Acid-base status at birth and neurodevelopmental outcome at four and one-half years

Umbilical cord blood acid-base analysis at birth and long-term neurodevelopmental outcomes in children: a systematic review and meta-analysis

BACKGROUND

Umbilical cord blood acid-base sampling is routinely performed at many hospitals. Recent studies have questioned this practice and the association of acidosis with cerebral palsy.

OBJECTIVE

To investigate the associations between the results of umbilical cord blood acid-base analysis at birth and long-term neurodevelopmental outcomes and mortality in children.

SEARCH STRATEGY

We searched six databases using the search strategy: umbilical cord AND outcomes.

SELECTION CRITERIA

Randomised controlled trials, cohorts and case-control studies from high-income countries that investigated the association between umbilical cord blood analysis and neurodevelopmental outcomes and mortality from 1 year after birth in children born at term.

DATA COLLECTION AND ANALYSIS

We critically assessed the included studies, extracted data and conducted meta-analyses comparing adverse outcomes between children with and without acidosis, and the mean proportions of adverse outcomes. The certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluations approach.

MAIN RESULTS

We have very low confidence in the following findings: acidosis was associated with higher cognitive development scores compared with non-acidosis (mean difference 5.18, 95% CI 0.84-9.52; n = two studies). Children with acidosis also showed a tendency towards higher risk of death (relative risk [RR] 5.72, 95% CI 0.90-36.27; n = four studies) and CP (RR 3.40, 95% CI 0.86-13.39; n = four studies), although this was not statistically significant. The proportion of children with CP was 2.39/1000 across the studies, assessed as high certainty evidence.

CONCLUSION

Due to low certainty of evidence, the associations between umbilical cord blood gas analysis at delivery and long-term neurodevelopmental outcomes in children remains unclear.

Umbilical cord pH, blood gases, and lactate at birth: normal values, interpretation, and clinical utility

Normal birth is a eustress reaction, a beneficial hedonic stress with extremely high catecholamines that protects us from intrauterine hypoxia and assists in the rapid shift to extrauterine life. Occasionally the cellular O₂ requirement becomes critical and an O₂ deficit in blood (hypoxemia) may evolve to a tissue deficit (hypoxia) and finally a risk of organ damage (asphyxia). An increase in H⁺ concentration is reflected in a decrease in pH, which together with increased base deficit is a proxy for the level of fetal O₂ deficit. Base deficit (or its negative value, base excess) was introduced to reflect the metabolic component of a low pH and to distinguish from the respiratory cause of a low pH, which is a high CO₂ concentration. Base deficit is a theoretical estimate and not a measured parameter, calculated by the blood gas analyzer from values of pH, the partial pressure of CO₂, and hemoglobin. Different brands of analyzers use different calculation equations, and base deficit values can thus differ by multiples. This could influence the diagnosis of metabolic acidosis, which is commonly defined as a pH <7.00 combined with a base deficit ≥12.0 mmol/L in umbilical cord arterial blood. Base deficit can be calculated as base deficit in blood (or actual base deficit) or base deficit in extracellular fluid (or standard base deficit). The extracellular fluid compartment represents the blood volume diluted with the interstitial fluid. Base deficit in extracellular fluid is advocated for fetal blood because a high partial pressure of CO₂ (hypercapnia) is common in newborns without concomitant hypoxia, and hypercapnia has a strong influence on the pH value, then termed respiratory acidosis. An increase in partial pressure of CO₂ causes less increase in base deficit in extracellular fluid than in base deficit in blood, thus base deficit in extracellular fluid better represents the metabolic component of acidosis. The different types of base deficit for defining metabolic acidosis in cord blood have unfortunately not been noticed by many obstetrical experts and organizations. In addition to an increase in H⁺ concentration, the lactate production is accelerated during hypoxia and anaerobic metabolism. There is no global consensus on definitions of normal cord blood gases and lactate, and different cutoff values for abnormality are used. At a pH <7.20, 7% to 9% of newborns are deemed academic; at <7.10, 1% to 3%; and at <7.00, 0.26% to 1.3%. From numerous studies of different eras and sizes, it can firmly be concluded that in the cord artery, the statistically defined lower pH limit (mean -2 standard deviations) is 7.10. Given that the pH for optimal enzyme activity differs between different cell types and organs, it seems difficult to establish a general biologically critical pH limit. The blood gases and lactate in cord blood change with the progression of pregnancy toward a mixed metabolic and respiratory acidemia because of increased metabolism and CO₂ production in the growing fetus. Gestational age-adjusted normal reference values have accordingly been published for pH and lactate, and they associate with Apgar score slightly better than stationary cutoffs, but they are not widely used in clinical practice. On the basis of good-quality data, it is reasonable to set a cord artery lactate cutoff (mean +2 standard deviations) at 10 mmol/L at 39 to 40 weeks' gestation. For base deficit, it is not possible to establish statistically defined reference values because base deficit is calculated with different equations, and there is no consensus on which to use. Arterial cord blood represents the fetus better than venous blood, and samples from both vessels are needed to validate the arterial origin. A venoarterial pH gradient of <0.02 is commonly used to differentiate arterial from venous samples. Reference values for pH in cord venous blood have been determined, but venous blood comes from the placenta after clearance of a surplus of arterial CO₂, and base deficit in venous blood then overestimates the metabolic component of fetal acidosis. The ambition to increase neonatal hemoglobin and iron depots by delaying cord clamping after birth results in falsely acidic blood gas and lactate values if the blood sampling is also delayed. Within seconds after birth, sour metabolites accumulated in peripheral tissues and organs will flood into the central circulation and further to the cord arteries when the newborn starts to breathe, move, and cry. This influence of "hidden acidosis" can be avoided by needle puncture of unclamped cord vessels and blood collection immediately after birth. Because of a continuing anaerobic glycolysis in the collected blood, it should be analyzed within 5 minutes to not result in a falsely high lactate value. If the syringe is placed in ice slurry, the time limit is 20 minutes. For pH, it is reasonable to wait no longer than 15 minutes if not in ice. Routine analyses of cord blood gases enable perinatal audits to gain the wisdom of hindsight, to maintain quality assurance at a maternity unit over years by following the rate of neonatal acidosis, to compare results between hospitals on regional or national bases, and to obtain an objective outcome measure in clinical research. Given that the intrapartum cardiotocogram is an uncertain proxy for fetal hypoxia, and there is no strong correlation between pathologic cardiotocograms and fetal acidosis, a cord artery pH may help rather than hurt a staff person subjected to a malpractice suit based on undesirable cardiotocogram patterns. Contrary to common beliefs and assumptions, up to 90% of cases of cerebral palsy do not originate from intrapartum events. Future research will elucidate whether cell injury markers with point-of-care analysis will become valuable in improving the dating of perinatal injuries and differentiating hypoxic from nonhypoxic injuries.

Gestational age-related reference values for Apgar score and umbilical cord arterial and venous pH in preterm and term newborns

INTRODUCTION

Despite much literature on reference values of acid-base status in umbilical cord blood at birth, there are as yet no studies performed to determine gestational age-dependent references in cord venous blood and no studies on preterm acid-base standards. Similarly, the normal reference range of Apgar scores for term and preterm infants has not yet been determined.

MATERIAL AND METHODS

Data were obtained from the maternity units of Skåne University Hospital, Malmö and Lund, Sweden, from 2001 to 2010. Validated paired arterial and venous cord pH values were obtained from 27 175 newborns, of whom 18 584 had spontaneous, non-instrumental vaginal deliveries and a 5-minute Apgar score equal to or greater than the median value for the individual gestational week. Simple linear and polynomial regression analyses were performed. Values were reported as mean ± standard deviation and median with 2.5th and 97.5th percentiles.

RESULTS

Median 5-minute Apgar score was 7 for gestations shorter than 28 weeks, 8 for 28 weeks, 9 for 29-30 weeks, and 10 from 31 weeks onwards. A linear decline in pH for both cord arterial and venous blood was seen with advancing gestational age (P < 0.001).

CONCLUSIONS

Median 5-minute Apgar scores were <10 before 31 weeks of gestation. Both umbilical cord arterial and venous pH decreased linearly with increasing gestational age. Further studies are needed to show whether gestational age-related pH reference ranges might be preferred to fixed cut-offs in the estimation of umbilical cord acidemia at birth.

Dose-dependent relationship between acidosis at birth and likelihood of death or cerebral palsy

BACKGROUND

The acid-base status of infants around birth can provide information about their past, current and future condition. Although umbilical cord blood pH <7.0 or base deficit ≥12 mmol/L is associated with increased risk of adverse outcome, there is uncertainty about the prognostic value of degree of acidosis as previous studies have used different variables, thresholds, outcomes and populations.

METHODS

Retrospective review of routinely collected clinical data in all live-born inborn infants of 35 weeks gestation or more delivered between January 2005 and December 2013 at the Simpson Centre for Reproductive Health, Edinburgh, UK. Infants were included if their lowest recorded pH was <7 and/or highest base deficit ≥12 mmol/L on either umbilical cord blood and/or neonatal blood gas within 1 hour of birth. Neurodevelopmental outcome of the infants with encephalopathy was collected from the targeted follow-up database.

RESULTS

56 574 infants were eligible. 506 infants (0.9%) met inclusion criteria. Poor condition at birth and all adverse outcomes increased with worsening acidosis. Combined outcome of death or cerebral palsy was 3%, 10% and 40% at lowest pH of 6.9-6.99, 6.8-6.89 and <6.8, respectively, and 8%, 14% and 59% at a base deficit of 12-15.9, 16-19.9 and 20 mmol/L or more, respectively.

CONCLUSIONS

There is a dose-dependent relationship between the degree of acidosis within an hour of delivery, and the likelihood of adverse neonatal and later neurodevelopmental outcome in infants born at 35 weeks gestation or more.

Does obesity complicate regional anesthesia and result in longer decision to delivery time for emergency cesarean section?

BACKGROUND

Maternal obesity can cause problems with anesthesia and surgery which may be reflected in emergency cesarean sections (CS) as an increased decision-to-delivery interval (DDI).

AIM

To study the association of elevated maternal BMI with DDI and the failure of regional anesthesia.

METHODS

Eight hundred and forty-two consecutive emergency CSs during a period of 1 year in a tertiary hospital were studied retrospectively. DDIs were analyzed in Crash and < 30-min urgency categories (n = 528), while the time required to establish regional anesthesia and its success were analyzed for all emergency CS cases.

RESULTS

The urgency distribution of the CSs was 11%, 52%, and 37% in Crash, < 30-min, and > 30-min urgency categories respectively. Increased BMI was associated with longer DDI time in the < 30-min urgency category (33(13-176) vs. 38(18-118) min; P < 0.05 for BMI < 30 and > 35 group respectively). Regional anesthesia failures (new regional anesthesia, conversion to general anesthesia, or complaint of pain during surgery) took place in 3.7%, 6.8%, and 8.5% in the BMI < 30, 30-35, and > 35 groups respectively (P = 0.021). Epidural top-up resulted in shorter DDI and time delay between arrival at the operating room and skin incision across all urgency and BMI groups than combined spinal epidural (CSE) anesthesia.

CONCLUSION

Higher BMI was associated with longer DDI and more regional anesthesia failures. Epidural top-up was faster than CSE for establishing CS anesthesia.

Birth asphyxia measured by the pH value of the umbilical cord blood may predict an increased risk of attention deficit hyperactivity disorder

AIM

Although birth asphyxia is a major risk factor for neonatal and childhood morbidity and mortality, it has not been investigated much in relation to attention deficit hyperactivity disorder (ADHD). We examined whether birth asphyxia measured by the pH of the blood in the umbilical artery cord was associated with childhood ADHD.

METHOD

A population-based cohort of 295 687 children born in Finland between 1991 and 2002 was followed until December 31, 2007. ADHD was identified by the International Classification of Diseases, 10th edition, as a diagnosis of hyperkinetic disorder. We examined the risk of ADHD with varying pH values using Cox regression, taking time trends into consideration.

RESULTS

When compared to the reference group, a pH value below 7.10 was significantly associated with an increased risk of ADHD. The strongest risks were observed among children with a pH value <7.15 and a gestational age of <32 weeks. The pH value did not contribute much to the risk among children with an Apgar score of 0-3.

CONCLUSION

Birth asphyxia, defined by low pH value, may predict an increased risk of ADHD in childhood. The association between the pH value and ADHD was homogenous when stratified by gestational age and the Apgar score.

Litigation related to intrapartum fetal surveillance

The role of intrapartum care including cardiotocography (CTG) monitoring in cases of perinatal neurological injury receives considerable debate in both clinical and medicolegal settings. The debate, however, has distracted attention from fundamental questions about the timing, mechanism, and preventability of perinatal injury. CTG tracings are used as a surrogate for asphyxia with the timing of intervention ("rescue") predicated on the presumed severity of asphyxia. Using CTG in this way has prevented intrapartum stillbirth, but it has not reduced the long-term injury in part, because, contrary to popular belief, the majority of intrapartum fetal injuries are unassociated with severe hypoxia or severe neonatal depression. This article describes the timing and mechanisms, including mechanical factors, of intrapartum perinatal injury and the benefit of using the CTG, not for the purpose of "rescue", but for identifying risk factors for fetal injury and keeping the fetus out of harm's way.

Umbilical artery pH at birth and neurobehavioral outcome in early preterm infants: A cohort study

Objective:

The objective of the following study is to determine the effect of umbilical artery pH at birth on early neurobehavioral outcome of preterm infants as assessed by Neurobehavioral Assessment of Preterm Infants (NAPI) tool.

Materials and Methods:

Prospective cohort study conducted at the neonatal unit in a tertiary care center in North India. Preterm neonates < 34 weeks of gestation were enrolled at birth and divided into cases (umbilical artery pH < 7.2) and controls (umbilical artery pH > 7.2). At 34 weeks postconceptional age, the motor development and vigor (MDV) and alertness and orientation (AO) domains of neurobehavior were assessed by NAPI and compared among groups.

Results:

Hundred preterm neonates were enrolled in the study out of which 76 (30 cases and 46 controls) were finally analyzed. The groups were comparable in terms of gestational age, mode of delivery, birth weight and requirement of resuscitative measures at birth. There was no significant difference in incidence of meningitis, intraventricular hemorrhage, jaundice and hypoxic ischemic encephalopathy among the groups; however hypoglycemia was observed more commonly among cases. The MDV score (mean ± standard deviation [SD] [95% confidence interval]) was found to be significantly lower among cases compared to controls (37.0713 ± 13.616 [32.099-42.0431] vs. 47.506 ± 14.0692 [43.367-51.655]) (P = 0.002). Similarly, lower AO scores were observed among the cases.

Conclusion:

A low umbilical artery pH at birth is a predictor of poor early neurobehavioral outcome in preterm neonates.

Association between hypoxia and perinatal arterial ischemic stroke: a meta-analysis

BACKGROUND

Perinatal arterial ischemic stroke (AIS) occurs in an estimated 17 to 93 per 100000 live births, yet the etiology is poorly understood. Although investigators have implicated hypoxia as a potential cause of AIS, the role of hypoxia in AIS remains controversial. The aim of this study was to estimate the association between perinatal hypoxia factors and perinatal arterial ischemic stroke through a meta-analysis of published observational studies.

PATIENTS AND METHODS

A systematic search of electronically available studies published through July 2013 was conducted. Publication bias and heterogeneity across studies were evaluated and summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated with fixed-effects or random-effects models.

RESULTS

A total of 8 studies describing the association between perinatal hypoxia factors and neonatal arterial ischemic stroke (AIS) met inclusion criteria, and 550 newborns with AIS were enrolled. The associations were found for AIS: preeclampsia (OR 2.14; 95% CI, 1.25 to 3.66), ventouse delivery (OR 2.23; 95% CI, 1.26 to 3.97), fetal heart rate abnormalities (OR 6.30; 95% CI, 3.84 to 10.34), reduced fetal movement (OR 5.35; 95% CI, 2.17 to 13.23), meconium-stained liquor (OR 3.05; 95% CI, 2.02 to 4.60), low Apgar score (OR 5.77; 95% CI, 1.66 to 20.04) and resuscitation at birth (OR 4.59; 95% CI, 3.23 to 6.52). Our data did not show any significant change of the mean risk estimate for oxytocin induction (OR 1.33; 95% CI, 0.84 to 2.11) and low arterial umbilical cord ph (OR 4.63; 95% CI 2.14 to 9.98).

CONCLUSIONS

There is a significant association between perinatal hypoxia factors and AIS. The result indicates that perinatal hypoxia maybe one of causes of AIS. Large scale prospective clinical studies are still warranted.

Short term outcome of term newborns with unexpected umbilical cord arterial pH between 7.000 and 7.100

BACKGROUND

The relationship between cord arterial pH (CA-pH) > 7.000 and the neonatal outcome is not clear.

AIMS

To evaluate if asymptomatic infants born with unexpected cord arterial pH (CA-pH) between 7.000 and 7.100 develop clinical, biochemical, and instrumental signs of hypoxic cerebral, renal, and heart failure more frequently than symptomatic infants.

STUDY DESIGN

Term infants with CA-pH of 7.000-7.100 and appropriate birth weight were prospectively and consecutively enrolled and classified as asymptomatic, when they had no resuscitation, early respiratory distress or early abnormal neurologic signs, and symptomatic infants. Clinical, biochemical, and instrumental signs of hypoxic cerebral, renal, and heart failure were evaluated in the two groups.

RESULTS

A total of 53 infants were enrolled. Twenty-eight (53%) were asymptomatic. CA-pH was similar in both the groups, while the cTnI serum concentration in the first day of life and the occurrence of poor feeding were higher in the symptomatic than in asymptomatic infants. An arterial lactate level of ≥ 4.1 mmol/l measured in the first hour of life was an independent risk factor for the development of a symptomatic course.

CONCLUSIONS

In our population the majority of infants born with a CA-pH between 7.000 and 7.100 were asymptomatic and would not have needed immediate admission to the neonatal care unit. Symptomatic infants showed a higher occurrence of subclinical heart injury and poor feeding.

The relationship between umbilical cord arterial pH and serious adverse neonatal outcome: analysis of 51,519 consecutive validated samples

OBJECTIVE

To examine the relationship between umbilical cord pH at term and serious neonatal outcomes.

DESIGN

Observational cohort study.

SETTINGS

Deliveries within the Oxford Radcliffe Hospital NHS Trust between 1991 and 2009.

POPULATION

In all, 51,519 singleton, term, nonanomalous live neonates with validated umbilical cord arterial pH values.

METHODS

Absolute risks, relative risks with 95% confidence intervals, and numbers needed to harm were calculated for different levels of arterial pH across the entire range.

MAIN OUTCOME MEASURES

Neonatal encephalopathy with seizures and/or death, encephalopathy within 24 hours of birth, 5-minute Apgar scores and neonatal unit admission.

RESULTS

The median arterial pH was 7.22, interquartile range 7.17-7.27. The absolute risk of an adverse neurological outcome was significantly increased below 7.10 (0.36%) and was lowest between 7.26 and 7.30 (0.16%). Even below 7.00, the risk was only 2.95%. However, more than 75% of neonates with neurological outcomes examined, including seizures within 24 hours of birth, had a pH above 7.10. A small increase in risk was evident at higher pH levels.

CONCLUSION

The threshold pH for adverse neurological outcomes is 7.10 and the 'ideal' cord pH is 7.26-7.30. Above 7.00, however, neonatal acidaemia is weakly associated with adverse outcomes. Most neonates with neurological morbidity have normal cord pH values. Other variables must influence adverse outcomes and account for more of these than acidaemia. A better understanding of these is required before intrapartum fetal monitoring can improve.

Developmental outcome at 6.5 years after acidosis in term newborns: a population-based study

OBJECTIVES

Infants who develop encephalopathy after perinatal asphyxia have an increased risk of death and adverse neurologic outcome. Conflicting results exist concerning outcome in healthy infants with metabolic acidosis at birth. The aim of the current study was to evaluate whether metabolic acidosis at birth in term infants who appear healthy is associated with long-term developmental abnormalities.

METHODS

From a population-based cohort (14,687 deliveries), 78 infants were prospectively identified as having metabolic acidosis (umbilical artery pH < 7.05 and base deficit in the extracellular fluid >12.0 mmol/L). Two matched controls per case were selected. The child health and school health care records were scrutinized for developmental abnormalities.

RESULTS

Outcome measures at 6.5 years of age for 227 of 234 children (97%) were obtained. No differences were found concerning neurologic or behavioral problems in need of referral action or neurodevelopmental diagnosis in comparison of control children with acidotic children who had appeared healthy at birth, ie, had not required special neonatal care or had no signs of encephalopathy.

CONCLUSIONS

Infants born with cord metabolic acidosis and who appear well do not have an increased risk for neurologic or behavioral problems in need of referral actions or special teaching approaches at the age of 6.5 years.

[Cerebral palsy and perinatal asphyxia (II--Medicolegal implications and prevention)]

Obstetric litigation is a growing problem in developed countries and its escalating cost together with increasing medical insurance premiums is a major concern for maternity service providers, leading to obstetric practice cessation by many practitioners. Fifty-four to 74 % of claims are based on cardiotocographic (CTG) abnormalities and their interpretation followed by inappropriate or delayed reactions. A critical analysis is performed about the nine criteria identified by the American College of Obstetricians and Gynecologists and the American Academy of Pediatrics in their task force on Neonatal Encephalopathy and Cerebral Palsy: four essential criteria defining neonatal asphyxia and five other suggesting an acute intrapartum event sufficient to cause cerebral palsy in term newborns. The importance of placental histologic examination is emphasized in order to confirm sudden catastrophic events occurring before or during labor or to detect occult thrombotic processes affecting the fetal circulation, patterns of decreased placenta reserve and adaptative responses to chronic hypoxia. It may also exclude intrapartum hypoxia by revealing some histologic patterns typical of acute chorioamnionitis and fetal inflammatory response or compatible with metabolic diseases. Magnetic resonance imaging (MRI) of the infant's damaged brain is very contributive to elucidate the mechanism and timing of asphyxia in conjunction with the clinical picture, by locating cerebral injuries predominantly in white or grey matter. Intrapartum asphyxia is sometimes preventable by delivering weak fetuses by cesarean sections before birth, by avoiding some "sentinel" events, and essentially by responding appropriately to CTG anomalies and performing an efficient neonatal resuscitation. During litigation procedures, it is necessary to have access to a readable CTG, a well-documented partogram, a complete analysis of umbilical cord gases, a placental pathology and an extensive clinical work-up of the newborn infant including cerebral MRI. Malpractice litigation in obstetric care can be reduced by permanent CTG education, respect of national CTG guidelines, use of adjuncts such as fetal blood sampling for pH or lactates, regular review of adverse events in Clinical Risk Management (CRM) groups and periodic audits about low arterial cord pH in newborns, admission to neonatal unit, the need for assisted ventilation and the decision-to-delivery interval for emergency operative deliveries. Considering the fast occurrence of fetal cerebral hypoxic injuries, and thus despite an adequate management, many intrapartum asphyxias will not be preventable. Conversely, well-documented hypoxic-ischemic brain insults during the antenatal period do not automatically exclude intrapartum suboptimal obstetric care.

Strength of association between umbilical cord pH and perinatal and long term outcomes: systematic review and meta-analysis

OBJECTIVE

To evaluate the association between umbilical cord pH at birth and long term outcomes.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Medline (1966-August 2008), Embase (1980-August 2008), the Cochrane Library (2008 issue 8), and Medion, without language restrictions; reference lists of selected articles; and contact with authors.

STUDY SELECTION

Studies in which cord pH at birth was compared with any neonatal or long term outcome. Cohort and case-control designs were included.

RESULTS

51 articles totalling 481 753 infants met the selection criteria. Studies varied in design, quality, outcome definition, and results. Meta-analysis carried out within predefined groups showed that low arterial cord pH was significantly associated with neonatal mortality (odds ratio 16.9, 95% confidence interval 9.7 to 29.5, I(2)=0%), hypoxic ischaemic encephalopathy (13.8, 6.6 to 28.9, I(2)=0%), intraventricular haemorrhage or periventricular leucomalacia (2.9, 2.1 to 4.1, I(2)=0%), and cerebral palsy (2.3, 1.3 to 4.2, I(2)=0%).

CONCLUSIONS

Low arterial cord pH showed strong, consistent, and temporal associations with clinically important neonatal outcomes that are biologically plausible. These data can be used to inform clinical management and justify the use of arterial cord pH as an important outcome measure alongside neonatal morbidity and mortality in obstetric trials.

Associations between serum cortisol, cardiovascular function and neurological outcome following acute global hypoxia in the newborn piglet

Perinatal asphyxia is a significant contributor to neonatal brain injury. However, there is significant variability in neurological outcome in neonates after global hypoxia-ischemia. The aims of this study were to identify which physiological response/s during global hypoxia-ischemia influence the severity of brain injury and to assess their relative importance. Hypoxia/hypercapnia was induced in 20 anaesthetized piglets by reducing the inspired oxygen fraction to 10% and the ventilation rate from 30 to 10 breaths per minute for 45 min. Neurological outcome was assessed using functional markers including cerebral function amplitude (via electroencephalography) and cerebral impedance, and the structural marker microtubule associated protein-2 by immunohistochemistry at 6 h post hypoxia. Significant variability in neurological outcome was observed following the constant hypoxia/hypercapnia insult. There was a high degree of variability in cardiovascular function (mean arterial blood pressure and heart rate) and serum cortisol concentrations in response to hypoxia. More effective maintenance of cardiovascular function and higher serum cortisol concentrations were associated with a better outcome. These two variables were strongly associated with neurological outcome, and together explained 68% of the variation in the severity of neurological outcome. The variability in the cardiovascular and cortisol responses to hypoxia may be a more important determinant of neurological outcome then previously recognized.

A systematic review of the role of intrapartum hypoxia-ischemia in the causation of neonatal encephalopathy

The object of this review was to determine the incidence, morbidity, and mortality of an umbilical arterial pH < 7.0; the incidence of hypoxic-ischemic encephalopathy; and the proportion of cerebral palsy associated with intrapartum hypoxia-ischemia in nonanomalous term infants. A systematic review of the English language literature on the association between intrapartum hypoxia-ischemia and neonatal encephalopathy was conducted by using Pubmed and Embase. For nonanomalous term infants, the incidence of an umbilical arterial pH < 7.0 at birth is 3.7 of 1000, of which 51 of 297 (17.2%) survived with neonatal neurologic morbidity, 45 of 276 (16.3%) had seizures, and 24 of 407 (5.9%) died during the neonatal period. The incidence of neonatal neurologic morbidity and mortality for term infants born with cord pH < 7.0 was 23.1%. The incidence of hypoxic-ischemic encephalopathy is 2.5 of 1000 live births. The proportion of cerebral palsy associated with intrapartum hypoxia-ischemia is 14.5%. The vast majority of cases of cerebral palsy in nonanomalous term infants are not associated with intrapartum hypoxia-ischemia.

INTRAPARTUM ST ANALYSIS

The last century has seen dramatic developments in medical care as technological advances have been applied to both diagnosis and treatment. Some areas of obstetrics have been slow to benefit from these advances – and none more so than the care of the fetus in labour.

Impact of the severity of fetal distress on decision-to-delivery intervals for assisted vaginal delivery

To correlate the severity of fetal distress assessed retrospectively using the Dublin intrapartum fetal monitoring classification, with decision-to-delivery intervals (DDI) and neonatal outcome, a prospective 3-month study of 78 consecutive instrumental deliveries was conducted. There were 66 cardiotocographs (CTGs) with an 83% majority agreement on classification: it was agreed 95% of deliveries should be expedited for the 58 interpretable CTGs. Although the more abnormal CTG patterns resulted in shorter DDIs and greater neonatal acidaemia, there were no significant correlations. Acidosis was present in 14% with a suspicious, or 22% an ominous CTG pattern. Delivery as a trial in theatre doubled the DDI at 41.5 +/- 22.7 (mean +/- SD) min, compared with 18.1 +/- 8.1 min in the labour room (p < 0.0001), with one case of severe acidosis in the former group. The prolonged DDI with a trial of delivery in theatre could adversely compromise the already 'distressed' fetus and should be used only when clearly indicated.

The association between cord pH at birth and intellectual function in childhood

BACKGROUND

Acidemia at birth is very common but little is known about its long-term consequences.

AIM

To determine if pH at birth is related to established tests of intellectual function.

SUBJECTS

School children aged 6-8, for whom obstetric data were available, who had been delivered after labour at term, and had an umbilical cord arterial pH>7.00 (i.e. that was not extremely acidemic). STUDY DESIGN/OUTCOMES: Retrospective cohort study correlating birth and arterial pH data with childhood tests for non-verbal intelligence, grammar comprehension and literacy.

METHODS

Relationships between pH and cognitive measures were analysed with parametric correlations. Partial correlations were used to examine these relationships, controlling for possible confounding factors.

RESULTS

Arterial pH was significantly negatively correlated with literacy (p=0.001) and with non-verbal intelligence (p=0.033).

CONCLUSIONS

Lower arterial pH is associated with higher scores on literacy and non-verbal intelligence tests at ages 6-8. This is unlikely to be a chance finding and is further evidence that acidemia in isolation should not be considered an adverse outcome. Further research on the relationship between labour and long-term cognitive measures is required.

Management of shoulder dystocia: trends in incidence and maternal and neonatal morbidity

OBJECTIVE

To investigate trends in the incidence of shoulder dystocia, methods used to overcome the obstruction, and rates of maternal and neonatal morbidity.

METHODS

Cases of shoulder dystocia and of neonatal brachial plexus injury occurring from 1991 to 2005 in our unit were identified. The obstetric notes of cases were examined, and the management of the shoulder dystocia was recorded. Demographic data, labor management with outcome, and neonatal outcome were also recorded for all vaginal deliveries over the same period. Incidence rates of shoulder dystocia and associated morbidity related to the methods used for overcoming the obstruction to labor were determined.

RESULTS

There were 514 cases of shoulder dystocia among 79,781 (0.6%) vaginal deliveries with 44 cases of neonatal brachial plexus injury and 36 asphyxiated neonates; two neonates with cerebral palsy died. The McRoberts' maneuver was used increasingly to overcome the obstruction, from 3% during the first 5 years to 91% during the last 5 years. The incidence of shoulder dystocia, brachial plexus injury, and neonatal asphyxia all increased over the study period without change in maternal morbidity frequency.

CONCLUSION

The explanation for the increase in shoulder dystocia is unclear but the introduction of the McRoberts' maneuver has not improved outcomes compared with the earlier results.

LEVEL OF EVIDENCE

II.

Umbilical cord blood lactate: a valuable tool in the assessment of fetal metabolic acidosis

OBJECTIVE

The aim of the present study was (1) to evaluate the relationship between umbilical cord arterial blood lactate and pH, standard base excess (SBE), and actual base excess (ABE) at delivery and (2) to suggest a cut-off level of umbilical cord arterial blood lactate in predicting fetal asphyxia using ROC-curves, where an ABE value less than -12 was used as "gold standard" for significant intrapartum asphyxia.

STUDY DESIGN

This is a descriptive study of umbilical cord arterial blood samples from 2554 singleton deliveries. The deliveries took place at the Department of Obstetrics and Gynaecology, Hvidovre University Hospital, Copenhagen, Denmark where umbilical cord blood sampling and blood gas analysis is part of the routine assessment of all newborns.

RESULTS

We found significant correlations between lactate and pH (r=-0.73), lactate and SBE (r=-0.76), and lactate and ABE (r=-0.83). ROC-curves suggested a lactate cut-off level of 8mmol/l for indicating intrapartum asphyxia.

CONCLUSION

Lactate in arterial umbilical cord blood might be a more direct and accordingly more correct indicator of fetal asphyxia at delivery than pH and SBE (or ABE). Its potential as a predictor of neonatal outcome needs to be evaluated in future studies.

The impact of a trial of instrumental delivery in theatre on neonatal outcome

OBJECTIVE

To observe the effect of a trial of instrumental delivery in theatre on outcome for mother and baby.

DESIGN

A prospective observational study.

METHODS

Relevant maternal and neonatal data were collected for all instrumental deliveries of singleton viable pregnancies delivered over a three month period.

POPULATION

Two hundred and twenty nine consecutive deliveries conducted by ventouse or forceps because of fetal distress or dystocia.

SETTING

The maternity unit of a teaching hospital delivering around 6000 women annually.

MAIN OUTCOME MEASURES

The decision-to-delivery intervals (DDI), mode of delivery and neonatal condition at birth.

RESULTS

Sixty (26%) deliveries were managed as a trial in theatre, 46 (77%) because of prolonged second stage, with malposition being a factor in 39, and 14 (23%) because of fetal distress. The mean +/- SD DDI for these 60 deliveries was 59.2 +/- 20.4 minutes (median 58 minutes) compared with 21.2 +/- 9.0 minutes (median 20 minutes) for 169 delivered in the labour room (P < 0.0001). Of these 169 deliveries, 168 were delivered within 46 minutes and 1 delivered by caesarean section at 60 minutes. Nine women (13%) ultimately delivered by caesarean section, eight following a trial in theatre; in seven, there was malposition. Deliveries following a trial had slightly less favourable cord blood gas results.

CONCLUSIONS

Trial of instrumental delivery takes two to three times longer than delivery in the labour room; fetal malposition was the major indication for the trial of instrumental delivery and reason for failed delivery. Adopting the recent guidelines of the Royal College of Obstetricians and Gynaecologists, at least 107 (47%) should have been managed as a trial in theatre. The added delay in delivery could be damaging to an already hypoxic fetus, and the use of a trial should be individually assessed.

Acid-base status at birth, spontaneous motor behaviour at term and 3 months and neurodevelopmental outcome at age 4 years in full-term infants

OBJECTIVE

The aim of the study was to assess the relationship between acid-base status and quality and quantity of General Movements (GMs) at birth and quality of GMs at age 3 months and motor, cognitive and behavioural functioning at the age of 4 years.

METHODS

From a cohort of 84 term children with different umbilical artery pH without severe neonatal neurological abnormalities, GMs were assessed at term and at 3 months. At the age of 4 years, 44 children were assessed by means of the Movement Assessment Battery for Children (Movement-ABC), Neurological Examination for Toddlers of Hempel, Kaufman Assessment Battery for Children information processing (Kaufman ABC), Visuomotor Integration (VMI), the Child Behaviour Checklist (CBCL) and Precursors ADHD Questionnaire (PAQ).

RESULTS

We found no relationship between pH or GM-quality and quantity at term or GM-quality at 3 months and scores on most of the items of the Movement-ABC, cognitive and behavioural outcome. However, neonatal pH value and GM-quality at 3 months were related to some extent to the presence of subtle signs of neuromotor dysfunction as measured by the Hempel test.

CONCLUSIONS

In a sample of infants with a large variation in umbilical artery pH and without severe neonatal neurological abnormalities, acid-base status at birth and quality of GMs at 3 months of age is not predictive for motor milestone achievement, cognitive and behavioural functioning at 4 years, but these parameters are related to a less optimal condition of the nervous system. The latter finding has, however, limited clinical significance.

Birth asphyxia and cerebral palsy

There has been a societal presumption that most, if not all, cases of hypoxic ischemic encephalopathy-induced cerebral palsy occur during the 3 hours that are related to the events of labor and delivery; society has tended to overlook the remaining 7000 hours of the pregnancy. As a result of this societal perspective, often times the obstetrician has been targeted unfairly as the person who is responsible for a given child's neurologic injuries. Rather, the entire pregnancy, labor, delivery, and well beyond birth require examination to understand fully the pathophysiologic mechanisms that are responsible for an infant's brain injuries, and their long-term impact on the child.

Prediction of neonatal state by computer analysis of fetal heart rate tracings: the antepartum arm of the SisPorto® multicentre validation study

OBJECTIVE

To evaluate the capacity of computer analysis of antepartum cardiotocographs performed by SisPorto 2.0 in predicting neonatal outcome.

STUDY DESIGN

A prospective observational study was conducted in eight tertiary care centres in Europe and Australia, involving pregnant women in the absence of labor, scheduled for elective caesarean section, whose last fetal heart rate (FHR) tracing was performed within 4h of delivery. After exclusion of fetal malformations, multiple pregnancies, tracings with less than 30 min, tracings with more than 15% signal loss, difficult fetal extractions, and anesthesia complications, a total of 345 cases were analyzed. Computer quantification of cardiotocographic parameters was compared with newborn Apgar score, umbilical artery pH, metabolic acidosis and neonatal hypoxic-ischemic encephalopathy, by means of receiver operating characteristic (ROC) curves.

RESULTS

Acceleration number, mean short-term variability, percentage of abnormal short-term variability and percentage of abnormal long-term variability had an excellent discriminative capacity to predict 1-min Apgar scores under or equal to 4 (areas under the ROC curve 0.96-1.00). The same parameters showed a slightly lower capacity to predict 5-min Apgar scores under or equal to 6 (areas under the ROC curve 0.81-0.89). The best cut-off values for these parameters, derived from the previously referred calculations, detected all cases of hypoxic-ischemic encephalopathy (n = 2). Cardiotocographic parameters showed a lower discriminative capacity in prediction of umbilical artery pH <7.20 (maximum area under the ROC curve 0.66) and <7.15 (maximum area under the ROC curve 0.69).

CONCLUSIONS

Computerized quantification of accelerations and variability in the antepartum allows a good prediction of 1 and 5-min Apgar scores, and to a much lesser degree umbilical artery pH.

Umbilical artery blood gas parameters in neonates with early onset seizures who die

OBJECTIVE

To relate umbilical artery blood gas parameters to mortality among neonates with hypoxic-ischaemic encephalopathy related to early onset seizures.

DESIGN

Population cohort study.

SETTING

British Columbia Women's Hospital.

POPULATION

Forty-seven infants at >or=32 weeks of gestation admitted to NICU with early onset seizures secondary to hypoxic-ischaemic encephalopathy with umbilical artery blood gases done at delivery.

METHODS

Patients were divided into two groups: (1) Infants with neonatal seizures who survived, and (2) infants with neonatal seizures who died related to hypoxic-ischaemic encephalopathy complications. Comparison of umbilical artery pH, PO(2), PCO(2), base deficit was done between the two groups with Student's t tests.

MAIN OUTCOME MEASURES

Umbilical artery pH, PO(2), PCO(2) and base deficit.

RESULTS

The PO(2) was significantly higher in the group that expired (18.36 +/- 9.15 vs 12.33 +/- 7.51). There were no significant differences in any other blood gas parameters between the groups.

CONCLUSION

Neither the umbilical artery pH nor base deficit is predictive of neonatal death in infants with hypoxic-ischaemic encephalopathy with seizures. The finding of a high PO(2) in neonates who died may indicate an inability of those infants to efficiently extract oxygen from blood.

Low Apgar scores and the definition of birth asphyxia

Nonreassuring fetal heart rate patterns, prolonged labor, meconium-stained fluid, a low 1-minute Apgar score, and mild to moderate acidemia have no predictive value for long-term neurologic injury without signs of encephalopathy and seizures. It is important to provide proper resuscitation, support infants, and allow time for evaluation. We have time and the tools to provide fairly predictive information to the families. It is important to use this knowledge wisely in communicating honestly with families, because difficult decisions undoubtedly will arise.

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.

Cerebral (31)P magnetic resonance spectroscopy and systemic acid-base balance during hypoxia in fetal sheep

The purpose of this study was to investigate cerebral energy metabolism and acid-base homeostasis during impaired oxygen supply in fetal sheep. Systemic acid-base balance was correlated with the sequence in changes of cerebral phosphorus metabolite ratios and intracellular pH. Phosphorus magnetic resonance spectra were obtained from the brain of six fetal sheep simultaneously with repeated measurements of fetal arterial oxygen saturation and acid-base balance. Fetal hypoxia was induced by gradually reducing the oxygen supply to the anesthetized pregnant ewe to establish an intended arterial pH of 7.00 or lower. The ratio of phosphocreatine to inorganic phosphate decreased from 1.08 +/- 0.10 (SD) during the control period to 0.77 +/- 0.29 at an arterial pH between 7.20 and 7.25. The inorganic phosphate level became significantly increased at an arterial pH between 7.10 and 7.15 compared with control values. With ongoing arterial acidosis, cerebral intracellular pH decreased linearly with the arterial pH. At an arterial pH of 7.00, cerebral intracellular pH was decreased from 7.18 +/- 0.03 to 6.71 +/- 0.28, and phosphocreatine and nucleoside triphosphates levels were decreased significantly. In fetal sheep brain, cerebral oxidative phosphorylation (ratio of phosphocreatine to inorganic phosphate) is already affected at a mild arterial acidosis. At an arterial pH of 7.00 or lower, nucleoside triphosphates disappeared, which almost inevitably was followed by death in fetal sheep.

Evidence of intrapartum hypoxia-ischemia is not present in the majority of cases of neonatal seizures

OBJECTIVE

To determine the extent to which neonatal seizures are associated with intrapartum hypoxia-ischemia.

METHODS

In this case-control study, all neonates diagnosed with seizures at a single institution from 1988 to 1999 were compared to a control group without seizures matched in a 2:1 fashion for gestational age at delivery, birth weight and mode of delivery. Data were abstracted from the maternal and neonatal charts. Parametric variables were compared using an independent samples t test, and non-parametric variables were compared using a Fisher exact test, with p < 0.05 being considered significant.

RESULTS

There were 13 cases of neonatal seizures identified, of which one was chromosomally abnormal and excluded from further analysis. For the cases, the mean gestational age at delivery was 34.8 +/- 6.9 weeks, with four preterm and eight term deliveries. The mean birth weight for the cases was 2684 +/- 1369 g (range 590-4350 g). For both cases and controls, 83% were delivered vaginally and 17% by Cesarean section. For term neonates with seizures, the mean length of stay was 11.6 +/- 5.0 days, as compared to 2.5 +/- 0.9 days in the control group (p < 0.001). A 1-min Apgar score of < 7 was found in six of 12 (50%) cases and seven of 24 (29%) controls, and a 5-min Apgar score of < 7 was found in four of 12 (33%) cases and four of 24 (17%) controls (non-significant). In the controls, the mean base excess was -2.8 +/- 2.6 mEq/l, and the mean umbilical arterial pH was 7.28 +/- 0.09. In the case group, two infants born at 24 weeks did not have an umbilical arterial blood gas obtained; in the remaining cases, the mean base excess was -7.6 +/- 6.9 mEq/l (p = 0.02), and the mean cord pH was 7.17 +/- 0.23 (p = 0.065), with only three of ten (30%) having a pH < 7.00 (p = 0.02).

CONCLUSION

Clinically significant acidosis was found in only 30% of neonates who developed seizures, and only one of 12 cases (8%) could possibly have met the criteria of the American College of Obstetricians and Gynecologists for neurological morbidity linked to intrapartum asphyxia. The majority of cases of neonatal seizures were not associated with evidence of intrapartum hypoxia-ischemia.

What is a reasonable time from decision-to-delivery by caesarean section? Evidence from 415 deliveries

OBJECTIVE

To determine how long it takes from the decision to achieve delivery by non-elective caesarean section (DDI), the influences on this interval, and the impact on neonatal condition at birth.

DESIGN

Twelve months prospective data collection on all non-elective caesarean sections.

METHODS

Prospective collection of data relating to all caesarean sections in 1996 in a major teaching hospital obstetric unit was conducted, without the knowledge of the other clinicians providing clinical care. Details of the indication for section, the day and time of the decision and the interval till delivery were recorded as well as the seniority of the surgeon, and condition of the baby at birth.

RESULTS

The mean time from decision-to-delivery for 100 emergency intrapartum caesarean sections was 42.9 minutes for fetal distress and 71.1 minutes for 230 without fetal distress (P < 0.0001). For 22 'crash' sections the mean time from decision-to-delivery was 27.4 minutes; for 13 urgent antepartum deliveries for fetal reasons it was 124.7 minutes and for 21 with maternal reasons it was 97.4 minutes. The seniority of the surgeon managing the patient did not appear to influence the interval, nor did the time of day or day of the week when the delivery occurred. Intrapartum sections were quicker the more advanced the labour, and general anaesthesia was associated with shorter intervals than regional anaesthesia for emergency caesarean section for fetal distress (P < 0.001). Babies born within one hour of the decision tended to be more acidaemic than those born later, irrespective of the indication for delivery. Babies tended to be in better condition when a time from decision-to-delivery was not recorded than those for whom the information had been recorded.

CONCLUSION

Fewer than 40% intrapartum deliveries by caesarean section for fetal distress were achieved within 30 minutes of the decision, despite that being the unit standard. There was, however, no evidence to indicate that overall an interval up to 120 minutes was detrimental to the neonate unless the delivery was a 'crash' caesarean section. These data thus do not provide evidence to sustain the recommendation of a standard of 30 minutes for intrapartum delivery by caesarean section.

Long-term developmental outcome of asphyxiated term neonates

Asphyxia remains one of the main causes of later disability in term infants. Despite many publications identifying possible predictors of outcome in this population of interest, little is known of the long-term developmental outcome of asphyxiated term neonates. Observational studies have largely focused on short-term outcomes, with an emphasis on significant neurologic sequelae and intellectual impairments. This article reviews the literature that has described the developmental outcome of asphyxiated term newborns. As part of this review, we have also highlighted the evolution of the definition of asphyxia and delineated appropriate markers that should be used in future research on this population.

Hypoxic-ischemic brain injury in the newborn: pathophysiology and potential strategies for intervention

There is increasing clinical and experimental data describing the evolution of hypoxic-ischemic encephalopathy in the perinatal period. Outcome to the fetus is determined not only by the impact of gross asphyxial insult, but also external factors that sensitize the brain to injury. Delayed neuronal and glial death occurring in the hours and days after the insult by apoptotic and related processes are observed following severe injury, and offer the most promise for pharmacological intervention. Furthermore, new technologies allow the identification of subtle insults with evolving encephalopathies that have implications for long-term neurological outcome. Application of this knowledge will allow us to identify strategies for early intervention and prevent the course of damage caused by hypoxic-ischemic injury.

An international network for evaluating neuroprotective therapy after severe birth asphyxia

Animal studies have shown great promise in their applicability to potentially neuroprotective therapies for severe birth asphyxia in human babies. It is now necessary to consider a strategy to evaluate some or all of these techniques within the context of human neonatal randomized control trials (RCT). We have set up a pilot study for an international RCT of mature babies with severe asphyxia (defined by an Apgar score of 5 or less at 10 minutes) and have shown that we can recruit from 120 centers in 17 countries an average of three babies a week, which is the required number to undertake a study over a 2-year period with sufficient power to show a significant improvement in outcome. Particular attention must be given in future studies to the size of improvement in outcome required, generalizability of entry criteria, and the appropriate measure of functional outcome in treated babies.

Acute fetal asphyxia and permanent brain injury: a retrospective analysis of current indicators

OBJECTIVE

To determine whether a term neonate who has had sufficient intrapartum asphyxia to produce persistent brain injury will manifest the following four criteria: profound acidemia (arterial pH <7.00), an APGAR score < or =3 for 5 min or longer, seizures within 24 h of birth, and multiorgan system dysfunction.

METHODS

Singleton, liveborn, neurologically impaired neonates > or =37 weeks gestation who lived at least 6 days and had sufficient documentation of current intrapartum asphyxia criteria were retrospectively analyzed. Of these infants, solely neonates with acute fetal asphyxia due to a sudden prolonged FHR deceleration that lasted until delivery from a catastrophic event, e.g., uterine rupture, cord prolapse, were included. Organ system dysfunction was defined by separate criteria for each organ system. Dysfunction in one or more was defined as multiorgan system dysfunction.

RESULTS

Of the 292 eligible infants in the registry, 47 satisfied the entry criteria. In these 47 neonates, 10 (21%) satisfied all 4 criteria for intrapartum asphyxia.

CONCLUSIONS

Our retrospective study suggests that currently used indicators to define permanent fetal brain injury are not valid.

Newborn assessment and long-term adverse outcome: a systematic review

The medical literature was searched for publications between 1966 and September 1997 for data on the association of Apgar score, umbilical blood pH, or Sarnat grading of encephalopathy with long-term adverse outcome. Odds ratios for these associations were combined to calculate common odds ratios with 95% confidence intervals. Our search identified abstracts of 1312 studies and 81 articles with sufficient numeric data to formulate contingency tables. Forty-two of these qualified for inclusion in our meta-analysis. The strongest associations in the prediction of neonatal death were found by comparing umbilical artery pH <7 with pH >/=7 (common odds ratio 43; 95% confidence interval 15-124) and by comparing Sarnat grade III with grade II (common odds ratio 24; 95% confidence interval 13-45). In the prediction of cerebral palsy, the strongest associations were found for Sarnat grade III versus grade II (common odds ratio 20; 95% confidence interval 6-70) and for 20-minute Apgar score 0 to 3 versus 4 to 6 (common odds ratio 15; 95% confidence interval 5-50).

Does the onset of neonatal seizures correlate with the timing of fetal neurologic injury?

The onset of seizures after birth has been considered evidence of an intrapartum asphyxial event. The present study was undertaken to determine whether the timing of neonatal seizures after birth correlated with the timing of a fetal asphyxial event. Thus, singleton term infants diagnosed with hypoxic ischemic encephalopathy and permanent brain injury had a mean birth to seizure onset interval of 9.8 +/- 17.7 (range 1-90) hours. When these infants were categorized according to their fetal heart rate (FHR) patterns, the acute group (normal FHR followed by a sudden prolonged FHR deceleration that continued until delivery) tended to have earlier seizures than infants did within the tachycardia group (normal FHR followed by tachycardia, repetitive decelerations, and diminished variability) and the preadmission group (persistent nonreactive FHR pattern intrapartum). These seizure intervals were as follows: acute, 6.6 +/- 18.0 (range 1-90) hours; tachycardia, 11.1 +/- 17.1 (range 1-61) hours; and preadmission, 11.8 +/- 17.9 (range 1-79) hours (p < 0.05). But the range varied widely and no group was categorically distinct. In conclusion, the onset of neonatal seizures after birth does not, in and of itself, appear to be a reliable indicator of the timing of fetal neurologic injury.