Maternal fever and neonatal depression: preliminary observations

Potential impact of epidural labor analgesia on the outcomes of neonates and children

This review summarizes recent evidences regarding the potential influences of epidural labor analgesia (ELA) on the outcomes of neonates and children. Terms and relevant words including “ELA,” “ELA and neonatal outcomes,” “ELA and children's development,” and “ELA and children's neurocognitive development” were used to search articles published in PubMed database up to October 2019. Original articles and reviews regarding potential influences of ELA on neonates and children were identified. Relevant references of the selected articles were also screened. The anesthetics used during ELA can be absorbed, enter the fetus, and produce neonatal depression; however, these effects are less severe than those during systematic opioid analgesia. The impact of anesthetic exposure during ELA on children's neurodevelopment has not been fully studied, but would be mild if any. ELA increases the risk of intrapartum maternal fever; the latter may be harmful to neonatal outcomes. The use of ELA may increase birth injury by increasing instrumental delivery, although long-term adverse events are rare. On the other hand, ELA may reduce maternal depression and, thus, produce favorable effects on neurocognitive development in childhood; but evidences are still lacking in this aspect. ELA may produce both favorable and unfavorable effects on neonates and children. These effects should be discussed with parturient women before making decisions. The potential harmful effects should be carefully managed. The overall impacts of ELA on neonatal and children's outcomes need to be studied further.

A Global View of Neonatal Asphyxia and Resuscitation

Birth asphyxia (BA), assumed to be related to intrapartum related hypoxia-ischemia, accounts for one million neonatal deaths annually. In the low resource setting BA is usually defined as a failure to initiate or sustain spontaneous breathing at birth. In the resource replete setting BA is a biochemical definition related to impaired gas exchange, due to interruption of placental blood flow (PBF). An umbilical arterial pH <7.00 referred to as severe fetal acidemia, reflects a degree of acidosis, where potential risk of adverse neurologic sequelae is increased. However, even with this degree of acidemia, the likelihood of mortality or adverse neurologic sequelae remains low. The aim is to focus on the definition of BA in the low resource setting, and compare it to the diagnosis in the resource replete setting, highlighting the importance of interruption of placental blood flow as it relates to morbidity and mortality. With asphyxia, the fetus aims to redistribute cardiac output to protect more vital organs e.g., brain, myocardium, and adrenal gland at the expense of decreased flow to organs such as kidney or intestine. In an experimental newborn model, animals subjected to asphyxia immediately develop primary apnea with bradycardia sustained blood pressure and normal pH. Recovery of respirations follows basic interventions, i.e. stimulation coupled with reversal of asphyxia. However, if asphyxia is sustained, secondary apnea manifests with bradycardia, hypotension, and pH <7.00. More intensive resuscitation including bag mask ventilation ± intubation ± cardio-pulmonary resuscitation may be necessary for correction upon reversal of asphyxia. Identification of a severely acidemic state (cord arterial pH < 7.00) in the newborn, may help to differentiate the truly asphyxiated intrapartum related cases that result in mortality, from those cases where mortality is related to delay in or ineffective basic resuscitation.

Epidural Labor Analgesia and Maternal Fever

Women receiving an epidural for labor analgesia are at increased risk for intrapartum fever. This relationship has been supported by observational, before and after, and randomized controlled trials. The etiology is not well understood but is likely a result of noninfectious inflammation as studies have found women with fever have higher levels of inflammatory markers. Maternal pyrexia may change obstetric management and women are more likely to receive antibiotics or undergo cesarean delivery. Maternal pyrexia is associated with adverse neonatal outcomes. With these consequences, understanding and preventing maternal fever is imperative.

Association between Intrapartum Magnesium Administration and the Incidence of Maternal Fever: A Retrospective Cross-sectional Study

BACKGROUND

Intrapartum maternal fever is associated with several adverse neonatal outcomes. Intrapartum fever can be infectious or inflammatory in etiology. Increases in interleukin 6 and other inflammatory markers are associated with maternal fever. Magnesium has been shown to attenuate interleukin 6-mediated fever in animal models. We hypothesized that parturients exposed to intrapartum magnesium would have a lower incidence of fever than nonexposed parturients.

METHODS

In this study, electronic medical record data from all deliveries at Northwestern Memorial Hospital (Chicago, Illinois) between 2007 and 2014 were evaluated. The primary outcome was intrapartum fever (temperature at or higher than 38.0°C). Factors associated with the development of maternal fever were evaluated using a multivariable logistic regression model. Propensity score matching was used to reduce potential bias from nonrandom selection of magnesium administration.

RESULTS

Of the 58,541 women who met inclusion criteria, 5,924 (10.1%) developed intrapartum fever. Febrile parturients were more likely to be nulliparous, have used neuraxial analgesia, and have been delivered via cesarean section. The incidence of fever was lower in women exposed to magnesium (6.0%) than those who were not (10.2%). In multivariable logistic regression, women exposed to magnesium were less likely to develop a fever (adjusted odds ratio = 0.42 [95% CI, 0.31 to 0.58]). After propensity matching (N = 959 per group), the odds ratio of developing fever was lower in women who received magnesium therapy (odds ratio = 0.68 [95% CI, 0.48 to 0.98]).

CONCLUSIONS

Magnesium may play a protective role against the development of intrapartum fever. Future work should further explore the association between magnesium dosing and the incidence of maternal fever.

A state-wide assessment of the association between epidural analgesia, maternal fever and neonatal antibiotics in Colorado, 2007-2012

OBJECTIVE

To determine if an association exists between epidural analgesia, maternal fever and neonatal antibiotic exposure in a state-wide birth cohort.

DESIGN, SETTING AND PARTICIPANTS

We performed a retrospective cohort study of the population-based Colorado Department of Public Health and Environment birth certificate database. Data included all reported births in the state of Colorado between 2007 and 2012. Live, non-preterm, vaginal, singleton, in-hospital births were included in analysis.

EXPOSURE

Maternal epidural analgesia and maternal fever.

MAIN OUTCOMES MEASURES

Neonatal antibiotic treatment for suspected sepsis. A stratified analysis was conducted to evaluate whether epidural use was an effect modifier of the association between maternal fever and neonatal antibiotic treatment.

RESULTS

The final cohort included 261 457 births. 2.2% of women who received an epidural had a fever, as compared with 0.4% of women who did not receive an epidural (OR: 5.4; 95% CI 4.9 to 6.0), and neonates born to women who received an epidural had 1.26 times increased odds of antibiotic treatment (95% CI 1.1 to 1.4). Stratification by epidural use did not alter the association between maternal fever and neonatal antibiotic treatment.

CONCLUSIONS

Colorado providers treat neonates born to mothers with maternal fever without respect to whether the mother had an epidural. Further research into improved criteria for neonatal sepsis evaluation that accounts for the contribution of maternal epidural fever should be developed to decrease unnecessary neonatal antibiotic exposure.

Maternal Race/Ethnicity and Predictors of Pregnancy and Infant Outcomes

Objective. To examine predictors of pregnancy and infant outcomes, including maternal race/ethnicity. Design. Prospective and observational follow-up of high-risk pregnancies and births. Participants. Three hundred fifty-four mothers and their preterm and/or high-risk live-born neonates were closely followed in three tertiary care centers from the prenatal to postnatal periods for potential high-risk and/or preterm births that required neonatal resuscitations. Major Outcome Measures. Pregnancy complications, birth complications, and infant outcomes were examined in conjunction with maternal factors, including preexisting health problems, health behaviors (smoking, alcohol consumption, prenatal visits), and the birth setting (tertiary care centers or community hospitals). Results. About 22% of these infants were transferred into the tertiary care centers from the community hospitals right after birth; the rest were born in the centers. According to regression analyses, predictors of the birth setting were race (White vs. non-White), maternal health behaviors, pregnancy complications, fetal distress, and the presence of congenital defects for infants (p < .001). Predictors for fetal distress included race (Whites) and pregnancy-induced hypertension (p < .003). Predictors for lower birth weight included race (non-Whites), maternal cigarette smoking, pregnancy complications, fetal distress, and congenital defects (p < .001). Infant mortality rate was 3.9% for these high-risk infants, with the highest rate in infants born to Black mothers (8%). Conclusions. There are obvious health disparities among White and non-White women experiencing high-risk pregnancies and births. Future studies are needed to develop interventions targeted to different racial/ethnic groups during pregnancy to reduce preterm and high-risk births.

The importance of temperature on the neurovascular unit

Therapeutic hypothermia is the only treatment that has been shown to be of benefit to infant's ≥ 36 weeks of gestation with hypoxic-ischemic encephalopathy. The evidence for the benefit is based on multiple, well-designed randomized clinical trials. Based on this data, the use of therapeutic hypothermia has been widely disseminated throughout the neonatal community. An important concept in hypoxic-ischemic brain injury is the functioning of the neurovascular unit which links neurons, non-neuronal cellular elements and the capillary endothelial cells to promote optimal barrier maintenance between the brain and systemic circulation, regulation of blood flow and neuro-immunologic functioning. Hypoxic-ischemic injury can trigger increased permeability of the blood-brain-barrier via molecular events within the neurovascular unit and initiate pathways to brain injury. In addition, exposure of the brain to cellular elements from the systemic circulation can further propagate the neuro-inflammatory response. The influence of temperature on injury to the neurovascular unit has received relatively little attention. This review will focus on one component of the neurovascular unit, the blood-brain barrier and its constituents. Specifically, this review will address the effects of hypoxia-ischemia and temperature on the neurovascular unit and potential knowledge gaps which may serve as areas for further investigation.

The association between epidural labor analgesia and maternal fever

The association between epidural labor analgesia and maternal fever is complex and controversial. Observational, retrospective, before-and-after, and randomized controlled trials all support the association, with the most current evidence supporting the mechanistic involvement of noninfectious inflammation. Considering the clinically significant neonatal consequences that have been previously demonstrated, and the possibility of more common subclinical fetal brain injury that animal models imply, the avoidance of maternal fever during labor is imperative. With the current popularity of epidural analgesia in labor, it is important that clinicians delineate how epidurals cause maternal fever and how to block the noninfectious inflammatory response that seems to warm a subset of women laboring with epidurals.

Meconium-stained amniotic fluid and the need for paediatrician attendance

AIM

To determine perinatal parameters among term newborn infants born by vaginal delivery with meconium-stained amniotic fluid (MSAF) that needed paediatrician assistance.

METHODS

Paediatricians who were in attendance in the delivery room due to MSAF among term infants completed 775 reports regarding the infants' delivery conditions, and the assistance provided. We defined 'paediatrician attendance needed' for a subgroup of infants for whom we retrospectively determined that paediatrician attendance in the delivery room was required.

RESULTS

'Paediatrician attendance needed' was determined in 31 (4%) cases. Among cases with documented normal foetal monitor, only 10 (1.8%) were defined as 'paediatrician attendance needed', a percentage significantly lower than among infants born following non-reassuring foetal monitor: 21 (9.7%) (p < 0.001). 'Paediatrician attendance needed' was predicted by non-reassuring foetal monitor [OR 6.02 (CI 2.72-13.31), p < 0.001], maternal fever [OR 6.34 (1.92-20.92), p = 0.002] and younger maternal age (for every year) [OR 0.889 (CI 0.82-0.96), p = 0.003].

CONCLUSIONS

Term newborn infants born by vaginal delivery with MSAF with documented normal tracing foetal monitor are at low risk of the need for paediatrician assistance. Paediatrician attendance in the delivery room in labour involving MSAF should be recommended when non-reassuring foetal monitor tracing is observed and should also be considered when maternal fever is recorded, and/or thick meconium is observed.

Intrapartum temperature elevation, epidural use, and adverse outcome in term infants

OBJECTIVES

To examine the association of intrapartum temperature elevation with adverse neonatal outcome among low-risk women receiving epidural analgesia and evaluate the association of epidural with adverse neonatal outcome without temperature elevation.

METHODS

We studied all low-risk nulliparous women with singleton pregnancies ≥37 weeks delivering at our hospital during 2000, excluding pregnancies where infants had documented sepsis, meningitis, or a major congenital anomaly. Neonatal outcomes were compared between women receiving (n = 1538) and not receiving epidural analgesia (n = 363) in the absence of intrapartum temperature elevation (≤99.5°F) and according to the level of intrapartum temperature elevation within the group receiving epidural (n = 2784). Logistic regression was used to evaluate neonatal outcome while controlling for confounders.

RESULTS

Maternal temperature >100.4°F developed during labor in 19.2% (535/2784) of women receiving epidural compared with 2.4% (10/425) not receiving epidural. In the absence of intrapartum temperature elevation (≤99.5°F), no significant differences were observed in adverse neonatal outcomes between women receiving and not receiving epidural. Among women receiving epidural, a significant linear trend was observed between maximum maternal temperature and all neonatal outcomes examined including hypotonia, assisted ventilation, 1- and 5-min Apgar scores <7, and early-onset seizures. In regression analyses, infants born to women with fever >101°F had a two- to sixfold increased risk of all adverse outcomes examined.

CONCLUSIONS

The proportion of infants experiencing adverse outcomes increased with the degree of epidural-related maternal temperature elevation. Epidural use without temperature elevation was not associated with any of the adverse outcomes we studied.

Bilateral middle cerebral artery thromboembolic occlusion. Could maternal hyperthermia be a detrimental factor?

We describe a six-month-old girl with microcephaly, developmental delay, truncal hypotonia, left pyramidal signs, partial seizures and myoclonic spasms, born to a feverish mother. MRI showed bilateral vascular lesions in the territory of the middle cerebral arteries, prevalent in the right hemisphere, together with hypoplasia of the posterior part of the corpus callosum and Wallerian degeneration of the cerebral peduncle. There may be many reasons for these lesions. In the reported patient the presence of maternal hyperthermia could have exacerbated cerebral thromboembolic occlusion.

Maternal obesity and neonatal Apgar scores

OBJECTIVE

To determine whether maternal obesity in early pregnancy is associated with low neonatal 5-min Apgar scores while adjusting for confounders.

METHODS

Data were obtained from Maine State Birth Records Database. Analyses were restricted to information on 58,089 white women and their newborns. Maternal weight status was defined using the recorded early second trimester maternal body mass index (BMI) and defined as normal weight (BMI <25), overweight (BMI 25 to <30), obese (BMI 30 to <40), and morbidly obese (BMI >or=40). Logistic regression analysis was used to assess the association of maternal weight status with low Apgar score while adjusting for confounders.

RESULTS

Compared with newborns of normal weight women, the risk to receive low Apgar scores (4-6) is increased in newborns of obese (OR 1.4, 95% CI 1.1-1.7) and morbidly obese mothers (OR 2.0, 95% CI 1.5-2.7). The association did not achieve significance for newborns of overweight mothers (OR 1.2, 95% CI 0.99-1.4). No association was identified between maternal weight status and very low Apgar scores (0-3).

CONCLUSIONS

Maternal obesity is associated with a significantly increased risk for decreased Apgar scores at birth. Further studies are needed to clarify the relationships among maternal obesity, complications of pregnancy, and neonatal outcome.

Temperature management in the delivery room

After being in a relatively stable thermoneutral uterus for the whole of pregnancy, the newborn baby enters a cooling environment and might suffer significant heat loss and hypothermia in the first minutes of life. Alternatively, the fetus might face significant hyperthermia during and immediately after delivery if the mother is febrile. Hypothermia, particularly in preterm babies, is associated with increased morbidity and mortality. Hyperthermic babies have a worse short-term outcome, and hyperthermia can be particularly detrimental in association with intrapartum asphyxia and infection. Prevention and treatment of these variations in temperature are still developing and the efficacy of some strategies remains unclear. Nevertheless, one goal in the delivery room is to maintain the newborn baby's temperature within the physiologically optimum range.

Risk factors for maternal intrapartum fever and short-term neonatal outcome

Our objective was to determine maternal risk factors for developing intrapartum fever during term labor and to evaluate perinatal outcomes for infants exposed to mothers with fever. We performed a retrospective cohort study of 330 mothers and their infants and 330 controls in a single institution. Prolonged labor, nulliparity, maternal disease, and prolonged membrane rupture were found to be the most significant predictors for developing intrapartum fever. Caesarean section and instrumental delivery were more commonly performed. Bacteriuria was present in 10 % of the mothers. Babies born to mothers with fever were more likely to have meconium-stained amniotic fluid. More babies in this group were symptomatic (mostly dyspnea) on admission. No cases of neonatal infection were recorded, and no severe morbidity or mortality was present. We concluded that in low-risk asymptomatic intrapartum fever, infection is the least common explanation. Perinatal outcomes may be influenced by medical decisions due to fever onset, such as delivery mode. Short-term outcomes are favorable.

Hyperthermia in the delivery: potential impact on neonatal mortality and morbidity

In recent years, it has become apparent that temperature can modify the extent of hypoxic-ischemic brain injury. There is an increasing body of experimental and clinical data showing a reduction in the extent of brain injury after intrapartum hypoxia-ischemia with induced hypothermia. Conversely, there is experimental evidence indicating a worsening of cerebral injury during or after ischemia under conditions of elevations in temperature in a variety of animal species. Neonatal experimental studies are limited, and the data are conflicting. This article addresses the available evidence concerning the potential impact of hyperthermia in the delivery on neonatal mortality and morbidity.

Depression at birth in term infants exposed to maternal chorioamnionitis: does neonatal fever play a role?

OBJECTIVES

(1) To determine the incidence and the time course of elevated temperature following delivery in term infants with clinical chorioamnionitis (CHORIO) and (2) to determine if the extent of temperature elevation at birth is associated with increased likelihood of NICU Admissions, birth depression, or with short-term neurological abnormalities.

DESIGN/METHODS

The infants were divided into two groups based on the median admission rectal temperature of 37.8 degrees C for the cohort. Depression at birth was defined as either the need of positive pressure ventilation for >2 minutes, intubation, or Apgar score <6 at 5 minutes. Neurological examination and assessment of encephalopathy (Sarnat staging) was performed at birth and daily thereafter, by one investigator blinded to temperature findings.

RESULTS

Infants with higher rectal temperature at 30 minutes of life were more likely to be admitted to NICU: OR (2.8, 95% confidence interval (CI) [1.8 to 4.3]), and were more likely to have birth depression OR (3, 95% CI [1.4 to 6.5]). For infants in NICU, a rectal temperature above 37.8 degrees C was present in 87% in the delivery room, persisted in 47% at 30 minutes, and declined to a normal temperature at 60 minutes of life in the absence of medical interventions. There was no relationship between neurological scores and neonatal temperature.

CONCLUSIONS

Term infants exposed to CHORIO who had a higher neonatal temperature at 30 minutes of life, were more likely to be admitted to the NICU and to have birth depression, than infants with lesser degree of temperature elevation after birth. Within the NICU group, the extent of temperature elevation was not associated with worse neurological outcomes.

Maternal Temperature Monitoring During Labor: Concordance and Variability Among Monitoring Sites

OBJECTIVE

Elevated maternal temperature in labor is associated with adverse immediate and long-term neonatal outcomes. Conventional methods of temperature measurement may not reflect the intrauterine temperature, which constitutes the fetal environment. The purpose of this study was to ascertain the most reliable noninvasive method of temperature monitoring in labor that would best reflect changes in intrauterine temperature.

METHODS

Women in labor receiving epidural analgesia had temperature readings taken every 10 seconds from the uterine cavity, ear canal, and skin surface of the leg and abdomen and hourly from the mouth.

RESULTS

Eighteen patients were studied for a mean of 228 minutes (range 56-464 minutes). The best indicator of intrauterine temperature was oral temperature, with a mean intraclass correlation coefficient of 0.6 (95% confidence interval 0.42, 0.77). On average, oral temperature underestimated intrauterine temperature by 0.8 degrees C (95% confidence interval 0.7 degrees C, 1 degrees C). Allowing for this, oral temperature greater than 37.2 degrees C detected an intrauterine temperature greater than 38 degrees C with a sensitivity of 81% and a specificity of 96%. The intraclass correlation coefficients of all other sites with intrauterine temperature were poor (0.1 or less). As expected, the temperature at all sites increased as labor progressed.

CONCLUSION

Oral temperature, measured carefully, has an acceptable correlation with intrauterine temperature and is recommended for routine detection of maternal pyrexia in labor. Continuous skin and external auditory canal temperature measurements did not correlate well.

LEVEL OF EVIDENCE

II-3

Induced hyperthermia exacerbates neurologic neuronal histologic damage after asphyxial cardiac arrest in rats

BACKGROUND

Temperature is an important modulator of the evolution of ischemic brain injury--with hypothermia lessening and hyperthermia exacerbating damage. We recently reported that children resuscitated from predominantly asphyxial arrest often develop an initial spontaneous hypothermia followed by delayed hyperthermia. The initial hypothermia observed in these children was frequently treated with warming lights which, despite careful monitoring, often resulted in overshoot hyperthermia. We have previously reported in a rat model of asphyxial cardiac arrest that active warming, to prevent spontaneous hypothermia, worsens brain injury.

OBJECTIVE

We sought to determine whether delayed induction of hyperthermia would worsen brain injury after asphyxial arrest in rats.

DESIGN

Male Sprague-Dawley rats were asphyxiated for 8 mins and resuscitated. An implantable temperature probe was placed into the peritoneum before asphyxia. The probe is a component of a computer-based, radiofrequency, telemetry system (Minimitter, Sunriver, OR) that allowed continuous acquisition and manipulation (via heating and cooling devices) of core (intraperitoneal) body temperature. Body temperature was monitored but not manipulated for the first 24 hrs of recovery. Rats were assigned to: no temperature manipulation (n = 21), induced hyperthermia (40 +/- 0.5 degrees C) for 3 hrs beginning at 24 hrs (n = 21), or induced hyperthermia at 48 hrs (n = 10). Control groups included sham rats (all surgical procedures except asphyxia) treated with induced hyperthermia at 24 hrs (n = 4) or 48 hrs (n = 4) and naïve rats (n = 4). Rats were killed at 7 days and injured neurons in hematoxylin and eosin stained coronal brain sections through dorsal hippocampus were scored in a semiquantitative manner on a scale of 0 to 10 (0 = normal; 1 = up to 10% neurons with ischemic neuronal changes; 10 = 90-100% neurons with ischemic neuronal changes). Normal-appearing neurons were also counted in CA1. The number of normal-appearing neurons in a 20x field in CA1 were also counted.

MAIN RESULTS

All naïve and sham hyperthermia control rats survived the protocol. There was a trend toward a larger mortality rate in asphyxiated rats treated with induced hyperthermia at 24 hrs (9 of 21 died) vs. asphyxiated rats without induced hyperthermia (3 of 21) or with hyperthermia induced at 48 hrs (3 of 10) (Kaplan-Meier p=.0595). Asphyxiated rats with hyperthermia induced at 24 hrs had larger (worse) histopathology damage scores than rats subjected to asphyxia without induced hyperthermia (9.3 +/- 1.5 vs. 6.2 +/- 2.6; p=.001). Histopathology damage scores in asphyxiated rats with hyperthermia induced at 48 hrs did not differ from those in rats asphyxiated without induced hyperthermia (6.4 +/- 3.0 vs. 6.2 +/- 2.6; p=.907). There were fewer normal-appearing CA1 neurons in asphyxiated rats with hyperthermia induced at 24 hrs vs. rats subjected to asphyxia without induced hyperthermia (33 +/- 13 vs. 67 +/- 36; p=.002). The number of normal-appearing CA1 neurons in asphyxiated rats with hyperthermia induced at 48 hrs did not differ from that in rats asphyxiated without induced hyperthermia (59 +/- 21 vs. 67 +/- 36; p=.885).

CONCLUSIONS

Induced hyperthermia when administered at 24 hrs, but not 48 hrs, worsens ischemic brain injury in rats resuscitated from asphyxial cardiac arrest. This may have implications for postresuscitative management of children and adults resuscitated from cardiac arrest. The common clinical practice of actively warming patients with spontaneous hypothermia might result in iatrogenic injury if warming results in hyperthermic overshoot. Avoidance of hyperthermia induced by active warming at critical time periods after cardiac arrest may be important.

Chorioamnionitis and brain injury

The limited available evidence supports a strong association of chorioamnionitis with neonatal encephalopathy and CP in the term infant. The association of chorioamnionitis with depressed Apgar scores or neonatal seizures and with CP is equivocal in the preterm infant. Different study results may be related to differences in study populations, perhaps specifically to differences in susceptibility by stages of neurologic development as well as differences in gene frequencies associated with inflammation and thrombophilia. We require further understanding of the normal roles of cytokines in brain development, pregnancy, and inflammatory homeostasis before clinical interventions directed at cytokines, their receptors, or the inflammatory process are considered.

The epidemiology of cerebral palsy in term infants

Half of cerebral palsy (CP) arises in infants of normal birthweight; yet, many fewer studies seek to identify risk factors for CP in term and near-term infants than in those born very prematurely. There has been no net decrease in the prevalence of CP in term and near-term infants over recent decades. Potentially asphyxiating birth complications account for a small minority of CP cases. Recent studies suggest that disorders of coagulation and intrauterine exposure to infection or inflammation are associated with risk of CP, and that both can be accompanied by signs of neonatal encephalopathy, the best available predictor of CP in term neonates. Therapeutic interventions directed at preventing interruption of oxygen supply have not been shown to reduce the occurrence of CP. There have not yet been studies examining whether medical interventions directed at infection or coagulation disorder can reduce the frequency of CP.

Fever in labour and neonatal encephalopathy: a prospective cohort study

OBJECTIVE

To determine whether the reported association of maternal fever with neonatal encephalopathy is independent of other associated intrapartum risk factors.

DESIGN

Prospective cohort study.

SETTING

Dublin teaching hospital delivery ward.

POPULATION

4,915 low risk women in labour at 36-41 weeks of gestation.

METHODS

Using logistic regression with odds ratios and 95% confidence intervals, the incidence of neonatal encephalopathy and other neonatal outcomes of women who had an intrapartum fever >37.5 degrees C was compared with those who did not.

RESULTS

The cohort comprised 33% of all deliveries during the study period. Neonatal encephalopathy was diagnosed in 3.25/1,000 births. The incidence of intrapartum fever was 6.8%. Maternal fever was strongly associated with neonatal encephalopathy (crude OR 10.8, 95% CI 4.0-29.3). Univariate analysis showed maternal fever was associated with epidural analgesia, nulliparity, induction, longer labour, oxytocin administration, greater fetal birthweight and gestational age and instrumental vaginal delivery, but not with prolonged (>24hours) prelabour rupture of the membranes. The association of fever with neonatal encephalopathy persisted having adjusting for these covariates (adjusted OR 4.72, 95% CI 1.28-17.4).

CONCLUSIONS

The relationship between maternal intrapartum fever and neonatal encephalopathy is independent of other known intrapartum risk factors. This provides further evidence for the role of inflammatory processes in the aetiology of neonatal neurological morbidity.

Is temperature important in delivery room resuscitation?

The possibility that temperature may affect the outcome of resuscitation from severe perinatal asphyxia has been a long-standing focus of research. Experimentally it is now well established that even small changes in temperature during severe hypoxia-ischemia critically modulate outcome. Clinical and experimental studies have now shown that hypoxic-ischemic injury continues to evolve after resuscitation. Experimentally, prolonged mild to moderate hypothermia can dramatically reduce this delayed injury, while mild hyperthermia over the same period worsens injury. Indeed there are data indicating that moderate post-ischemic hyperthermia can be deleterious as late as 24 h after reperfusion. Hypothermia has significant potential adverse effects, and at present its clinical use is restricted to large randomized controlled trials. The present paper reviews evidence suggesting that both primary prevention of maternal pyrexia during labour, and secondary prevention of hyperthermia after neonatal resuscitation, have the potential to significantly reduce the consequences of perinatal hypoxia-ischemia.

International Guidelines for Neonatal Resuscitation: An excerpt from the Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care: International Consensus on Science. Contributors and Reviewers for the Neonatal Resuscitation Guidelines

The International Guidelines 2000 Conference on Cardiopulmonary Resuscitation (CPR) and Emergency Cardiac Care (ECC) formulated new evidenced-based recommendations for neonatal resuscitation. These guidelines comprehensively update the last recommendations, published in 1992 after the Fifth National Conference on CPR and ECC. As a result of the evidence evaluation process, significant changes occurred in the recommended management routines for: * Meconium-stained amniotic fluid: If the newly born infant has absent or depressed respirations, heart rate <100 beats per minute (bpm), or poor muscle tone, direct tracheal suctioning should be performed to remove meconium from the airway. * Preventing heat loss: Hyperthermia should be avoided. * Oxygenation and ventilation: 100% oxygen is recommended for assisted ventilation; however, if supplemental oxygen is unavailable, positive-pressure ventilation should be initiated with room air. The laryngeal mask airway may serve as an effective alternative for establishing an airway if bag-mask ventilation is ineffective or attempts at intubation have failed. Exhaled CO(2) detection can be useful in the secondary confirmation of endotracheal intubation. * Chest compressions: Compressions should be administered if the heart rate is absent or remains <60 bpm despite adequate assisted ventilation for 30 seconds. The 2-thumb, encircling-hands method of chest compression is preferred, with a depth of compression one third the anterior-posterior diameter of the chest and sufficient to generate a palpable pulse. * Medications, volume expansion, and vascular access: Epinephrine in a dose of 0.01-0.03 mg/kg (0.1-0.3 mL/kg of 1:10,000 solution) should be administered if the heart rate remains <60 bpm after a minimum of 30 seconds of adequate ventilation and chest compressions. Emergency volume expansion may be accomplished with an isotonic crystalloid solution or O-negative red blood cells; albumin-containing solutions are no longer the fluid of choice for initial volume expansion. Intraosseous access can serve as an alternative route for medications/volume expansion if umbilical or other direct venous access is not readily available. * Noninitiation and discontinuation of resuscitation: There are circumstances (relating to gestational age, birth weight, known underlying condition, lack of response to interventions) in which noninitiation or discontinuation of resuscitation in the delivery room may be appropriate.

Infection, inflammation and the risk of cerebral palsy

The balance of current evidence indicates that intrauterine exposure to infection and inflammation contributes to the risk of cerebral palsy. The mechanisms involved are not well understood and may differ in very immature versus term infants. Term infants exposed to maternal infection are predisposed to delivery room depression and neonatal encephalopathy.