Nynke Weisglas-Kuperus

Meta-analysis of neurobehavioral outcomes in very preterm and/or very low birth weight children

OBJECTIVE: Sequelae of academic underachievement, behavioral problems, and poor executive function (EF) have been extensively reported for very preterm (≤33 weeks gestation) and/or very low birth weight (VLBW) (≤1500 g) children. Great variability in the published results, however, hinders the field in studying underlying dysfunctions and developing intervention strategies. We conducted a quantitative meta-analysis of studies published between 1998 and 2008 on academic achievement, behavioral functioning, and EF with the aim of providing aggregated measures of effect size for these outcome domains. METHODS: Suitable for inclusion were 14 studies on academic achievement, 9 studies on behavioral problems, and 12 studies on EF, which compared a total of 4125 very preterm and/or VLBW children with 3197 term-born controls. Combined effect sizes for the 3 outcome domains were calculated in terms of Cohens d. Q-test statistics were performed to test homogeneity among the obtained effect sizes. Pearsons correlation coefficients were calculated to examine the impact of mean birth weight and mean gestational age, as well as the influence of mean age at assessment on the effect sizes for academic achievement, behavioral problems, and EF. RESULTS: Combined effect sizes show that very preterm and/or VLBW children score 0.60 SD lower on mathematics tests, 0.48 SD on reading tests, and 0.76 SD on spelling tests than term-born peers. Of all behavioral problems stacked, attention problems were most pronounced in very preterm and/or VLBW children, with teacher and parent ratings being 0.43 to 0.59 SD higher than for controls, respectively. Combined effect sizes for parent and teacher ratings of internalizing behavior problems were small (<0.28) and for externalizing behavior problems negligible (<0.09) and not significant. Combined effect sizes for EF revealed a decrement of 0.57 SD for verbal fluency, 0.36 SD for working memory, and 0.49 SD for cognitive flexibility in comparison to controls. Mean age at assessment was not correlated with the strength of the effect sizes. Mathematics and reading performance, parent ratings of internalizing problems, teacher ratings of externalizing behavior, and attention problems, showed strong and positive correlations with mean birth weight and mean gestational age (all r values > 0.51). CONCLUSIONS: Very preterm and/or VLBW children have moderate-to-severe deficits in academic achievement, attention problems, and internalizing behavioral problems and poor EF, which are adverse outcomes that were strongly correlated to their immaturity at birth. During transition to young adulthood these children continue to lag behind term-born peers.

Functional aspects of developmental toxicity of polyhalogenated aromatic hydrocarbons in experimental animals and human infants

A scientific evaluation was made of functional aspects of developmental toxicity of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in experimental animals and in human infants. Persistent neurobehavioral, reproductive and endocrine alterations were observed in experimental animals, following in utero and lactational exposure to PCBs, PCDDs and PCDFs. The lowest observable adverse effect levels (LOAELs) for developmental neurobehavioral and reproduction endpoints, based on body burden of TCDD-toxic equivalents (TEQs) in animals, are within the range of current background human body burdens. Relatively subtle adverse effects on neurobehavioral development and thyroid hormone alterations have also been observed in infants and children exposed to background levels. Exclusive use of the toxic equivalency factor (TEF) approach may underestimate the risk of neurodevelopmental effects, because both Ah receptor dependent and independent mechanisms may be involved in these effects. The use of marker congeners and/or bioassays based on Ah receptor mediated mechanisms are rapid, low cost pre-screening alternatives for expensive and time consuming gas chromatographic-mass spectrometric analysis.

Functional outcomes and participation in young adulthood for very preterm and very low birth weight infants: the Dutch Project on Preterm and Small for Gestational Age Infants at 19 years of age.

OBJECTIVE. Young adults who were born very preterm or with a very low birth weight remain at risk for physical and neurodevelopmental problems and lower academic achievement scores. Data, however, are scarce, hospital based, mostly done in small populations, and need additional confirmation. METHODS. Infants who were born at <32 weeks of gestation and/or with a birth weight of <1500 g in the Netherlands in 1983 (Project on Preterm and Small for Gestational Age Infants) were reexamined at age 19. Outcomes were adjusted for nonrespondents using multiple imputation and categorized into none, mild, moderate, or severe problems. RESULTS. Of 959 surviving young adults, 74% were assessed and/or completed the questionnaires. Moderate or severe problems were present in 4.3% for cognition, 1.8% for hearing, 1.9% for vision, and 8.1% for neuromotor functioning. Using the Health Utility Index and the London Handicap Scale, we found 2.0% and 4.5%, respectively, of the young adults to have ≥3 affected areas in activities and participation. Special education or lesser level was completed by 24%, and 7.6% neither had a paid job nor followed any education. Overall, 31.7% had ≥1 moderate or severe problems in the assessed areas. CONCLUSIONS. A total of 12.6% of young adults who were born very preterm and/or with a very low birth weight had moderate or severe problems in cognitive or neurosensory functioning. Compared with the general Dutch population, twice as many young adults who were born very preterm and/or with a very low birth weight were poorly educated, and 3 times as many were neither employed nor in school at age 19.

Intelligence of very preterm or very low birthweight infants in young adulthood

Objective: To examine the effect of intrauterine and neonatal growth, prematurity and personal and environmental risk factors on intelligence in adulthood in survivors of the early neonatal intensive care era. Methods: A large geographically based cohort comprised 94% of all babies born alive in the Netherlands in 1983 with a gestational age below 32 weeks and/or a birth weight >1500 g (POPS study). Intelligence was assessed in 596 participants at 19 years of age. Intrauterine and neonatal growth were assessed at birth and 3 months of corrected age. Environmental and personal risk factors were maternal age, education of the parent, sex and origin. Results: The mean (SD) IQ of the cohort was 97.8 (15.6). In multiple regression analysis, participants with highly educated parents had a 14.2-point higher IQ than those with less well-educated parents. A 1 SD increase in birth weight was associated with a 2.6-point higher IQ, and a 1-week increase in gestational age was associated with a 1.3-point higher IQ. Participants born to young mothers (<25 years) had a 2.7-point lower IQ, and men had a 2.1-point higher IQ than women. The effect on intelligence after early (symmetric) intrauterine growth retardation was more pronounced than after later (asymmetric) intrauterine or neonatal growth retardation. These differences in mean IQ remained when participants with overt handicaps were excluded. Conclusions: Prematurity as well as the timing of growth retardation are important for later intelligence. Parental education, however, best predicted later intelligence in very preterm or very low birthweight infants.

Effects of perinatal exposure to PCBs on neuropsychological functions in the Rotterdam cohort at 9 years of age.

PCBs are known for their neurotoxic properties, especially on the developing brain. To increase insight into the neurotoxic effects of PCB exposure, the authors studied the effects of perinatal exposure to environmental levels of these compounds on different neuropsychological domains. In 9-year-old children of the Rotterdam PCB--dioxin cohort, higher prenatal PCB levels were associated with longer response times (RTs), more variation in RTs, and lower scores on the Tower of London (TOL; Shallice, 1982). A longer breast-feeding duration was associated with lower TOL scores and with better spatial organizational skills. There was some evidence of negative effects of lactational exposure to PCBs on scores on the TOL.

BEHAVIOUR PROBLEMS OF VERY LOWBIRTHWEIGHT CHILDREN

Parent and clinician reports of behaviour problems among very low‐birthweight (VLBW) children at 3½ years of age were studied in relation to indicators of neonatal cerebral damage, cognition and social factors. VLBW children had more depressed behaviour and more internalizing problems by parent report, and also scored significantly more often within the clinical range on total problem scores, than children in the comparison group. Neither neonatal cerebral ultrasound nor neurological examinations were directly associated with behavioural outcome. Cerebral damage was related to cognitive development. Cognition directly influenced behaviour problems according to clinician report, while the home environment did so according to parent report. The authors suggest that depressed behaviour of preschool VLBW children might be associated with parental reactions to the birth of a VLBW child, and that their attention problems might be linked indirectly to brain damage via cognitive impairments.

Long-term neurodevelopmental outcome of monochorionic and matched dichorionic twins

Background Monochorionic (MC) twins are at increased risk for perinatal mortality and serious morbidity due to the presence of placental vascular anastomoses. Cerebral injury can be secondary to haemodynamic and hematological disorders during pregnancy (especially twin-to-twin transfusion syndrome (TTTS) or intrauterine co-twin death) or from postnatal injury associated with prematurity and low birth weight, common complications in twin pregnancies. We investigated neurodevelopmental outcome in MC and dichorionic (DC) twins at the age of two years. Methods This was a prospective cohort study. Cerebral palsy (CP) was studied in 182 MC infants and 189 DC infants matched for weight and age at delivery, gender, ethnicity of the mother and study center. After losses to follow-up, 282 of the 366 infants without CP were available to be tested with the Griffiths Mental Developmental Scales at 22 months corrected age, all born between January 2005 and January 2006 in nine perinatal centers in The Netherlands. Due to phenotypic (un)alikeness in mono-or dizygosity, the principal investigator was not blinded to chorionic status; perinatal outcome, with exception of co-twin death, was not known to the examiner. Findings Four out of 182 MC infants had CP (2.2%) - two of the four CP-cases were due to complications specific to MC twin pregnancies (TTTS and co-twin death) and the other two cases of CP were the result of cystic PVL after preterm birth - compared to one sibling of a DC twin (0.5%; OR 4.2, 95% CI 0.5–38.2) of unknown origin. Follow-up rate of neurodevelopmental outcome by Griffiths test was 76%. The majority of 2-year-old twins had normal developmental status. There were no significant differences between MC and DC twins. One MC infant (0.7%) had a developmental delay compared to 6 DC infants (4.2%; OR 0.2, 95% 0.0–1.4). Birth weight discordancy did not influence long-term outcome, though the smaller twin had slightly lower developmental scores than its larger co-twin. Conclusions There were no significant differences in occurrence of cerebral palsy as well as neurodevelopmental outcome between MC and DC twins. Outcome of MC twins seems favourable in the absence of TTTS or co-twin death.

Executive Function and IQ Predict Mathematical and Attention Problems in Very Preterm Children

Objective of this study was to examine the impact of executive function (EF) on mathematical and attention problems in very preterm (gestational age ≤ 30 weeks) children. Participants were 200 very preterm (mean age 8.2 ± 2.5 years) and 230 term children (mean age 8.3 ± 2.3 years) without severe disabilities, born between 1996 and 2004. EFs assessed included verbal fluency, verbal working memory, visuospatial span, planning, and impulse control. Mathematics was assessed with the Dutch Pupil Monitoring System and parents and teachers rated attention problems using standardized behavior questionnaires. The impact of EF was calculated over and above processing speed indices and IQ. Interactions with group (very preterm versus term birth status) were examined. Analyses were conducted separately for two subsamples: children in preschool and children in primary school. Very preterm children performed poorer on tests for mathematics and had more parent and teacher rated attention problems than term controls (ßs>.11, Ps<.01). IQ contributed unique variance to mathematics in preschool and in primary school (ßs>.16, Ps<.007). A significant interaction of group with IQ (ßu200a=u200a−. 24, Pu200a=u200a.02) showed that IQ contributed unique variance to attention problems as rated by teachers, but that effects were stronger for very preterm than for term infants. Over and above IQ, EF contributed unique variance to mathematics in primary school (ßu200a=u200a.13, P<.001), to parent rated inattention in preschool and in primary school (ßs>−.16, Ps<.04), and to teacher rated inattention in primary school (ßu200a=u200a−.19; ßu200a=u200a.19, Ps<.009). In conclusion, impaired EF is, over and above impaired IQ, an important predictor for poor mathematics and attention problems following very preterm birth.

Cognitive outcome of patients with classic infantile Pompe disease receiving enzyme therapy

Objective: Classic infantile Pompe disease affects many tissues, including the brain. Untreated infants die within their first year. Although enzyme-replacement therapy (ERT) significantly increases survival, its potential limitation is that the drug cannot cross the blood-brain barrier. We therefore investigated long-term cognitive development in patients treated with ERT. Methods: We prospectively assessed cognitive functioning in 10 children with classic infantile Pompe disease who had been treated with ERT since 1999. Brain imaging was performed in 6 children. Results: During the first 4 years of life, developmental scores in 10 children ranged from above-average development to severe developmental delay; they were influenced by the type of intelligence test used, severity of motor problems, speech/language difficulties, and age at start of therapy. Five of the children were also tested from 5 years onward. Among them were 2 tetraplegic children whose earlier scores had indicated severe developmental delay. These scores now ranged between normal and mild developmental delay and indicated that at young age poor motor functioning may interfere with proper assessment of cognition. We found delayed processing speed in 2 children. Brain imaging revealed periventricular white matter abnormalities in 4 children. Conclusions: Cognitive development at school age ranged between normal and mildly delayed in our long-term survivors with classic infantile Pompe disease treated with ERT. The oldest was 12 years. We found that cognition is easily underestimated in children younger than 5 years with poor motor functioning.

Implementation of a nation-wide automated auditory brainstem response hearing screening programme in neonatal intensive care units

Aim: As part of a future national neonatal hearing screening programme in the Netherlands, automated auditory brainstem response (AABR) hearing screening was implemented in seven neonatal intensive care units (NICUs). The objective was to evaluate key outcomes of this programme: participation rate, first stage success rate, pass/referral rates, rescreening compliance, diagnostic referral rates, age of first diagnostic evaluation and prevalence of congenital hearing loss (CHL). Methods: This prospective cohort study collected data on 2513 survivors. NICU graduates with one or more risk factors according to the Joint Committee on Infant Hearing were included in a two‐stage AABR hearing screening programme. Conventional ABR was used to establish a diagnosis of CHL. Results: A total of 2513 newborns enrolled in the programme with a median gestational age of 31.6 (range 24–43) wk and a median birthweight of 1450 (range 510–4820) g. In 25 (1%) cases parents refused screening. Four out of 2513 newborns were initially lost; 2484 newborns have been tested initially. A final 98% participation rate (2465/2513) was obtained for the whole programme. After a median postmenstrual age at the first test of 33.7 (range 27–54) wk, a pass rate of 2284/2484 (92%) resulted at the first stage. The rescreening compliance after the first test was 92% (184/200). A referral rate for diagnostic ABR of 3.1% (77/2484) resulted. Of the 77 referrals 14 (18.2%) had normal screening thresholds, 15 (19.5%) had unilateral CHL and 48 (62.3%) had bilateral CHL. The prevalence of unilateral CHL was 0.6% (15/2484) and of bilateral CHL 1.9% (48/2484).