95% confidence interval) peak oxygen consumption (peak VO2 ) was 42.3 (39.2-45.4) vs 45.3 (41.3-49.3) mL/kg/min in the preterm- and term-born groups, while the completed treadmill distance was 915 (837-992) vs 1017 (912-1122) metres. Peak VO2 was unrelated to neonatal factors and current lung function. Changes between 10 and 18 were similar in the two groups, and positive associations between exercise habits and peak VO2 developed during the period. Exercise capacity was modestly reduced in adolescents born extremely preterm, but the values were considered normal in most participants. Changes during puberty were similar to those observed for term controls, and the findings suggest similar trainability.

Health-related quality of life may deteriorate from adolescence to young adulthood after extremely preterm birth.

This study examined the development of health-related quality of life (HRQoL) and health from adolescence to adulthood after extremely preterm birth. We assessed a population-based cohort of extremely preterm-born (EPB) infants (gestational age of ≤28weeks or birthweight of ≤1000grams) and term-born (TB) controls at 17 and 24years of age. They completed the Child Health Questionnaire-Child Form 87 at 17years of age, the Short Form Health Survey-36 (SF-36) at 24years of age and the Health Behaviour in School-aged Children-Symptom Checklist at both ages. Of the 51 eligible EPB subjects, 46 (90%) were included and nine had severe neurosensory disabilities. On the whole, EPB and TB subjects gave their HRQoL and health similar ratings, but EPB subjects with disabilities reported poorer physical functioning at 17 and EPB subjects without disabilities reported lower scores on three of the eight SF-36 scales for social functioning and mental health and reported more psychological health complaints at 24. Differences remained in adjusted analyses. Changes from 17 to 24years of age were minor in EPB subjects with disabilities. Our comparison of EPB and TB subjects at the ages of 17 and 24 indicated that psychosocial HRQoL may deteriorate for EPB subjects when they enter adulthood.

Subregional Hippocampal Morphology and Psychiatric Outcome in Adolescents Who Were Born Very Preterm and at Term.

BackgroundThe hippocampus has been reported to be structurally and functionally altered as a sequel of very preterm birth (<33 weeks gestation), possibly due its vulnerability to hypoxic–ischemic damage in the neonatal period. We examined hippocampal volumes and subregional morphology in very preterm born individuals in mid- and late adolescence and their association with psychiatric outcome.MethodsStructural brain magnetic resonance images were acquired at two time points (baseline and follow-up) from 65 ex-preterm adolescents (mean age = 15.5 and 19.6 years) and 36 term-born controls (mean age=15.0 and 19.0 years). Hippocampal volumes and subregional morphometric differences were measured from manual tracings and with three-dimensional shape analysis. Psychiatric outcome was assessed with the Rutter Parents’ Scale at baseline, the General Health Questionnaire at follow-up and the Peters Delusional Inventory at both time points.ResultsIn contrast to previous studies we did not find significant difference in the cross-sectional or longitudinal hippocampal volumes between individuals born preterm and controls, despite preterm individual having significantly smaller whole brain volumes. Shape analysis at baseline revealed subregional deformations in 28% of total bilateral hippocampal surface, reflecting atrophy, in ex-preterm individuals compared to controls, and in 22% at follow-up. In ex-preterm individuals, longitudinal changes in hippocampal shape accounted for 11% of the total surface, while in controls they reached 20%. In the whole sample (both groups) larger right hippocampal volume and bilateral anterior surface deformations at baseline were associated with delusional ideation scores at follow-up.ConclusionsThis study suggests a dynamic association between cross-sectional hippocampal volumes, longitudinal changes and surface deformations and psychosis proneness.

Stress in parents of children born very preterm is predicted by child externalising behaviour and parent coping at age 7 years.

To examine factors which predict parenting stress in a longitudinal cohort of children born very preterm, and seen at age 7 years. We recruited 100 very preterm (≤32 weeks gestational age) child-parent dyads and a control group of 50 term-born dyads born between 2001 and 2004 with follow-up at 7 years. Parents completed the Parenting Stress Index, Ways of Coping Questionnaire, Child Behavior Check List, Beck Depression Inventory and the State Trait Anxiety Inventory questionnaires. Child IQ was assessed using the Wechsler Intelligence Scale-IV. After controlling for maternal education, parents of preterm children (95% CI 111.1 to 121.4) scored higher (p=0.027) on the Parenting Stress Index than term-born controls (95% CI 97.8 to 113.2). Regression analyses showed that child externalising behaviour, sex and parent escape/avoidance coping style, predicted higher parenting stress in the preterm group. Parents of preterm girls expressed higher levels of stress than those of boys. Maladaptive coping strategies contribute to greater stress in parents of very preterm children. Our findings suggest that these parents need support for many years after birth of a very preterm infant.

Moderate and late preterm infants exhibit widespread brain white matter microstructure alterations at term-equivalent age relative to term-born controls.

Despite the many studies documenting cerebral white matter microstructural alterations associated with very preterm birth (<32 weeks' gestation), there is a dearth of similar research in moderate and late preterm infants (born 32-36 weeks' gestation), who experience higher rates of neurodevelopmental delays than infants born at term (≥ 37 weeks' gestation). We therefore aimed to determine whether whole brain white matter microstructure differs between moderate and late preterm infants and term-born controls at term-equivalent age, as well as to identify potential perinatal risk factors for white matter microstructural alterations in moderate and late preterm infants. Whole brain white matter microstructure was studied in 193 moderate and late preterm infants and 83 controls at term-equivalent age by performing Tract-Based Spatial Statistics analysis of diffusion tensor imaging data. Moderate and late preterm infants had lower fractional anisotropy and higher mean, axial and radial diffusivities compared with controls in nearly 70% of the brain's major white matter fiber tracts. In the moderate and late preterm group, being born small for gestational age and male sex were associated with lower fractional anisotropy, largely within the optic radiation, corpus callosum and corona radiata. In conclusion, moderate and late preterm infants exhibit widespread brain white matter microstructural alterations compared with controls at term-equivalent age, in patterns consistent with delayed or disrupted white matter microstructural development. These findings may underpin some of the neurodevelopmental delays observed in moderate and late preterm children.

Adult Respiratory Outcomes of Extreme Preterm Birth. A Regional Cohort Study

Lifetime respiratory function after extremely preterm birth (gestational age≤28 wk or birth weight≤1,000 g) is unknown. To compare changes from 18-25 years of age in respiratory health, lung function, and airway responsiveness in young adults born extremely prematurely to that of term-born control subjects. Comprehensive lung function investigations and interviews were conducted in a population-based sample of 25-year-old subjects born extremely prematurely in western Norway in 1982-1985, and in matched term-born control subjects. Comparison was made to similar data collected at 18 years of age. At 25 years of age, 46/51 (90%) eligible subjects born extremely prematurely and 39/46 (85%) control subjects participated. z-Scores for FEV1, forced expiratory flow at 25-75% of vital capacity, and FEV1/FVC were significantly reduced in subjects born extremely prematurely by 1.02, 1.26, and 0.88, respectively, and airway resistance (kPa/L/s) was increased (0.23 versus 0.18). Residual volume to total lung capacity increased with severity of neonatal bronchopulmonary dysplasia. Responsiveness to methacholine (dose-response slope; 3.16 versus 0.85) and bronchial lability index (7.5 versus 4.8%) were increased in subjects born extremely prematurely. Lung function changes from 18 to 25 years and respiratory symptoms were similar in the prematurely born and term-born groups. Lung function in early adult life was in the normal range in the majority of subjects born extremely prematurely, but methacholine responsiveness was more pronounced than in term-born young adults, suggesting a need for ongoing pulmonary monitoring in this population.

Effect of Bronchodilators on Forced Expiratory Volume in 1 s in Preterm-Born Participants Aged 5 and Over: A Systematic Review

Background and Objectives: Preterm-born participants are at risk of long-term deficits in percentage predicted forced expiratory volume in 1 s (%FEV₁). Since it is unclear if these deficits respond to bronchodilators, we systematically reviewed the evidence for reversibility of deficits in %FEV₁ by bronchodilators in preterm-born participants. Design: Studies reporting a change in %FEV₁ in response to bronchodilator treatment in preterm-born participants at ≥5 years of age, with or without a term-born control group, were identified. The quality of studies was assessed by adapted tools. Due to considerable heterogeneity between studies, formal meta-analysis was not possible. Results: From 8,839 titles, 22 studies were identified after an updated search in May 2013. Twenty-one studies assessed the response to a single inhaled dose of a bronchodilator, and 1 study assessed longer-term effects. Most studies observed decreased %FEV₁ in preterm-born participants compared with controls. Most studies observed improved %FEV₁ after a single dose of bronchodilator, with the largest improvements noted in those with bronchopulmonary dysplasia, who had greater deficits of %FEV₁ when compared with preterm and term controls. One long-term study investigated a 2-week terbutaline administration, but the initial FEV₁ after a single dose did not show a change in %FEV₁ of ≥15%, but 5/29 (17%) children had an increased %FEV₁ of ≥10%. Conclusions: In this systematic review, disparate studies were identified. Although single doses of bronchodilators appear to improve the FEV₁ in the short term, further studies are required to assess their longer-term benefits not only on airway obstruction, but also their effect on respiratory symptoms.

Cognitive outcome varies in adolescents born preterm, depending on gestational age, intrauterine growth and neonatal complications

AimThe aim of this study was to investigate long-term cognitive outcome in a cohort of 18-year-olds born preterm and previously assessed at the age of 5.5.MethodsWe tested 134 adolescents born preterm with a very low birthweight of <1500 g and 94 term-born controls with a comprehensive cognitive battery at 18 years of age. The cohort was subdivided into 73 extremely preterm, 42 very preterm and 19 moderately preterm infants with gestational ages of 23–27, 28–31 and 32–36 weeks, respectively. The moderately preterm group was dominated by adolescents born small for gestational age.ResultsVery preterm adolescents performed on a par with term-born controls. In contrast, extremely preterm adolescents displayed inferior results on all cognitive tests, more so if they had suffered neonatal complications. Moderately preterm adolescents scored lower than very preterm and full-term born adolescents, particularly on complex cognitive tasks.ConclusionAdolescents born at 28 weeks of gestation or later, with appropriate birthweight and no perinatal complications, functioned like term-born peers at 18 years of age. Extremely preterm birth per se posed a risk for long-term cognitive deficits, particularly executive deficits. Adolescents born moderately preterm but small for gestational age were at risk of general cognitive deficits.