Cognitive deficit in preschoolers born late-preterm

Late preterm birth and neurocognitive performance in late adulthood: a birth cohort study

OBJECTIVES

We studied if late preterm birth (34 weeks 0 days-36 weeks 6 days of gestation) is associated with performance on the Consortium to Establish a Registry for Alzheimer's Disease Neuropsychological Battery (CERAD-NB) in late adulthood and if maximum attained lifetime education moderated these associations.

METHODS

Participants were 919 Finnish men and women born between 1934 and 1944, who participated in the Helsinki Birth Cohort Study. They underwent the CERAD-NB at a mean age of 68.1 years. Data regarding gestational age (late preterm versus term) were extracted from hospital birth records, and educational attainment data were gathered from Statistics Finland.

RESULTS

After adjustment for major confounders, those born late preterm scored lower on word list recognition (mean difference: -0.33 SD; P = .03) than those born at term. Among those who had attained a basic or upper secondary education, late preterm birth was associated with lower scores on word list recognition, constructional praxis, constructional praxis recall, clock drawing, Mini-Mental State Examination, and memory total and CERAD total 2 compound scores (mean differences: >0.40 SD; P values <.05), and had a 2.70 times higher risk of mild cognitive impairment (Mini-Mental State Examination score: <26 points) (P = .02). Among those with tertiary levels of education, late preterm birth was not associated with CERAD-NB scores.

CONCLUSIONS

Our findings offer new insight into the lifelong consequences of late preterm birth, and they add late preterm birth as a novel risk factor to the list of neurocognitive impairment in late adulthood. Our findings also suggest that attained lifetime education may mitigate aging-related neurocognitive impairment, especially among those born late preterm.

Behavioural outcomes at 3 years of age among late preterm infants admitted to neonatal intensive care: a cohort study

OBJECTIVE

Examine the behavioural outcomes at age 3 years of late preterm infants (LPIs) who were admitted to neonatal intensive care (NIC) in comparison with LPIs who were not admitted.

METHOD

This cohort study prospectively recruited 225 children born late preterm (34-36(+6) weeks gestation) in 2006 in Northern Ireland, now aged 3 years. Two groups were compared: LPIs who received NIC (study; n=103) and LPIs who did not receive NIC (control; n=122). Parents/guardians completed the Child Behaviour Checklist/1½-5. Descriptive maternal and infant data were also collected.

RESULTS

As expected LPI children admitted to NIC had higher medical risk than the non-admitted comparison group (increased caesarean section, born at earlier gestation, lower birth weight and an episode of resuscitation at birth). LPIs admitted to NIC scored higher on the Child Behaviour Checklist/1½-5 compared with those who were not admitted indicating more behavioural problems; this was statistically significant for the Aggressive Behaviour Subscale (z=-2.36) and the Externalising Problems Scale (z=-2.42). The group difference on the Externalising Problems Scale was no longer significant after controlling for gender, gestational age and deprivation score.

CONCLUSIONS

This study provides valuable data on the behaviour at age 3 years of LPIs admitted to NIC compared with LPIs not admitted to NIC. Further research would be beneficial to explore medical and psychosocial explanations for observed differences between groups using large prospective cohort studies.

Predictors of severity and outcome of global developmental delay without definitive etiologic yield: a prospective observational study

BACKGROUND

Although several determinants of global developmental delay (GDD) have been recognized, a significant number of children remain without definitive etiologic diagnosis. The objective of this study was to assess the effect of various prenatal and perinatal factors on the severity and outcome of developmental delay without definitive etiologic yield.

METHODS

From March 2008 to February 2010, 142 children with developmental quotient (DQ) <70 and without definitive etiologic diagnosis, were included. Prenatal and perinatal risk factors known to be associated with disordered neonatal brain function were identified. Participants underwent a thorough investigation, an individualized habilitation plan was recommended, and the children were followed-up regularly for a period of 2 < years. The effect of prenatal and perinatal risk factors on the severity and outcome of GDD was assessed by regression analysis.

RESULTS

The mean age at enrolment was 31 ± 12 < months, and the mean DQ 52.2 ± 11.4. Prematurity and intrauterine growth restriction (IUGR) were found to be independently associated with lower DQ values. The mean DQ after the 2-year follow-up was 62.5 ± 12.7, and the DQ difference from the enrollment 10.4 ± 8.9 (median 10; range-10 to 42). DQ improvement (defined as a DQ difference?≥?median) was noted in 52.8% of the children. IUGR, low socio-economic status, and poor compliance to habilitation plan were found to be independently associated with poorer developmental outcomes.

CONCLUSIONS

Prematurity and IUGR were found to be significantly and independently related to the severity of GDD in cases without definitive etiologic yield. Poorer 2-year developmental outcome was associated with IUGR, low socioeconomic status and non compliance to habilitation plan. Prematurity was a significant determinant of the outcome only in association with the above mentioned factors.

What brakes the preterm brain? An arresting story

Children surviving premature birth have a high risk of cognitive and learning disabilities and attention deficit. In turn, adverse outcomes are associated with persistent reductions in cerebral growth on magnetic resonance imaging (MRI). It is striking that modern care has been associated with a dramatic reduction in the risk of cystic white matter damage, but modest improvements in terms of neurodevelopmental impairment. This review will explore the hypothesis that the disability is primarily associated with impaired neural connectivity rather than cell death alone. Very preterm infants exhibit reduced thalamocortical connectivity and cortical neuroplasticity compared with term-born controls. In preterm fetal sheep, moderate cerebral ischemia with no neuronal loss, but significant diffuse failure of maturation of cortical pyramidal neurons, was associated with impaired dendritic growth and synapse formation, consistent with altered connectivity. These changes were associated with delayed decline in cortical fractional anisotropy (FA) on MRI. Supporting these preclinical findings, preterm human survivors showed similar enduring impairment of microstructural development of the cerebral cortex defined by FA, consistent with delayed formation of neuronal processes. These findings offer the promise that better understanding of impairment of neural connectivity may allow us to promote normal development and growth of the cortex after preterm birth.

Cognitive and psychosocial phenotype of young children with neurofibromatosis-1

Children with neurofibromatosis-1 (NF1), a neurodevelopmental disorder resulting from a mutation of the NF1 gene (17q11.2), often have difficulties with learning and attention, but there is little research in the early childhood years. In this study, the cognitive and psychosocial functioning of 40 young children with NF1 (ages 3 through 6) was examined and compared both to normative data and to a contrast group comprised of unaffected siblings and community members matched for age and socio-economic status (n = 37). Children with NF1 showed significantly weaker cognitive abilities across all domains and for the vast majority of subtests. Consistent with research in older children, a variety of patterns of intra-individual strength and weakness were present for young children with NF1. Few significant group differences in psychosocial functioning were observed, but the children with NF1 showed significantly greater functional communication problems than did the unaffected group. Overall, the results indicate that in participant groups matched for age and socioeconomic status, cognitive vulnerabilities are evident for close to half of young children with NF1, with some relations to psychosocial functioning, particularly functional communication, attention problems and social skills.

Long-term outcomes of moderately preterm, late preterm, and early term infants

At present, moderate preterm (MPT) infants born at 32 to 33 weeks' gestation and late preterm (LPT) infants born at 34 to 36 weeks' gestation make up the largest subgroup of preterm infants and contribute to more than 80% of premature births in the United States. There is increasing evidence that both MPT and LPT infants are at increased risk of neurologic impairments, developmental disabilities, school failure, and behavior and psychiatric problems. Population studies suggest that for each 1 week decrease in gestational age below 39 weeks, there are stepwise increases in adverse outcomes after adjusting for confounders.

In vitro fertilization and late preterm preschoolers' neuropsychological outcomes: the PETIT study

OBJECTIVE

In vitro fertilization (IVF) is considered a generally safe procedure, although associated with a higher incidence of preterm birth. The literature is inconsistent about the psychological impact of IVF, and we found no reports about outcome in late preterm (LPT) children. Our objective was to study neuropsychological and behavioral outcomes in a cohort of preschoolers born LPT between 2004 and 2007.

STUDY DESIGN

Participants were 397 LPT children (mean age, 3.8 years) conceived assisted by IVF (n = 105) or non-IVF (n = 292). Standardized performance-based tests of general conceptual ability (intelligence quotient), executive function, focused/selective attention, visual-spatial perception, visual-motor skill, manual dexterity, learning, and memory were administered. Parents completed behavioral and executive function questionnaires.

RESULTS

IVF group characteristics included older maternal age (P < .001), lower birthweight (P < .001), and higher maternal education (P < .001). No main-effect significant group differences were found for any variable after controlling for these variables. However, sex differences were demonstrated for the neuropsychological variables in copying (P > .001), nonverbal reasoning (P = .001), manual dexterity (P = .001), and inhibitory capacity (P = .006), all favoring girls.

CONCLUSION

Birth following IVF-assisted conception did not increase the risk of intellectual, neuropsychological, or behavioral deficit in LPT preschoolers. As shown in earlier gestational-age participants, girls have selective advantages. These findings should be reassuring for parents who conceive through IVF and deliver infants 1-3 weeks before term gestational age. Future study of these children at elementary school age may detect subtle impairments not yet apparent at age 3 years.

Late-preterm birth and lifetime socioeconomic attainments: the Helsinki birth cohort study

OBJECTIVE

We examined if those born late-preterm (at 34 to 36 weeks of gestation) differed from those born at term in their maximum attained lifetime socioeconomic position (SEP) across the adult years up to 56 to 66 years, and in intergenerational social mobility from childhood parental SEP to own attained SEP.

METHODS

Participants were 8993 Finnish men and women of the Helsinki Birth Cohort Study born between 1934 and 1944. Gestational age was extracted from hospital birth records and socioeconomic attainments from Finnish National Census.

RESULTS

Compared with those born at term, those born late-preterm were more likely to be manual workers, have a basic or upper secondary level of education, belong to the lowest third based on their incomes, and less likely to belong to the highest third based on their incomes. Late-preterm individuals were also less likely to be upwardly mobile and more likely to be downwardly mobile; they were less likely to have higher occupations and more likely to have lower occupations than their fathers. They were also less likely to be upwardly mobile if incomes were used as the outcome of own attained SEP, and men were more likely to be downwardly mobile if education was used as the outcome of own attained SEP.

CONCLUSIONS

This study demonstrates that there are considerable long-term socioeconomic disadvantages associated with late-preterm birth, which are not explained by the parent-of-origin SEP.

Neonatal outcomes are associated with latency after preterm premature rupture of membranes

OBJECTIVE

To determine factors associated with latency time to birth after preterm premature rupture of membranes (PPROM) and the impact on neonatal outcomes.

STUDY DESIGN

Data on singleton pregnancies with PPROM (n=1535 infants) were prospectively collected in a computerized perinatal/neonatal database at a tertiary care perinatal center. Latency was characterized as ≤72h versus >72 h after PPROM.

RESULT

The percentage of women with latency to birth >72 h decreased from 67% in very preterm (gestational age (GA) 25 to 28 weeks) to 10% in late preterm women (GA 33 to 36 weeks). PPROM women with latency ≤72 h were more likely to have pregnancy-induced hypertension and birth weight <3%; PPROM women with latency >72 h were more likely to have received steroids and develop clinical chorioamnionitis. PPROM <32 weeks GA with latency ≤72 h was associated with a two-fold higher incidence of severe neonatal morbidity, while PPROM between 29 to 34 weeks GA and latency ≤72 h was associated with a higher incidence of moderate neonatal morbidity.

CONCLUSION

A latency period >72 h was associated with a decreased incidence of adverse neonatal outcomes up to 32 weeks GA for severe and 34 weeks GA for moderate morbidity indices.

Impact of neonatal intensive care on late preterm infants: developmental outcomes at 3 years

BACKGROUND

Late preterm infants (LPIs) (34-36 weeks' gestation) account for up to 75% of preterm births and constitute a significant proportion of all neonatal admissions. This study assessed the impact of neonatal intensive or high-dependency care (IC) on developmental outcomes of LPIs at 3 years of age.

METHODS

This cohort study included 225 children born late preterm in Northern Ireland during 2006. Children born late preterm who received IC were compared with children born late preterm who did not receive IC. Cognitive, motor, and language skills were assessed by using the Bayley Scales of Infant and Toddler Development, Third Edition. Growth was assessed by using anthropometric measures of height and weight.

RESULTS

LPIs who received IC were more often less mature (34 weeks' gestation), with lower birth weight (≤ 2500 g) and Apgar scores (<7 at 5 minutes) compared with the control group. They were more often born by cesarean delivery and more likely to have received resuscitation at birth. At 3 years of age, children born late preterm who received IC demonstrated similar cognitive, motor, and language skills compared with children in the control group. Measurements of growth also did not differ significantly between groups.

CONCLUSIONS

Despite having increased maternal, perinatal, and neonatal risk factors, there were no significant differences in early childhood development between LPIs who received IC and those who did not. LPIs do not receive routine follow-up after IC and this study provides useful and reassuring data for parents and clinicians on the longer-term outcome of this infant group.

Toward a theory of childhood learning disorders, hyperactivity, and aggression

Learning disorders are often associated with persistent hyperactivity and aggression and are part of a spectrum of neurodevelopmental disorders. A potential clue to understanding these linked phenomena is that physical exercise and passive forms of stimulation are calming, enhance cognitive functions and learning, and are recommended as complementary treatments for these problems. The theory is proposed that hyperactivity and aggression are intense stimulation-seeking behaviors (SSBs) driven by increased brain retinergic activity, and the stimulation thus obtained activates opposing nitrergic systems which inhibit retinergic activity, induce a state of calm, and enhance cognition and learning. In persons with cognitive deficits and associated behavioral disorders, the retinergic system may be chronically overactivated and the nitrergic system chronically underactivated due to environmental exposures occurring pre- and/or postnatally that affect retinoid metabolism or expression. For such individuals, the intensity of stimulation generated by SSB may be insufficient to activate the inhibitory nitrergic system. A multidisciplinary research program is needed to test the model and, in particular, to determine the extent to which applied physical treatments can activate the nitrergic system directly, providing the necessary level of intensity of sensory stimulation to substitute for that obtained in maladaptive and harmful ways by SSB, thereby reducing SSB and enhancing cognitive skills and performance.

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

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

Late preterm birth: a review of medical and neuropsychological childhood outcomes

Late preterm (LP) birth (34 0/7 - 36 6/7 weeks' gestation) accounts for nearly three-fourths of all preterm births, making this population a sizeable public health concern. The immature fetal development associated with LP delivery increases the risk of mortality and short-term medical complications. Which combination of maternal, fetal, or neonatal risk factors may be most critical has only recently begun to be addressed, and whether LP birth's disruptive impact on brain development will exert adverse effects on neuropsychological functioning in childhood and adolescence has been understudied. Early data have shown a graded response, with LP children often functioning better than very preterm children but worse than term children, and with subtle intellectual and neuropsychological deficits in LP children compared with healthy children born at term gestational age. Further characterization of the neuropsychological profile is required and would be best accomplished through prospective longitudinal studies. Moreover, since moderate and LP births result in disparate medical and psychological outcomes, the common methodology of combining these participants into a single research cohort to assess risk and outcome should be reconsidered. The rapidly growing LP outcomes literature reinforces a critical principle: fetal development occurs along a dynamic maturational continuum from conception to birth, with each successive gestational day likely to improve overall outcome.

School outcome, cognitive functioning, and behaviour problems in moderate and late preterm children and adults: a review

A large number of children (6 to 11% of all births) are born at a gestational age between 32 and 36 weeks. Little is known of long term outcomes for these moderate and late preterm children. In this review, results of 28 studies on school outcome, cognitive functioning, behaviour problems, and psychiatric disorders are presented. Overall, more school problems, less advanced cognitive functioning, more behaviour problems, and higher prevalence of psychiatric disorders were found in moderate and late preterm born infants, children, and adults compared with full term peers. Suggestions for future research are discussed.

Late-preterm birth by delivery circumstance and its association with parent-reported attention problems in childhood

OBJECTIVE

Late-preterm birth (LPB, 34-36 wk) has been associated with an increased risk of attention problems in childhood relative to full-term birth (FTB, ≥37 wk), but little is known about factors contributing to this risk. The authors investigated the contributions of clinical circumstances surrounding delivery using follow-up data from the Pregnancy Outcomes and Community Health (POUCH) Study.

METHODS

Women who delivered late preterm or full term and completed the sex- and age-referenced Conners' Parent Rating Scales-Short Form: Revised were included in the present analysis (N = 762; children's age, 3-9 y). The Conners' Parent Rating Scales-Short Form: Revised measures dimensions of behavior linked to attention problems, including oppositionality, inattention, hyperactivity, and a global attention problem index. Using general linear models, the authors evaluated whether LPB subtype (medically indicated [MI] or spontaneous) was associated with these dimensions relative to FTB.

RESULTS

After adjustment for parity, sociodemographics, child age, and maternal symptoms of depression and serious mental illness during pregnancy and at the child survey, only MI LPB was associated with higher hyperactivity and global index scores (mean difference from FTB = 3.8 [95% confidence interval {CI}: 0.5, 7.0] and 3.1 [95% CI 0.0, 6.2]). These findings were largely driven by children between 6 and 9 years. Removal of women with hypertensive disorders during pregnancy (N = 85) or placental findings related to hypertensive conditions (obstruction, decreased maternal spiral artery conversion; N = 134) reduced the differences below significance thresholds.

CONCLUSIONS

Among LPBs, only MI LPB was associated with higher levels of parent-reported childhood attention problems, suggesting that complications motivating medical intervention during the late-preterm period mark increased risk for such problems. Hypertensive disorders seem to play a role in these associations.

Cognitive development in very vs. moderately to late preterm and full-term children: can effortful control account for group differences in toddlerhood?

BACKGROUND

Preterm birth is thought to have an adverse impact on cognitive development and self-regulation.

AIM

Examining the effect of very vs. moderately to late premature birth on cognitive development and effortful control, as well as evaluating whether effortful control explains the link between preterm birth and poorer cognitive development.

SUBJECTS

Fifty-eight very preterm children (<32 weeks gestation or <1500 g birth weight), 88 moderately to late preterm children (≥32 weeks gestation and ≥1500 birth weight) and 86 full-term children (≥38 weeks gestation and ≥2500 g birth weight) were examined at the corrected age of 24 months.

OUTCOME MEASURES

Observational and parent-report measures of effortful control as well as the Bayley Scales of Infant Development II (BSID II, Mental Scale) as a measurement of cognitive development were analyzed.

RESULTS

Very preterm and moderately to late preterm children showed significantly lower cognitive performance compared to full-term children. Lower effortful control scores (on observational measures, but not on parent-reports) were merely found for very preterm children compared to full-term children. Observational measures of effortful control partially mediated the effects of very preterm birth on cognitive performance, but did not explain the effects of moderately to late preterm birth on cognitive performance.

CONCLUSION

Preterm birth in general is related to poorer cognitive performance in toddlerhood. In addition, effortful control mediates the effects of very preterm birth on cognitive development. Findings suggest that different mechanisms link moderately to late premature birth to poor cognitive development.

Long term respiratory outcomes of late preterm-born infants

In recent years, the rate of preterm births has risen in many industrialised countries with late preterm births forming a substantial proportion of the preterm births. Late preterm infants are delivered at the immature saccular stage of lung development when surfactant and antioxidant systems are still developing. It is now increasingly recognised that late preterm infants have increased respiratory morbidity in the neonatal period. In addition, late preterm infants are at an increased risk of lower respiratory tract infections in infancy from respiratory viruses such as respiratory syncytial virus. There is a paucity of data reporting lung function in infancy and childhood in late preterm born children. The available data suggest that children born late preterm may be at risk of decreased lung function in later life. However, further studies are required to assess the medium and long term respiratory consequences of late preterm birth.

Effects of gestational age at birth on health outcomes at 3 and 5 years of age: population based cohort study

OBJECTIVE

To investigate the burden of later disease associated with moderate/late preterm (32-36 weeks) and early term (37-38 weeks) birth.

DESIGN

Secondary analysis of data from the Millennium Cohort Study (MCS).

SETTING

Longitudinal study of infants born in the United Kingdom between 2000 and 2002.

PARTICIPANTS

18,818 infants participated in the MCS. Effects of gestational age at birth on health outcomes at 3 (n = 14,273) and 5 years (n = 14,056) of age were analysed.

MAIN OUTCOME MEASURES

Growth, hospital admissions, longstanding illness/disability, wheezing/asthma, use of prescribed drugs, and parental rating of their children's health.

RESULTS

Measures of general health, hospital admissions, and longstanding illness showed a gradient of increasing risk of poorer outcome with decreasing gestation, suggesting a "dose-response" effect of prematurity. The greatest contribution to disease burden at 3 and 5 years was in children born late/moderate preterm or early term. Population attributable fractions for having at least three hospital admissions between 9 months and 5 years were 5.7% (95% confidence interval 2.0% to 10.0%) for birth at 32-36 weeks and 7.2% (1.4% to 13.6%) for birth at 37-38 weeks, compared with 3.8% (1.3% to 6.5%) for children born very preterm (<32 weeks). Similarly, 2.7% (1.1% to 4.3%), 5.4% (2.4% to 8.6%), and 5.4% (0.7% to 10.5%) of limiting longstanding illness at 5 years were attributed to very preterm birth, moderate/late preterm birth, and early term birth.

CONCLUSIONS

These results suggest that health outcomes of moderate/late preterm and early term babies are worse than those of full term babies. Additional research should quantify how much of the effect is due to maternal/fetal complications rather than prematurity itself. Irrespective of the reason for preterm birth, large numbers of these babies present a greater burden on public health services than very preterm babies.