Fetal growth restriction is not associated with a reduced risk for bilateral spastic cerebral palsy in very-low-birthweight infants

Corticosteroids effect on caspase 3 expression in an in-vitro model of hypoxic brain cells

OBJECTIVE

Effects of corticosteroids (CS) in the brain of growth-restricted fetus remain largely unstudied. We investigated if dexamethasone (DXM) exposure contributes to neuronal injury in an in-vitro model of neuronal cells under hypoxic conditions (surrogate for fetal growth restriction).

STUDY DESIGN

U87 glioblastoma cells exposed to hypoxic or normoxic conditions for 10 h were incubated in the absence or presence of DXM for 48 h. Apoptosis as possible indicator of neurotoxicity was determined using a caspase-3-specific activity assay and western blotting. Caspase-3 was calculated as percentage of mean caspase-3 cleavage. Each experiment was performed in triplicate (n = 48). Caspase 3 activity in cell culture media was also measured by ELISA.

RESULTS

Pro-caspase-3 (32 kDa) was expressed in culture, but activated 17 Kd caspase 3 was not expressed in cell lysate. There was no difference in ratio of caspase 3 activation when U87 cells were exposed to 10 v of hypoxia as compared to normoxia (0.46 ± 0.44 versus 0.37 ± 0.37). The pro-apoptotic effects of DXM were not increased by pre-exposure to hypoxia: (0.37 ± 0.37 versus 0.47 ± 0.40).

CONCLUSION

The addition of DXM to hypoxic U87 cells had no additive or synergistic effects on the activation of caspase 3. Therefore, we speculate that the administration of CS in the setting of fetal growth restriction would not lead to increased apoptosis with potential neuronal injury.

Bronchopulmonary dysplasia and brain white matter damage in the preterm infant: a complex relationship

We analysed the relationship between bronchopulmonary dysplasia (BPD) and brain white matter damage (WMD) in very preterm infants, adjusting for common risk factors and confounders. We studied a cohort of infants <32 weeks gestational age (GA) and <1500 g, admitted to 12 hospitals in Northern Italy in 1999-2002. The association between BPD and WMD was estimated by generalised estimating equations and conditional logistic models, adjusting for centre, GA, propensity score for prolonged ventilation and other potential confounders. Directed acyclic graphs (DAG) were used to depict the underlying causal structure and guide analysis. Of the 1209 infants reaching 36 weeks, 192 (15.8%) developed BPD (supplemental oxygen at 36 weeks) and 88 (7.3%) ultrasound-defined WMD (cystic periventricular leukomalacia). In crude analysis, BPD was a strong risk factor for WMD [odds ratio (OR) = 5.9]. With successive adjustments, the OR progressively decreased to 3.88 when adjusting for GA, to 2.72 adding perinatal risk factors, and further down to 2.16 [95% confidence interval 1.1, 3.9] when ventilation was also adjusted for. Postnatal factors did not change the OR. Significant risk factors for WMD, in addition to BPD, were a low GA, a lower Apgar score, a higher illness severity score, ventilation and early-onset sepsis, while antenatal steroids, being small for GA, and surfactant were associated with a reduced risk. In conclusion, our data suggest that BPD is associated with an increased risk of WMD; most of the effect is due to shared risk factors and causal pathways. DAGs helped clarify the complex confounding of this scenario.

''Intraventricular'' hemorrhage and cystic periventricular leukomalacia in preterm infants: how are they related?

Intraventricular hemorrhage and cystic periventricular leukomalacia are often co-occurring characteristics of brain damage in preterm infants. Using data from 1016 infants born before 30 completed weeks' gestational age, we sought to clarify the relationship between severe intraventricular hemorrhage and cystic periventricular leukomalacia, with special emphasis on common antecedents and potential confounding. After comparing risk factors for intraventricular hemorrhage grades 1 through 4 and cystic periventricular leukomalacia, it appears the risk patterns for intraventricular hemorrhage grade 3, intraventricular hemorrhage grade 4, and cystic periventricular leukomalacia differ. The association between intraventricular hemorrhage grade 3 and cystic periventricular leukomalacia differs appreciably from the association between intraventricular hemorrhage grade 4 and cystic periventricular leukomalacia, supporting the notion that intraventricular hemorrhage grade 3 and intraventricular hemorrhage grade 4 are different entities. The presence of intraventricular hemorrhage grade 3 and intraventricular hemorrhage grade 4 increases the risk of cystic periventricular leukomalacia, even after adjusting for potential confounders. This raises the possibility that intraventricular hemorrhage grade 3 and intraventricular hemorrhage grade 4 cause cystic periventricular leukomalacia.

Neonatal management and long-term sequelae

Intrauterine or fetal growth restriction is best defined by using customised birth weight percentiles based upon the growth potential for an individual infant. Growth restriction in utero may be classified as asymmetric or symmetric depending upon the duration of the process. Asymmetric growth restriction is caused by placental insufficiency, maternal hypertensive conditions, long-standing maternal diabetes, smoking, living at altitude or multiple gestation. Symmetric growth restriction may be due to congenital infections, chromosomal or other abnormalities, fetal alcohol syndrome, low socioeconomic status or be constitutional. The underlying cause of growth restriction often predicts the potential adverse effects on the foetus and newborn and later effects in childhood and adulthood. With placental insufficiency, there may be chronic or acute on chronic fetal hypoxia with birth asphyxia and hypothermia, neonatal hypoglycaemia, polycythaemia and coagulopathy. Management is directed at prevention or early treatment of these conditions. In contrast, symmetrically growth-restricted infants should be examined carefully to look for congenital infections and malformations that may need specific interventions. Infants with constitutional short stature generally do not need any specific management. Feeding of growth-restricted infants is important to overcome deficiencies incurred in utero. Most infants show catch-up growth although about 10% do not. Those with excessive catch-up growth may be at greatest risk of developing insulin resistance in adulthood leading to diabetes, obesity and heart disease. The so-called fetal origins of disease may actually have a postnatal onset related more to excessive weight gain in infancy. There is still controversy over the indications for growth hormone treatment in growth-restricted infants who remain of short stature in early childhood. Intrauterine growth restriction is also associated with a five- to seven-fold increased risk of cerebral palsy probably due to chronic placental insufficiency.

Prediction of neurodevelopmental outcome after preterm birth

Prediction of outcome after preterm birth is critical, but remains difficult, particularly in the early postnatal period. The ability to predict outcome improves parental counseling and selection of infants for early therapeutic strategies aiming at preventing or ameliorating cerebral injury. This review gives an overview of the spectrum and severity of neurodevelopmental, behavioral, and psychosocial outcomes, with discussion of predictors of outcome and, in particular, the clinical, electrophysiological, and imaging predictors. A detailed neurologic examination of infants is a valuable predictive tool in terms of later moderate to severe neurodevelopmental impairments; however, it may be limited in the immediate newborn period. Electrophysiological, neuroimaging, and clinical risk factors for adverse neurodevelopmental outcome have been identified. Good prediction is usually achieved for major functional disabilities in early childhood, but is poorer for moderate or mild long-term outcome. Future research should focus on the long-term quality of life, academic achievement, and the influence of the sociocultural environment. More emphasis should be placed on genetic diversity as a modifying factor for the large variability in outcome.

Cerebral palsy and restricted growth status at birth: population-based case-control study

OBJECTIVE

To evaluate the association between growth status at birth and subsequent development of cerebral palsy in preterm and term infants.

DESIGN

Population-based case-controlled study.

SETTING

Cerebral palsy register in Western Sweden. Subjects Cohort of 334 singletons born between 1983 and 1990, with cerebral palsy diagnosed from age 4, and 668 singletons matched for gestation, gender and delivery unit.

METHOD

Growth status at birth was determined using small for gestational age (SGA) categories, with customised birthweight percentiles (SGAcust) based on the Swedish population.

MAIN OUTCOME MEASURES

Proportion of babies that were SGAcust, comparing cases and controls in three gestational age categories: early preterm (24-33 weeks), late preterm (34-36 weeks) and term (37+ weeks).

RESULTS

Of the 334 children with cerebral palsy, 87 (26.6%) were born early preterm, 27 (8.1%) late preterm and 218 (66%) at term. Children who had been born at term were more likely to have been SGA <1st customised percentile (SGAcust1) than their matched controls (OR 6.6, 95% CI 2.3-18.6). In contrast, children with cerebral palsy born preterm were not more likely to have been SGAcust1 (OR 0.9, 95% CI 0.4-1.9), and this applied to early preterm as well as late preterm births. For less severely small babies (SGA between 1st and 5th customised percentiles), the association with cerebral palsy remained significant for term births (OR 5.2, 95% CI 2.7-10.1) but was again not significant for preterm births.

CONCLUSIONS

Term singletons with severely SGA birthweights had a five- to seven-fold risk of developing cerebral palsy compared with gestational age-matched infants with birthweights within normal limits. For children born preterm, SGA was not more likely to be present in cases than in controls. These findings support the concept of cerebral palsy as a multifactorial condition and highlight the importance of antenatal surveillance of fetal growth.

Neuroprotective role of minocycline in co-cultures of human fetal neurons and microglia

Bacterial infections during pregnancy often result in premature birth and neonatal white matter damage. During these infections, microglia, the resident immune cells of the CNS, undergo activation and contribute to further neuronal damage of the CNS. Minocycline, a second-generation tetracycline antibiotic, inhibits microglial activation and protects neurons in rodents but data about its effects on human cells are limited. We studied the mechanism of the neuroprotective effect of minocycline in either purified cell cultures or co-cultures of microglia and neurons from human fetal brain during inflammation induced by lipopolysaccharide (LPS). In neuron/microglial co-cultures, minocycline treatment prevented activation and proliferation of microglia and protected neurons as demonstrated by decreased neuronal cell death and a shift of Bcl-2 family proteins toward anti-apoptotic ratio. Notably, neither minocycline nor LPS had an effect on neurons in purified neuronal cultures. The ability of minocycline to regulate activation of human fetal microglia might be relevant in therapies used towards treating neonatal CNS infections.

Population based study on the outcome of small for gestational age newborns

OBJECTIVE

To explore whether and how population based data from a regional quality control programme can be used to investigate the hypothesis that small for gestational age (SGA) very low birthweight infants (VLBW, <1500 g) are at increased risk of death, severe intraventricular haemorrhage (IVH), and periventricular leucomalacia (PVL), but at decreased risk of respiratory distress syndrome (RDS).

METHODS

Analyses of population based perinatal/neonatal data (1991-96) from a quality control programme in Lower Saxony, Germany. After assessment of data validity and representativeness, exclusion criteria were defined: birth weight >90th centile, severe malformations, siblings of multiple births, and gestational age (GA) <25 or >29 weeks. Outcomes of interest were death, severe IVH, PVL, and RDS. Multivariable analyses were performed by Cox proportional hazard and logistic regression models.

RESULTS

Within the data validation procedure, an increase in proportions of both VLBW (from 0.95% in 1991 to 1.11% in 1996; +17%) and SGA (from 22.7% to 27.4%; +21%) infants became apparent (p<0.05). The study population consisted of 1623 infants (173 SGA). Mortality was 12.1% (n = 196), with an adjusted hazard ratio for SGA infants of 2.54, 95% confidence interval (CI) 1.70 to 3.79. Both groups were at similar risk of severe IVH (adjusted odds ratio 0.93, 95% CI 0.5 to 1.65) and PVL (1.54, 95% CI 0.78 to 2.87), but SGA infants had less RDS (0.57, 95% CI 0.35 to 0.93). Male sex, multiple birth, hypothermia (<35.5 degrees C), and sepsis were associated with IVH and RDS. Infants admitted to hospitals with <36 VLBW admissions/year had increased mortality (adjusted hazard ratio 1.56, 95% CI 1.12 to 2.18).

CONCLUSIONS

SGA VLBW infants are at increased risk of death, but not of IVH and PVL, and at decreased risk of RDS. That mortality is higher in smaller hospitals needs further investigation.

Impact of motor skills on cognitive test results in very-low-birthweight children

Standardized tests that are frequently used to evaluate the cognitive development of very-low-birthweight children often appear to measure motor ability as well as cognitive skills. To estimate the impact of motor skills on individual test performance among very-low-birthweight children of kindergarten age, we employed factor analysis in a sample of 298 very-low-birthweight children that included severely disabled children. Using a test battery designed to measure concentration, language skills, overall cognitive development, visuomotor abilities, and memory, we identified two factors in each of three diagnostic subgroups: unimpaired children (n = 184), clumsy children (n = 56), and children with cerebral palsy (n = 33). Based on the pattern of factor loadings, we interpret the first factor as capturing language and overall cognitive abilities, whereas the second factor appears to capture motor abilities. Language skills explained 49% and motor abilities accounted for 16% of the overall variance of the individual test results. Among children with attention deficit (n = 25), a third factor emerged. In these children, we interpret the first factor as capturing language or cognitive skills, the second as representing visuomotor skills, and the third as a quantifier of the ability to concentrate. The test battery tested the same abilities in impaired and unimpaired children; however, these were not always the abilities that the battery aimed to test. Future studies need to evaluate whether factor scores only for cognitive but not motor abilities might be useful outcome variables.

Postnatal growth in VLBW infants: significant association with neurodevelopmental outcome

OBJECTIVE

To study the significance of growth status at birth and postnatal growth on neurodevelopmental outcome in very low birth weight (VLBW) infants.

STUDY DESIGN

Growth and neurodevelopment were examined in 219 VLBW (<1250 g) children, 94 small for gestational age (SGA) (<10th percentile) and 125 appropriate for gestational age (AGA) (>10th percentile). Outcome at age 2 was assessed with the Bayley Scales of Infant Development (Mental Developmental Index [MDI], Psychomotor Developmental Index [PDI]) and a standardized neurologic examination.

RESULTS

SGA status was not associated with poor neurodevelopmental outcome. However, after adjustment for covariables including cerebral palsy (CP), SGA children with weight <10th percentile at age 2 had lower mean PDI than SGA children with catch-up growth to weight >10th percentile (mean [SD], 89.9 [17.4] versus 101.8 [14.5]; P<.001). AGA children with catch-down growth (weight <10th percentile at age 2) were, independent of CP, more likely to have lower mean MDI (94.9 vs 101.7, P=.05) and PDI (81.9 vs 95.1; P<.001) than AGA children remaining >10th percentile at age 2. They also more frequently had severe CP (22.9% vs 1.2%; P=.008).

CONCLUSIONS

In VLBW children, the course of postnatal growth rather than the appropriateness of weight for gestational age at birth determines later neurodevelopmental outcome.

Intersite differences in weight growth velocity of extremely premature infants

OBJECTIVE

To explain differences in weight growth velocity of extremely premature infants among 6 level III neonatal intensive care units (NICUs).

METHODS

In 6 NICUs, we studied 564 infants, stratified by gestational age (GA), who were first admissions, survivors, <30 weeks' GA at birth, and in the NICU at least 16 days. Case mix (eg, birth weight, GA, race, illness severity, prenatal steroids), exposure to medical practices/complications (eg, respiratory support, postnatal steroids, necrotizing enterocolitis, infection), and nutritional intake (kcal/kg/d and protein in g/kg/d) were collected and used to predict weight growth velocity between day 3 and day 28 (or discharge, if transferred early) in multiple linear regression models.

RESULTS

Weight growth velocities varied significantly among the 6 NICUs. Adjustment for case mix and medical factors explained little of this variability, but additional control for calorie and especially protein intake accounted for much of the intersite variability. For the average infant, adjusted growth velocity ranged from 10.4 to 14.3 g/kg/d among the sites studied. The final predictive model, including case mix and medical and nutritional factors, explained 53% of the overall variance in growth velocity. Prolonged (> or =15 days) exposure to postnatal steroids and greater severity of illness both decreased growth velocity. The model predicted that adding 1 g/kg/d protein to the mean intake for our sample would increase growth by 4.1 g/kg/d.

CONCLUSIONS

Variation in nutrition explained much of the difference in growth among the NICUs studied. Mean intake of calories and protein failed to meet recommended levels, and the average growth in only 1 NICU approximated intrauterine growth standards. Increasing nutritional intake into the recommended ranges, in particular of protein, may increase growth of extremely premature infants up to or above intrauterine rates.