Does continuous intrapartum fetal monitoring predict long-term neurological disorders?

Obstetric approaches to the prevention of meconium aspiration syndrome

Meconium aspiration syndrome (MAS) is associated with increased risk for perinatal mortality and morbidities. To provide an overview of the advances in our knowledge concerning the obstetric approaches to the prevention of MAS. The evidence of the effectiveness of intrapartum surveillance, amnioinfusion, and delivery room management in the prevention of MAS are reviewed in the present paper. Meconium aspiration syndrome remains one of the most common but challenging conditions for obstetricians and pediatricians. The available evidence did not demonstrate a beneficial effect of either of obstetric strategies in the prevention of MAS.

Fetal heart rate monitoring: is it salvageable?

Fetal heart rate monitoring was introduced in the 1960s. After a number of randomized controlled trials in the mid 1980s, doubt arose regarding the efficacy of fetal heart rate monitoring in improving fetal outcome. The potential reasons why fetal heart rate monitoring has not been shown to be efficacious are (1) use of an outcome measure that is not related to variant fetal heart rate monitoring patterns, (2) lack of standardized interpretation of fetal heart rate patterns, (3) disagreement regarding algorithms for intervention of specific fetal heart rate patterns, and (4) the inability to demonstrate the reliability, validity, and ability of fetal heart rate monitoring to allow timely intervention. A recent National Institutes of Health committee proposed detailed, quantitative, standardized definitions of fetal heart rate patterns, which can serve as a basis for determining whether fetal heart rate monitoring is reliable and valid. In this article we examine reasons why fetal heart rate monitoring did not live up to its original expectations and why the randomized controlled trials did not demonstrate efficacy, and we make suggestions for determining whether electronic fetal heart rate monitoring should be abandoned.

Uncertain value of electronic fetal monitoring in predicting cerebral palsy

BACKGROUND

Electronic monitoring of the fetal heart rate is commonly performed, in part to detect hypoxia during delivery that may result in brain injury. It is not know whether specific abnormalities on electronic fetal monitoring are related to the risk of cerebral palsy.

METHODS

Among 155,636 children born from 1983 through 1985 in four California counties, we identified singleton infants with birth weights of at least 2500 g who survived to three years of age and had moderate or severe cerebral palsy. The children with cerebral palsy were compared with randomly selected control children with respect to characteristics noted in the birth records.

RESULTS

Seventy-eight of 95 children with cerebral palsy and 300 of 378 controls underwent intrapartum fetal monitoring. Characteristics found to be associated with an increased risk of cerebral palsy were multiple late decelerations in the heart rate, commonly defined as slowing of the heart rate well after the onset of uterine contractions (odds ratio, 3.9; 95 percent confidence interval, 1.7 to 9.3), and decreased beat-to-beat variability of the heart rate (odds ratio, 2.7; 95 percent confidence interval, 1.1 to 5.8); there was no association between the highest or lowest fetal heart rate recorded for each child and the risk of cerebral palsy. Even after adjustment for other risk factors, the association of abnormalities on fetal monitoring with an increased risk of cerebral palsy persisted (adjusted odds ratio, 2.7; 95 percent confidence interval, 1.4 to 5.4). The 21 children with cerebral palsy who had multiple late decelerations or decreased variability in heart rate on fetal monitoring represented only 0.19 percent of singleton infants with birth weights of 2500 g or more who had these fetal-monitoring findings, for a false positive rate of 99.8 percent.

CONCLUSIONS

Specific abnormal findings on electronic monitoring of the fetal heart rate were associated with an increased risk of cerebral palsy. However, the false positive rate was extremely high. Since cesarean section is often performed when such abnormalities are noted and is associated with risk to the mother, our findings arouse concern that, if these indications were widely used, many cesarean sections would be performed without benefit and with the potential for harm.

Antenatal antecedents of moderate and severe cerebral palsy

Aetiological relationships between cerebral palsy, preterm birth, small-for-gestational-age (SGA) birth and selected feto-maternal factors were investigated in a case-control study of all moderate and severe cerebral palsy cases born in Western Australia between 1980 and 1986 (n = 215). Cases were individually matched to three controls of the same gender and plurality born in the same year. Two of the controls were matched to the index cases for gestational age, one of which was also matched for birthweight. Pre-eclampsia and urinary tract infections were not significantly associated with cerebral palsy. The significant association of antepartum haemorrhage with cerebral palsy was accounted for by its associations with preterm birth. Congenital malformations and non-cerebral palsy neurological disorder were significantly associated with cerebral palsy; these associations were only partially accounted for by adjusting for preterm birth and small-for-gestational-age birth. This study shows that some of the risk of cerebral palsy associated with the antenatal antecedents of some common feto-maternal factors is mediated through preterm birth, confirming the importance of interrelationships between antenatal antecedents in the aetiology of some cerebral palsy. Perinatal and post-neonatal causes now account for only around 20% of all cerebral palsy. Future reductions in cerebral palsy incidence may therefore depend on acquiring greater knowledge of inter-relationships between antenatal antecedents.

Perinatal asphyxia: assessing its causal role and timing

Perinatal asphyxia, whether prenatal, intrapartum, or neonatal is thought to be a significant contributor to newborn morbidity and mortality as well as long-term neurological deficits. Development of an intrapartum tool/test that can reliably identify and discriminate between varying degrees of fetal acidemia and suggest whether it is respiratory or metabolic in nature would be highly desirable. This article critically reviews the available experience with the currently available monitoring techniques and the significance of abnormalities of fetal and intrapartum measurements with respect to the predictive value of the observations available to the clinician.

Relation between cerebral oxidative metabolism following birth asphyxia, and neurodevelopmental outcome and brain growth at one year

Studies of cerebral oxidative metabolism were carried out by phosphorous magnetic resonance spectroscopy during the first week of life in 52 infants with clinical and/or biochemical evidence of birth asphyxia. 15 infants died and the 37 survivors were assessed by a wide range of neurodevelopmental tests at one year of age. The minimum recorded values for cerebral phosphocreatine/inorganic phosphate concentration ratio (an index of oxidative metabolism) were related to outcome. The results showed a significant relation between the extent of derangement of oxidative metabolism and the severity of adverse outcomes, including death, neurodevelopmental impairment and reduced head growth.

Labor and delivery characteristics and the risk of germinal matrix hemorrhage in low birth weight infants

To assess the influence of labor and delivery events on the risk of germinal matrix hemorrhage in preterm newborns, we conducted a review of data collected on 449 babies who weighed 1.5 kg or less. Babies delivered vaginally were more likely to have germinal matrix hemorrhage than were babies delivered abdominally (odds ratio, 2.5; 95% confidence interval, 1.4,3.3). Among babies delivered vaginally, the risk of germinal matrix hemorrhage was increased by 39% if labor lasted more than 12 hours. Among babies delivered abdominally, the occurrence of any labor was accompanied by a 150% increased risk of germinal matrix hemorrhage. The only indication for abdominal delivery associated with an increased risk of germinal matrix hemorrhage was impending amnionitis (odds ratio, 2.6; 95% confidence interval, 1.2,5.7), whereas the only indication associated with a decreased risk was preeclampsia (odds ratio, 0.2; 95% confidence interval, 0.6). Epidural and local anesthesia were associated with a reduced risk of germinal matrix hemorrhage among babies delivered abdominally. We conclude that delivery practices, or their indications, appear to influence the risk of germinal matrix hemorrhage in low birth weight babies.

Cerebral palsy among children born during the Dublin randomised trial of intrapartum monitoring

In a randomised trial involving 13,079 liveborn children intrapartum care by electronic fetal heart rate monitoring, with scalp blood sampling when indicated, was associated with a 55% reduction in neonatal seizures. Reassessment, when aged 4, of the 9 children in the intensively monitored group and 21 in the control group who survived after neonatal seizures showed that 3 such children in each group had cerebral palsy. A fourth child in the intensively monitored group with cerebral palsy had had transient abnormal neurological signs during the neonatal period. 8 other children in the intensively monitored group and 7 in the control group who had not had abnormal neurological signs in the neonatal period also had cerebral palsy. 16 (78%) of the total of 22 cases of cerebral palsy had not shown clinical signs suggestive of intrapartum asphyxia. Thus, compared with intermittent intrapartum monitoring, intensive monitoring has little, if any, protective effect against cerebral palsy.

Fetal heart rate patterns, perinatal asphyxia, and brain injury

Hypoxic-ischemic injury, occurring during the intrapartum period, remains the most controversial perinatal cause of central nervous system injury. Current evidence suggests that injury during the intrapartum period is uncommon. The most widely used technique for antenatal surveillance is fetal heart rate monitoring. Fetal heart rate abnormalities, however, are infrequently associated with long-term adverse outcomes. Fetuses may manifest many minutes of "ominous" fetal heart rate patterns without evidence of irreversible central nervous system injury. Neurologically abnormal fetuses also may manifest abnormal fetal heart rate patterns because of neural mechanisms controlling heart rate, rather than because of intrapartum hypoxic events. Fetal acidosis also correlates poorly with outcome. The conclusion that a child's neurologic abnormalities are due to brain injury occurring during the intrapartum period cannot be based on fetal surveillance findings in isolation, but must be based on the consideration of many parameters.