Cerebral palsy and perinatal care

Reduced fetal movements and maternal medication - new pregnancy risk factors for neurodevelopmental disability in childhood

A case-control study was undertaken of 471 children on the Nottingham Special Needs Register (SNR) who were born in one of the two maternity units in the city between 1987 and 1993 (inclusive). Controls were selected as the next infant born at the same hospital following each index case. The aim of the study was to identify risk factors on the Nottingham Obstetric Database for a baby subsequently appearing on the SNR. Disability was analysed by both ICD-9 coding and functional assessment. Factors which independently and significantly predicted a child's likelihood of being on the SNR were breech presentation (adjusted odds ratio (OR) = 4.0), congenital abnormality (OR=4.9), intrapartum fetal distress (OR=1.7), fetal growth restriction (OR=2.0), socioeconomic deprivation (OR=1.8), prematurity (OR=2.2), reduced fetal movements (OR=2.5) and medication in pregnancy (OR=10.4). To our knowledge the last two factors have not previously been reported as risk predictors for neurodevelopmental disability.

The CTG and the timing and mechanism of fetal neurological injuries

Defining the relationship between the cardiotocograph (CTG) pattern and subsequent neurological injury is confounded by the requirement that certain clinical and biochemical perinatal findings are essential for relating intrapartum events to subsequent neurological injury. Similarly, the value of CTG analysis in these cases has been compromised by antiquated terminology focused on hypoxia but not neurological behavior. Strong evidence suggests that the evaluation of umbilical artery acidosis, low Apgar score and neonatal encephalopathy are limited in their ability to either include or exclude intrapartum injury. Proper evaluation of the CTG requires that trends and the rapidity of changes in patterns of decelerations are necessary to confidently define the normal-behaving fetus, the hypoxemic but uninjured fetus, the injured but non-hypoxic fetus, and finally to distinguish ischemic events from other forms of hypoxia. A newly defined CTG pattern, the 'conversion' pattern, appears to be a specific marker of ischemic injury and could help to redefine the role of CTG monitoring.

Temporal and demographic trends in cerebral palsy--fact and fiction

The rate of cerebral palsy has not decreased in developed countries over the past 30 years, despite the widespread use of electronic fetal heart rate monitoring and a 5-fold increase in the cesarean delivery rate over the same period of time. However, neonatal survival has improved during these decades. These observations have lead to the hypothesis that increased survival of premature, neurologically impaired infants may have masked an actual reduction in cerebral palsy among term infants as a result of the use of electronic monitoring and the avoidance of intrapartum asphyxia. A review of the medical literature, as well as a demographic analysis of term and preterm birth rates in the United States, refutes this hypothesis on four grounds. First, cerebral palsy prevalence has been separately analyzed in term infants and shows no change over 30 years. Second, the prevalence of cerebral palsy is the same or lower in underdeveloped countries than in developed nations; in the former, the availability of emergency cesarean delivery based on electronic monitor data is limited or absent. Third, the increase in prevalence of cerebral palsy among low-birth-weight infants and the increase in cesarean sections based on presumed fetal distress were not simultaneous events-the former preceded the latter by a decade. Improved neonatal survival since the 1980s has been associated with a stable or decreasing rate of neurologic impairment and thus could not have obscured improvement from reduced term asphyxia. Finally, compared with the number of infants born by cesarean section for fetal distress, there are simply not enough infants born in the most vulnerable weight groups to make any impact on even a minimal improvement of outcome in the group delivered by cesarean section for presumed fetal distress. Except in rare instances, cerebral palsy is a developmental event that is unpreventable given our current state of technology.

The relationship between placental and other perinatal risk factors for neurologic impairment in very low birth weight children

Placental abnormalities reflect antenatal disease processes that may interact with other perinatal risk factors to affect long-term outcome. We performed a nested case control analysis of placental and clinical risk factors associated with neurologic impairment (NI) at 20-mo corrected age (60 cases and 59 controls) using data collected in a prospective study of very low birth weight (less than 1500 g) infants born between 1983 and 1991. In a preliminary analysis we explored the relationship between clinical infection and histologic chorioamnionitis (CA). Only histologic CA with a fetal vascular response correlated with either clinical CA or early onset neonatal sepsis. We then assessed the relative contribution of the nine risk factors (four placental and five clinical) associated with NI at the univariate level by multiple logistic regression. Three risk factors were independent predictors of NI: severe cranial ultrasound abnormalities (odds ratio 13.6, 95% confidence intervals 4.5-66.7), multiple placental lesions (odds ratio 13.2, 95% confidence intervals 1.3-137.0), and oxygen dependence at 36 wk (odds ratio 4.2, 95% confidence intervals 1.2-14.6). Finally, a series of logistic regressions was conducted with the dependent variable changing as we moved back along the causal chain to explore the relationships between risk factors operating at different stages. This analysis suggested that antenatal variables that were not independent predictors of NI by multiple logistic regression exerted their effects through the following intermediate pathways: fetal grade 3 histologic CA via chorionic vessel thrombi, clinical CA via grade 3 villous edema, and grade 3 villous edema via severe cranial ultrasound abnormalities.

Antenatal and delivery risk factors simultaneously associated with neonatal death and cerebral palsy in preterm infants

To evaluate the simultaneous effects of antenatal and delivery risk factors on neonatal death and cerebral palsy in preterm infants, we conducted a cohort study of 363 singleton pregnancies delivered between 24 and 33 weeks gestation. Neurodevelopmental outcome of the infants was evaluated at 2 years of corrected age. Risk factors associated with death or cerebral palsy were analysed by politomous logistic regression. Overall, the mortality rate was 14.6% (53/363) and the prevalence of cerebral palsy among surviving infants was 12.3% (38/310). Decreasing gestation and meconium-stained amniotic fluid were the only antenatal factors associated with increased odds for both death and cerebral palsy. The effect magnitude and the predictive value of gestational age were greater for death than for cerebral palsy. After adjustment for confounders, prolonged (> or = 48 h) rupture of membranes (odds ratio 2.98, 95% confidence interval 1.12-7.96) and male sex of the infant (odds ratio 3.01, 95% confidence interval 1.32-6.71) were significantly associated only with cerebral palsy. We conclude that neonatal death and cerebral palsy share few common antenatal risk factors. The characteristics of antenatal risk factors for cerebral palsy suggest that bacterial infestation of the amniotic cavity may be implicated in the etiology of the cerebral impairment.