The Dublin randomized controlled trial of intrapartum fetal heart rate monitoring

Early-onset neonatal seizures: types, risk factors and short-term outcome

In a large majority of term newborns, early-onset neonatal seizures (EONS) are believed to relate to perinatal risk factors.

AIM

To identify risk factors for EONS.

METHODS

Among a cohort of 1293 newborns admitted over a period of 2 years to the neonatal intensive care unit of Tikur Anbasa Hospital, Addis Ababa, 93 had seizures. The case control study method was used to identify risk factors associated with EONS. Univariate analysis was used to further examine risk factors after adjusting for the effect of severe perinatal asphyxia (Apgar < or = 3).

RESULTS

A total of 78 (85%) term newborns had EONS. Hypoxic-ischaemic encephalopathy (OR 3.46, 95% CI 2.74-7.42) and shock (OR 2.53, 95% CI 1.51-4.76) were significantly associated with EONS. Multifocal clonic (66%) followed by focal clonic (22%) were the most common types of EONS. Nine (11%) of the newborns with EONS died. During follow-up, 37 (53%) of the 69 surviving newborns with EONS had psychomotor delay with or without neurological deficit.

CONCLUSION

Hypoxic-ischaemic encephalopathy and shock are important causes of EONS.

Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour

BACKGROUND

Cardiotocography (sometimes known as electronic fetal monitoring), records changes in the fetal heart rate and their temporal relationship to uterine contractions. The aim is to identify babies who may be short of oxygen (hypoxic), so additional assessments of fetal well-being may be used, or the baby delivered by caesarean section or instrumental vaginal birth.

OBJECTIVES

To evaluate the effectiveness of continuous cardiotocography during labour.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (March 2006), CENTRAL (The Cochrane Library 2005, Issue 4), MEDLINE (1966 to December 2005), EMBASE (1974 to December 2005), Dissertation Abstracts (1980 to December 2005) and the National Research Register (December 2005).

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials involving a comparison of continuous cardiotocography (with and without fetal blood sampling) with (a) no fetal monitoring, (b) intermittent auscultation (c) intermittent cardiotocography.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed eligibility, quality and extracted data.

MAIN RESULTS

Twelve trials were included (over 37,000 women); only two were high quality. Compared to intermittent auscultation, continuous cardiotocography showed no significant difference in overall perinatal death rate (relative risk (RR) 0.85, 95% confidence interval (CI) 0.59 to 1.23, n = 33,513, 11 trials), but was associated with a halving of neonatal seizures (RR 0.50, 95% CI 0.31 to 0.80, n = 32,386, nine trials) although no significant difference was detected in cerebral palsy (RR 1.74, 95% CI 0.97 to 3.11, n = 13,252, two trials). There was a significant increase in caesarean sections associated with continuous cardiotocography (RR 1.66, 95% CI 1.30 to 2.13, n =18,761, 10 trials). Women were also more likely to have an instrumental vaginal birth (RR 1.16, 95% CI 1.01 to 1.32, n = 18,151, nine trials). Data for subgroups of low-risk, high-risk, preterm pregnancies and high quality trials were consistent with overall results. Access to fetal blood sampling did not appear to influence the difference in neonatal seizures nor any other prespecified outcome.

AUTHORS' CONCLUSIONS

Continuous cardiotocography during labour is associated with a reduction in neonatal seizures, but no significant differences in cerebral palsy, infant mortality or other standard measures of neonatal well-being. However, continuous cardiotocography was associated with an increase in caesarean sections and instrumental vaginal births. The real challenge is how best to convey this uncertainty to women to enable them to make an informed choice without compromising the normality of labour.

Rates of neonatal death and cerebral palsy associated with fetal growth restriction among very low birthweight infants. A temporal analysis

OBJECTIVE

To assess whether changes over time in neonatal survival and infants' neurodevelopmental outcome among very low birthweight (VLBW) infants was correlated with the obstetric aetiology of VLBW.

DESIGN

A cohort study of 773 VLBW infants.

SETTING

A University hospital in Northern Italy.

POPULATION

All the VLBW infants born over a 20-year period (1983-2002) at a single institution.

METHODS

Evaluation of neonatal mortality and neurodevelopmental outcome of the surviving infants at 2 years of corrected age. Logistic regression analysis was used to compare the improvements of neonatal outcome associated with obstetric risk factors over time.

MAIN OUTCOME MEASURES

The risk reduction of neonatal death or cerebral palsy associated with each obstetric category responsible for VLBW over time.

RESULTS

The overall rates of neonatal mortality and cerebral palsy were 38.7% (43/111) and 17% (9/53) in the period 1983-87 and 13.7% (34/24) and 6.3% (13/205) in the period 1998-2002, respectively. The adjusted decrement per 5-year period was 33.1% (95% CI = 7.9-51.4) for neonatal death and 29.1% (95% CI = 25.3-32.7) for cerebral palsy, respectively. The adjusted rise in the rate of intact survival at 2 years of corrected age was 7.6% (95% CI = 3.1-12.3) per quinquennium. In logistic models with neonatal death or cerebral palsy as a combined outcome variable, and gestational age, corticosteroid use, surfactant use, and time of birth as explanatory variables, fetal growth restriction (P < 0.001) and pre-eclampsia (P= 0.011) interacted significantly with period of birth. The adjusted decrement in the rate of neonatal death or cerebral palsy as a combined variable was 27.5% per 5 years (95% CI = 13-39.6) in the overall population, 54.5% per 5 years (95% CI = 46.8-61.2) (P < 0.001 compared with overall population) among growth-restricted infants and 50.3% per 5 years (95% CI = 42.5-57.1) (P= 0.003 compared with overall population) in infants born to mothers with pre-eclampsia.

CONCLUSIONS

Over a period of 20 years, the decrement in the rate of neonatal death or cerebral palsy was higher in growth-restricted fetuses than in other VLBW infants. This reduction was not obtained at the expense of an increased rate of neurodevelopmental impairments in surviving infants.

Predicting the risk of metabolic acidosis for newborns based on fetal heart rate signal classification using support vector machines

Cardiotocography is the main method used for fetal assessment in every day clinical practice for the last 30 years. Many attempts have been made to increase the effectiveness of the evaluation of cardiotocographic recordings and minimize the variations of their interpretation utilizing technological advances. This research work proposes and focuses on an advanced method able to identify fetuses compromised and suspicious of developing metabolic acidosis. The core of the proposed method is the introduction of a support vector machine to "foresee" undesirable and risky situations for the fetus, based on features extracted from the fetal heart rate signal at the time and frequency domains along with some morphological features. This method has been tested successfully on a data set of intrapartum recordings, achieving better and balanced overall performance compared to other classification methods, constituting, therefore, a promising new automatic methodology for the prediction of metabolic acidosis.

Developing a tool to appraise fetal monitoring guidelines for women at low obstetric risk

AIM

The aim of this paper is to report the development and use of a tool to appraise guidelines for fetal heart rate monitoring and discuss the findings generated in the appraisal process.

BACKGROUND

Expert guidance on the appropriate method of monitoring the fetal heart in labour has been available for some time. However, practices not based on evidence were continuing routinely in the United Kingdom.

METHODS

We produced an 18-item tool for the appraisal of guidelines. Heads of Midwifery Services were asked to send the guideline currently in use. Twenty-four out of 28 responded, and sent 32 guidelines. Pairs of multidisciplinary reviewers appraised each guideline.

RESULTS

A prevalidated generic appraisal instrument was not found to be appropriate for intrapartum fetal monitoring guidelines. When using our own specifically-developed appraisal tool for assessing the quality of fetal monitoring guidelines, only 11 reviewer pairs showed 'good' or 'moderate' agreement in their scores.

CONCLUSIONS

Generically-validated guidelines may not be sufficiently discriminatory for specialized areas of practice such as intrapartum fetal monitoring.

Fetal pulse oximetry and neonatal outcome: a study in a developing country

BACKGROUND

The aim of this cohort, prospective study was to compare the diagnostic value of intrapartum fetal pulse oximetry (FPO) with that of fetal scalp blood gas (FSBG) for an abnormal neonatal outcome in cases with abnormal fetal heart rate (FHR) tracings.

METHODS

Fetal oxygen saturation was continuously monitored with Nellcor N-400 FPO during labor. Simultaneous FSBG determinations were obtained. The results were analyzed in relation to umbilical arterial cord blood pH and neonatal outcome. Studied FPO cutoff levels were 30 and 40% hemoglobin saturation and that of FSBG pH was 7.2.

RESULTS

During the study, there were 9825 deliveries; 415 had abnormal FHR. Only 150 fulfilled the whole screening panel. When the outcome variable was umbilical arterial pH, the positive predictive values of the three methods (FPO30, FPO40, FSBG) were 57, 61 and 65% and the negative predictive values were 43, 39 and 35% respectively. The sensitivity of FPO30 was highest (75%). Considering abnormal neonatal outcome, again the sensitivity was also highest for FPO30 (89%). The sensitivity of FSBG was 82%. The specificity of the three methods were 53, 49 and 38% respectively.

CONCLUSION

The diagnostic value of intrapartum FPO compares favorably with FSBG. FPO seems to be a reliable and less invasive tool and may decrease unnecessary interventions and unnecessary fetal scalp blood sampling in cases of suspected fetal distress. The FPO cutoff of 30% saturation defined by previous studies appears to be appropriate.

Amnioinfusion for the prevention of the meconium aspiration syndrome

BACKGROUND

It is uncertain whether amnioinfusion (infusion of saline into the amniotic cavity) in women who have thick meconium staining of the amniotic fluid reduces the risk of perinatal death, moderate or severe meconium aspiration syndrome, or both.

METHODS

We performed a multicenter trial in which 1998 pregnant women in labor at 36 or more weeks of gestation who had thick meconium staining of the amniotic fluid were stratified according to the presence or absence of variable decelerations in fetal heart rate and then randomly assigned to amnioinfusion or to standard care. The composite primary outcome measure was perinatal death, moderate or severe meconium aspiration syndrome, or both.

RESULTS

Perinatal death, moderate or severe meconium aspiration syndrome, or both occurred in 44 infants (4.5 percent) of women in the amnioinfusion group and 35 infants (3.5 percent) of women in the control group (relative risk, 1.26; 95 percent confidence interval, 0.82 to 1.95). Five perinatal deaths occurred in the amnioinfusion group and five in the control group. The rate of cesarean delivery was 31.8 percent in the amnioinfusion group and 29.0 percent in the control group (relative risk, 1.10; 95 percent confidence interval, 0.96 to 1.25).

CONCLUSIONS

For women in labor who have thick meconium staining of the amniotic fluid, amnioinfusion did not reduce the risk of moderate or severe meconium aspiration syndrome, perinatal death, or other major maternal or neonatal disorders.

A survey of regional guidelines for intrapartum electronic fetal monitoring in women at low obstetric risk

AIM

to determine whether intrapartum fetal monitoring guidelines used by midwives in one region of England for women at low risk of obstetric complications were evidence-based.

OBJECTIVE

to assess the quality of such guidelines using an appraisal tool.

DESIGN AND SETTING

an appraisal of guidelines gained via a postal survey of all National Health Service Trusts supplying maternity services in one region in the north of England, conducted over a six-week period (June-July 2001).

PARTICIPANTS

28 Trusts were eligible to participate; 32 guidelines were returned from 24 Trusts.

DATA ANALYSIS

two reviewers from a multi-disciplinary panel appraised each guideline, producing two sets of data that were analysed independently of each other. Each was treated as a separate case (n=64 cases). Inter-reviewer agreement was summarised using descriptive categories.

FINDINGS

the highest possible overall quality score was 54, and the lowest 18. Whilst no guideline scored 54, five of the 64 cases scored 18. The mean overall quality score was 26.8. In 36 of the 64 cases, both reviewers rated guidelines as 'definitely not' recommended for practice. Guidelines were scored against specific aspects of evidence-based practice. Forty-one of the 64 cases received the lowest possible quality score (='1') for use of systematic reviews of the literature on electronic fetal monitoring. In 47 cases, guidelines were scored '1' for the quality of evidence-based clinical recommendations. The quality of information on client monitoring preferences was considered low in over half the 64 cases (n=35). There were no instances where the number of cases receiving 'highest possible quality' scores was greater than those receiving 'lowest possible quality' ratings.

CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

a small number of guidelines were assessed as high quality, but the majority were poorly appraised by the reviewer group in most areas. This has implications for the delivery of evidence-based midwifery care since those midwives practising according to the guidelines surveyed would not have been supported in implementing research into practice.

A short history of evidence-based obstetric care

Evidence-based obstetric care is a relatively new concept, which had its origins in the early 1970s when Iain Chalmers and his colleagues in Oxford responded to the statement of Archie Cochrane that much of the evidence underpinning obstetric (and other) practices was flawed. They recognized the importance of the quality of evidence in informing clinical decision making, particularly evidence from randomized trials. This was a shift away from opinion-based obstetrics, which up until then had been the dominant paradigm. Since then, there has been an exponential increase in the number and quality of clinical trials in obstetrics, and with their dissemination through the Cochrane database of systematic reviews, there have been many improvements in obstetric practice, more closely aligning it with sound evidence.

Patient controlled analgesia for labour: a comparison of remifentanil with pethidine

We compared the analgesic efficacy and safety of remifentanil and pethidine via patient controlled analgesia for women in established uncomplicated labour. Women received either remifentanil 40 microg with a 2-min lockout (n = 20) or pethidine 15 mg with a 10-min lockout (n = 19). Visual analogue scores for pain during the study and for overall pain were similar for both groups (mean (SD) 6.4 (1.5) cm for remifentanil and 6.9 (1.7) cm for pethidine). The area under the curve for visual analogue scores of satisfaction with analgesia was higher for remifentanil than for pethidine (p = 0.001). Maternal arterial oxygen saturation was similar in both groups. Neurologic and Adaptive Capacity Scores at 30 min were higher for remifentanil than for pethidine (median (interquartile range [range]) 36 (34.5-37 [32-39]) vs 34 (33-35 [30-35]), respectively; p = 0.003).

Intrapartum management of nonreassuring fetal heart rate patterns: a randomized controlled trial of fetal pulse oximetry

OBJECTIVE

We tested if fetal pulse oximetry in addition to electronic fetal monitoring (CTG) and scalp blood sampling improves the accuracy of fetal assessment and allows safe reduction of operative deliveries (-50%) and scalp blood sampling (-50%) performed because of nonreassuring fetal status. Study design A randomized controlled trial was conducted in 146 patients with term pregnancies in active labor and abnormal fetal heart rate patterns: 73 had electronic fetal heart rate monitoring (CTG) and fetal scalp blood sampling (control group), 73 had CTG, fetal scalp blood sampling, and continuous fetal pulse oximetry (study group).

RESULTS

There was a reduction of -50% in operative deliveries and fetal scalp blood sampling performed because of nonreassuring fetal status in the study group: operative deliveries, study versus control 25/49 (P </= .001); fetal scalp sampling, study versus control 32/64 (P </= .001). An increase in cesarean sections because of dystocia in the study group did not change the net number of operative deliveries. There was no difference between the 2 groups in adverse maternal or neonatal outcomes, as well as for the end points of metabolic acidosis and need for resuscitation.

CONCLUSION

There was a safe reduction in operative deliveries (-50%) and scalp blood sampling (-50%) performed because of nonreassuring fetal status. The increase in cesarean sections because of dystocia in the study group was a well-documented arrest of labor, but it did not change the total number of operative deliveries in this group.

Intrapartum fetal heart rate monitoring in cases of cytomegalovirus infection

OBJECTIVE

Several studies have shown that abnormal intrapartum fetal heart rate patterns are the results from pre-existing fetal brain damage. We evaluated intrapartum fetal heart rate pattern of cytomegalovirus-infected fetuses and correlated the patterns with neurologic outcomes.

STUDY DESIGN

Between 1991 and 2001, there were 20 cytomegalovirus-infected fetuses. We selected 40 fetuses as control subjects that were matched for gestational age and birth weight. Fetal heart rate was interpreted according to the guidelines of the National Institute for Child and Human Development. The incidence of abnormal fetal heart rate pattern and umbilical blood gases were compared between both groups. We also investigated the factors that contributed to abnormal fetal heart rate pattern in the cytomegalovirus group.

RESULTS

Nonreassuring fetal heart rate patterns (prolonged deceleration and recurrent late deceleration) were observed in 8 of 20 fetuses (prolonged deceleration, 7 fetuses; recurrent late deceleration, 1 fetus) in the cytomegalovirus group and in 3 of 41 fetuses (prolonged deceleration, 1 fetus; recurrent late deceleration, 2 fetuses) in the control group (P<.05, Fisher test). Baseline fetal heart rate variability was minimal in 4 of the 7 prolonged deceleration cases in the cytomegalovirus group. Umbilical pH <7.1 was found for 1 fetus in the cytomegalovirus group. The average umbilical arterial pH values were similar in both the groups. In the cytomegalovirus group, there were no differences in the incidence of contributing factors between 8 fetuses with abnormal fetal heart rate pattern (prolonged deceleration and recurrent late deceleration) and 8 fetuses with no change. There were 3 fetuses with cerebral palsy: 2 fetuses in the no change group and 1 fetus in the prolonged deceleration group. Antigenemia was positive exclusively in 4 cases with abnormal fetal heart rate pattern (P<.05).

CONCLUSION

Cytomegalovirus-infected fetuses are more likely to show abnormal intrapartum fetal heart rate patterns than low-risk control fetuses, which suggests that the perinatal detection of cytomegalovirus is necessary to distinguish hypoxic-ischemic encephalopathy.

Obstetric risk factors and persistent increases in brain parenchymal echogenicity in preterm infants

OBJECTIVE

To assess the risk of persistent (>7 days) increases in brain parenchymal echogenicity in preterm infants and their association with known obstetric risk factors.

DESIGN

Case-control study of prospectively collected data.

SETTING

A University hospital in Northern Italy.

POPULATION

Eighty-five singleton infants between 24 and 34 weeks of gestation with a cranial ultrasonographic diagnosis of persistently increased parenchymal echogenicity without development of cystic degeneration, and 170 control infants with negative cranial ultrasonographic findings.

METHODS

A comparison of the prevalence of selected obstetric risk factors between infants with persistent echo-dense lesions and negative controls.

MAIN OUTCOME MEASURES

Odds ratios of persistent echo-dense lesions including first-degree interactions between variables.

RESULTS

After adjusting for birthweight, logistic regression analysis showed that the only factor associated with an increased risk of persistent brain echo-dense lesions in infants was multiple courses of antenatal steroids (OR = 2.14, 95% CI = 1.11-4.15, P= 0.024). In this group, the risk of persistent echo-dense lesions was particularly high in: (i) mothers receiving dexamethasone rather than betamethasone (P value for interaction = 0.015) and (ii) after expectant management of pre-eclampsia or intrauterine growth retardation (P value for interaction = 0.03).

CONCLUSIONS

Multiple doses of antenatal steroids, especially dexamethasone, could influence the prevalence of persistent increases in brain parenchymal echogenicity in preterm infants.

The Scottish perinatal neuropathology study: clinicopathological correlation in early neonatal deaths

BACKGROUND

A proportion of neonatal deaths from asphyxia have been shown to be associated with pre-existing brain injury.

OBJECTIVES

(a) To compare the epidemiology of infants displaying signs of birth asphyxia with those not showing signs; (b) to examine the neuropathology and determine if possible the timing of brain insult comparing asphyxiated with non-asphyxiated infants; (c) to compare the clinical features of those born with birth asphyxia with and without pre-labour damage.

METHODS

Over a two year period, all 22 Scottish delivery units collected clinical details on early neonatal deaths. Requests for post mortem included separate requests for detailed neuropathological examination of the brain. Infants were classified into two groups: birth asphyxia and non-birth asphyxia. Clinicopathological correlation was used to attempt to define the time of brain insult.

RESULTS

Detailed clinical data were available on 137 of 174 early neonatal deaths that met the inclusion criteria. Seventy of 88 parents who had agreed to post mortem examination consented to a detailed examination of additional samples from the brain; in 53 of these cases the infant was born in an asphyxiated condition. All asphyxiated and encephalopathic infants, 38% of mature and 52% of preterm infants with features of birth asphyxia but without encephalopathy, and only one of 12 infants without any signs of birth asphyxia showed damage consistent with onset before the start of labour.

CONCLUSIONS

In a large proportion of neonatal deaths, brain injury predates the onset of labour. This is more common in infants born in an asphyxiated condition.

Singleton vaginal breech delivery at term: still a safe option

OBJECTIVE

To examine the obstetric and perinatal outcome of pregnancies with singleton breech presentation at term when selection for vaginal delivery was based on clear prelabor and intrapartum criteria.

METHODS

The outcomes of all pregnancies with a breech presentation after 37 weeks of gestation were retrospectively reviewed from January 1997 to June 2000. Criteria for prelabor cesarean or trial of vaginal breech delivery included type of breech, estimated fetal weight (more than 3,800 g), maternal preference, and gestation more than 41 weeks. An intrapartum protocol excluded induction and oxytocin augmentation of labor, combined with a low threshold for cesarean delivery for dystocic labor; an experienced obstetrician was in attendance during labor and delivery.

RESULTS

Of 641 women, 343 (54%) underwent prelabor cesarean, and 298 (46%) had a trial of vaginal delivery, of whom 146 (49%) delivered vaginally. Significantly fewer nulliparas (58 of 158, 37%) than multiparas (88 of 140, 63%; P <.001) achieved vaginal delivery after trial of labor. Significantly more infants weighing more than 3,800 g were selected for prelabor (87 of 343, 25%) and intrapartum (31 of 152, 20%) cesarean than delivered vaginally (15 of 146, 10%). Two neonates (0.7%) had Apgar scores of less than 7 at 5 minutes; both were neurologically normal at 6 weeks. There were no nonanomalous perinatal deaths and no cases of significant trauma or neurological dysfunction; 3 infants delivered vaginally died due to lethal anomalies.

CONCLUSION

Safe vaginal breech delivery at term can be achieved with strict selection criteria, adherence to a careful intrapartum protocol, and with an experienced obstetrician in attendance. Our protocol effectively selects larger infants for cesarean delivery.

LEVEL OF EVIDENCE

II-2

Unselected low-risk pregnancies and the effect of continuous intrapartum fetal heart rate monitoring on umbilical blood gases and cerebral palsy

OBJECTIVE

Our purpose was to evaluate the clinical validity of electronic fetal heart rate monitoring to detect fetal acidemia and to evaluate the prevalence of cerebral palsy in unselected low-risk pregnancies.

STUDY DESIGN

We selected two secondary and two tertiary level institutions in which 10,030 infants were born. Among them, 5546 of the pregnancies were low-risk pregnancies by antepartum evaluation. The fetal heart rate patterns were interpreted according to the guidelines of the National Institute of Child Health and Human Development. The correlations between the fetal heart rate pattern and umbilical blood gases and the fetal heart rate pattern and cerebral palsy were studied. Spastic cerebral palsy was diagnosed at > or =1 year by pediatric neurologists. Statistics included unpaired t test, contingency table with chi(2) and Fisher tests, and one-way analysis of variance with Bonferroni/Dunn test.

RESULTS

On the basis of the severity of decelerations, frequency of decelerations, and decreased variability, umbilical pH, and Po(2) level were decreased accordingly, and incidence of pH<7.1 was increased. Sensitivity and false-positive rate of nonreassuring fetal heart rate patterns for fetal acidemia were 63% and 89%. There were nine cerebral palsy cases: six of the cases were preexisting asphyxia before monitoring was initiated, two of the cases were cytomegaloviral infections, and one of the cases was a maternal amniotic fluid embolism.

CONCLUSION

In low-risk pregnancies, intrapartum fetal heart rate monitoring was useful to detect fetal acidemia. Cerebral palsy caused by intrapartum asphyxia was restricted to unavoidable accidents under continuous fetal heart rate monitoring.

Intrapartum fetal pulse oximetry and fetal heart rate decelerations

OBJECTIVES

To determine the behavior of fetal oxygenation (FSpO(2)) in different patterns of fetal heart rate decelerations (FHR).

METHODS

A total of 787 decelerations were studied.

RESULTS

FSpO(2) decreased significantly during decelerations, especially when the alteration was prolonged.

CONCLUSIONS

Modifications in FHR occur simultaneously with alterations in FSpO(2), although the latter do not persist in time. Different degrees of FSpO(2) seen prior to deceleration are an expression of fetal respiratory status.

Etiology of cerebral palsy

Cerebral palsy has a complex and multifactorial etiology. Approximately 5%-10% of cases can be ascribed to perinatal hypoxia, but the vast majority of cases are caused by the interplay of several risk factors and antenatal, perinatal, and neonatal events. The strongest risk factors include prematurity and low birth weight. The prevalence of cerebral palsy has remained constant despite improvements in obstetric and neonatal care. For a long time, the only causal factors explored to account for risk for cerebral palsy were complications of labor and delivery. As other periods have been investigated, new associations have come to light. The current understanding of contributors to the risk for cerebral palsy is still incomplete. Multiple causes may interact by way of excitotoxic, oxidative, or other converging pathophysiologic pathways. A single factor, unless present to an overwhelming degree, often may be insufficient to produce cerebral damage, whereas two or three interacting pathogenic assaults may overwhelm natural defenses and produce irreversible brain injury. The low prevalence of cerebral palsy makes the formal testing of preventative strategies difficult. There is a need for such strategies to be carefully assessed in well designed, multicenter, randomized, controlled trials before becoming part of clinical practice, however, so that the balance between harm and benefit is known in advance.

Utilisation en routine de l’analyse du segment ST de l’électrocardiogramme fœtal pour la surveillance du travail. Une année d’expérience (résultats préliminaires)

OBJECTIVES

Two randomized trials found that monitoring labor by analyzing the fetal electrocardiogram (STAN) appears to offer better sensitivity and specificity in screening for metabolic acidosis than cardiotocography (CTG) does. We report here the results of a descriptive study of 173 cases between 1 June 2001 and 31 May 2002, the objectives of which were twofold: to determine the number of possible false negatives (defined by neonatal metabolic acidosis with a pH less than 7.05 and base deficit (BD) greater than 12 mmol/l, in the absence of a STAN decisions event more than 30 min before birth), and to assess whether STAN indicated the need for operative intervention too late in cases of fetal distress.

PATIENTS AND METHODS

Our study was conducted on an at-risk population with CTG changes. STAN was used with a scalp electrode to monitor labor according to a protocol based upon the FIGO CTG classification and the clinical instructions used in the Swedish trial. Accordingly, we compared two groups: in group 1, a STAN decision event required a rapid conclusion to labor, while in group 2, the absence of any STAN decision event meant that labor continued, despite the changes in the tracing.

RESULTS

We found seven cases with a neonatal pH less than 7.05, but only one may involve a false negative by this method. The mean arterial pH and the number of fetuses born with an arterial pH less than 7.10 did not differ significantly between the two groups, nor were there any significant differences in the mean BD at birth, or the number of children with a BD greater than 12 mmol/l.

CONCLUSION

The results appear to indicate that use of STAN with the usual CTG enables an appropriate response to cases of fetal distress, but it remains difficult to determine the real benefits that can be expected from this method in France. Longer assessment in our population is required before we can assess its actual advantages.

Doppler flow velocity to measure the redistribution of fetal cardiac output in fetal stress

The pathophysiologic continuum of poor uterine and placental blood flow associated with fetal growth restriction has to be considered the major cause of poor birth outcomes. The main attention in this context is drawn to the possibilities of an early diagnosis of imminent fetal compromise prior to and under delivery. With regard to this, the detection of a reduced fetal oxygen saturation (fetal stress) plays a crucial role, whereas an acute incident causing fetal hypoxemia has to be differentiated from a chronic hypoxemic condition. An acute hypoxemia under delivery is best detected by cardiotocography. Due to its infrequent and unpredictable occurrence, an acute antenatal hypoxemia usually escapes common surveillance methods. Fetal biometry and pulsed Doppler sonography are to be considered the most suitable methods to diagnose chronic hypoxemic fetal conditions. The interrogation of a combination of peripheral and central vessels allow the sonologist to characterize the extend of a progressively deteriorating oxygen supply. However, this correlation is not yet completely understood. Therefore, clinical consequences still have to be drawn by cardiotocographic findings indicating a global cardiac decompensation.

Fetal assessment: do newer technologies offer better assessment and outcomes?

PURPOSE OF THE REVIEW

The present manuscript reviews recent data on fetal intrapartum surveillance with special attention to new technologies.

RECENT FINDINGS

Continuous fetal heart-rate monitoring, fetal blood sampling, intrapartum stimulation tests, fetal pulse oximetry and fetal electrocardiography will be reviewed.

SUMMARY

From the available data it appears that to date the analysis of the sinus tachycardia segment of the fetal electrocardiography used in conjunction with continuous fetal heart-rate monitoring is the method of choice.

Cerebral hemoglobin concentration and oxygen saturation measured by intensity modulated optical spectroscopy in the human fetus during labor

AIMS

To quantify hemoglobin concentration and oxygen saturation in the human fetal brain using intensity modulated optical spectroscopy during labor.

METHODS

A specially designed probe was applied to the fetal scalp in 20 women during uncomplicated labor at term. Optical fibres transmitted near infra-red light to and from an intensity modulated optical spectrometer (IMOS), which detected changes in the optical parameters of the infra-red light source. Using novel off-line analytic techniques, these changes were converted into absolute measurements of oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb). Summing Hb and HbO2 gives total hemoglobin concentration (HbT) and HbO2/HbT x 100% provided measurements of cerebral saturation (SmcO2).

RESULTS

Of 20 fetuses studied, data from 10 fetuses were suitable for analysis. Over three consecutive uterine contractions, the mean (+/- SD) absolute cerebral concentrations of Hb and HbO2 were 30 +/- 18 and 46 +/- 21 mumol/l, respectively. This gave a mean cerebral HbT of 77 +/- 29 mumol/l and a mean SmcO2 of 59 +/- 12%. In the other ten fetuses insufficient light was detected to allow chromophore quantification.

CONCLUSION

These are the first absolute measurements of cerebral Hb and HbO2 in human fetuses during labor. The values of total hemoglobin are similar to those obtained in neonates with hypoxia-ischemia and the measurements of fetal cerebral oxygen saturation are similar to previously published values.

Admission cardiotocography: a randomised controlled trial

BACKGROUND

Admission cardiotocography is widely used to identify pregnancies that might benefit from continuous electronic fetal monitoring in labour. We aimed to compare the effect on neonatal outcome of admission cardiotocography versus intermittent auscultation of the fetal heart rate.

METHODS

8580 women admitted to the delivery ward of a Dublin teaching hospital who were at low risk of fetal distress in labour were randomly assigned admission cardiotocography (20 min) or the unit's usual care (intermittent auscultation only, with continuous cardiotocography only if clinically indicated). The primary outcome was moderate to severe neonatal morbidity, or perinatal mortality in the absence of a major congenital malformation. Analyses were by intention to treat.

FINDINGS

44 (1.0%) women assigned admission cardiotocography did not undergo the procedure; 15 (0.4%) assigned usual care had admission cardiotocography. The primary endpoint occurred in 56 (1.3%) of 4298 women assigned admission cardiotocography and 55 (1.3%) of 4282 in the usual-care group (relative risk 1.01; 95% CI 0.70-1.47). Other indices of neonatal morbidity also showed no differences. Despite an increase in use of continuous cardiotocography (1.39; 1.33-1.45) and fetal blood sampling (1.30; 1.14-1.47) with admission cardiotocography, there were no significant differences in the rates of caesarean delivery (1.13; 0.92-1.40), instrumental delivery (1.03; 0.92-1.16), or episiotomy (1.06; 0.99-1.13).

INTERPRETATION

Routine use of cardiotocography for 20 min on admission to the delivery ward does not improve neonatal outcome. No significant increase in operative delivery was apparent, probably because of liberal use of fetal blood sampling.

The relative risk of 'fetal distress' in pregnancy associated with meconium-stained liquor at different gestation

Pregnancies complicated with meconium-stained liquor are regarded as at risk of fetal distress. Evidence from animal and human studies indicate that passage of meconium may be related to fetal maturity. This retrospective study attempts to quantify the relative risk of non-reassuring cardiotocography or 'fetal distress' in pregnant women complicated by meconium-stained liquor for preterm, term and post-term pregnancies. A total of 9542 singleton pregnancies, delivered in a tertiary obstetric unit in Hong Kong between 1 July 1996 and 31 June 1999, were included in the study. Of these pregnancies, 1946 (20.4%) were identified as having meconium-stained liquor, ranging from thin to thick staining. There was a strong association between incidence of meconium-stained liquor (P < 0.0005) and moderate/thick meconium-stained liquor with advanced gestational age. The incidence of non-reassuring cardiotocography in women presenting with meconium-stained liquor was significantly higher (9.8% vs. 6.4%). The relative risk of non-reassuring cardiotocography in women with meconium-stained liquor increased with more advanced gestation. Close fetal surveillance during labour is required among these pregnancies. Premature labour is associated with higher incidence of fetal distress but the presence of meconium did not pose an additional risk.

Influence of maternal, obstetric and fetal risk factors on the prevalence of birth asphyxia at term in a Swedish urban population

BACKGROUND

The influence of maternal, obstetric and fetal risk factors on the prevalence of birth asphyxia at term in a Swedish urban population.

OBJECTIVE

To investigate risk factors for Apgar score-defined birth asphyxia, birth asphyxia with hypoxic-ischemic encephalopathy and birth asphyxia-related death/disability.

MATERIAL AND METHODS

Retrospective case-control study in term neonates with birth asphyxia defined as Apgar score < 7 at 5 min. Cases originating from nonasphyctic causes (e.g. infection, maternal sedation) were excluded. Hypoxic-ischemic encephalopathy was diagnosed according to criteria by Sarnat. Maternal, obstetric and fetal risk factors were registered in 225 cases of birth asphyxia diagnosed in 42 203 live births occurring in the urban Swedish population studied. A matched control group was used for statistical evaluation.

RESULTS

Asphyxia was associated with single civil status, OR = 7.1 (95%CI 2.0, 27.6); intrauterine meconium release, OR = 4.1 (95%CI 1.8, 9.8); operative delivery, OR = 8.7 (95%CI 3.4, 24.6); breech delivery, OR = 20.3 (95%CI 3.0, 416.5); oxytocin augmentation, OR = 2.9 (95%CI 1.4, 6.3); cord complication, OR = 15.8 (95%CI 2.1, 341.5); external compression to assist delivery OR = 6.2 (95%CI 1.3, 45.7); and cardiotocography score, OR = 0.5 (95%CI 0.4, 0.6). Normal fetal heart rate variability, OR = 0.4 (95%CI 0.2, 0.6), repeated late decelerations irrespective of amplitude or repeated variable decelerations, OR = 29.4 (95%CI 5.7, 540.8) or occasional late or variable decelerations, OR = 2.2 (95%CI 1.3, 3.8), and no accelerations, OR = 5.2 (95%CI 2.0, 16.4), were associated with asphyxia. Operative or instrumental delivery was more common in all three asphyxia groups compared with controls. Leanness was a risk factor for asphyxia and for hypoxic-ischemic encephalopathy. Maternal age, smoking and illnesses, time of delivery (day/night, seasonal) and previous caesarean section were not associated with birth asphyxia.

CONCLUSIONS

An association between neonatal asphyxia and cardiotocography parameters, intrauterine meconium release, operative delivery, breech delivery, single civil status, oxytocin augmentation, cord complication, external compression to assist delivery and neonatal leanness was found. Abnormal fetal heart rate variability, repeated late decelerations irrespective of amplitude or repeated variable decelerations, occasional late or variable decelerations and no accelerations were associated with asphyxia.

Meconium and fetal hypoxia: some experimental observations and clinical relevance

In an experimental study, chemically sympathectomised near term fetal sheep and a control group were subjected to repeated episodes of acute hypoxia. Despite severe hypotension and metabolic acidosis, no animal in the control group had meconium-stained amniotic fluid, whereas every animal in the sympathectomised group had heavily meconium-stained amniotic fluid at the end of the experiments. These data and the available literature do not support a direct association between acute hypoxia and meconium-stained amniotic fluid but suggest that a reduction in sympathetic neural tone must be a component of meconium passage. Clinical and experimental data on the occurrence of meconium-stained amniotic fluid are reviewed.

Late-onset fetal cardiac decelerations associated with fetal breathing movements

BACKGROUND

While late decelerations are regarded as signs of fetal hypoxemia, fetal breathing movements (FBM) associated with late decelerations invariably have normal outcomes. Could late decelerations sometimes represent FBM?

MATERIALS AND METHODS

Six patients between 37 and 42 weeks' gestation with 'late decelerations' associated with FBM (by ultrasound or tocodynamometer) during ante- or intrapartum monitoring were evaluated. Three were at high risk (diabetes, postdates, intrauterine growth restriction) and three were at low-risk.

RESULTS

'Late decelerations' arose in previously reassuring tracings. Oxygen or positional change had no effect. The decelerations were variable in length and shallow, and contained increased variability. Normal baseline rate and variability were maintained after the deceleration. Neonatal outcomes were normal.

CONCLUSION

'Late decelerations' as described are associated with normal outcome and may represent FBM. This understanding may reduce unnecessary interventions.

Differences in management and results in term-delivery in nine European referral hospitals: descriptive study

OBJECTIVE

To compose obstetric interventions around Europe.

STUDY DESIGN

A survey of obstetric practices, logistics and statistical outcomes in nine tertiary referral hospitals in Europe between November 1999 and October 2000.

RESULTS

There was wide variation in the management of pre labour rupture of the membranes at term, methods of analgesia, induction of labour, and mode of cephalic and breech delivery. Midwives practised normal deliveries at only three sites. Rates of epidural analgesia varied from 0% in Perugia to 98% in Barcelona, instrumental delivery from 3% in Perugia to 40% in Barcelona, episiotomy from 9.7% in Uppsala to 58% in Perugia, caesarean section before and during labour from 12% in Paris to 32% in Athens, vaginal breech delivery from 15% in Barcelona to 70% in Paris. The percentage of primipara varied from 40% in Uppsala to 65% in Perugia; birth weight under 2500g from 5% in Uppsala to 23% in Amsterdam, over 4000g from 3.1% in Athens to 22% in Uppsala and gestational age less than 37 weeks from 6% in Dublin to 26% in Amsterdam.

CONCLUSION

There are considerable differences in obstetric practices without any major difference in maternal and perinatal mortality.

Monitoring the fetus in labor: evidence to support the methods

Electronic fetal monitoring (EFM) was implemented across the United States in the 1970s. By 1998, it was used in 84% of all U.S. births, regardless of whether the primary caregiver was a physician or a midwife. Numerous randomized trials have agreed that continuous EFM in labor increases the operative delivery rate, without clear benefit to the baby. Intermittent auscultation (IA) is safe and effective in low-risk pregnancies and may play a role in helping birth remain normal. Clinicians and educators are encouraged to reconsider the use of IA in the care of healthy childbearing women.