The Dublin randomized controlled trial of intrapartum fetal heart rate monitoring

Women's involvement with the decision preceding their caesarean section and their degree of satisfaction

OBJECTIVE

To assess the extent to which women contribute to the decision for caesarean section and their satisfaction with the decision and procedure.

DESIGN

Observational study of women undergoing caesarean section who were interviewed using a standard proforma.

SETTING

University College Hospital, London.

PARTICIPANTS

One hundred and two consecutive women undergoing caesarean section.

RESULTS

The women's perceived reason for the caesarean section agreed with the doctors' reason in 91 cases (89.2%). Only 2/29 women having elective sections stated they had no contribution, compared with 22/73 women having emergency sections (P = 0.018, two-tailed Fisher's exact test). Twenty out of 29 women (69%) having elective procedures and 37/73 women (51%) having emergency sections recorded medium or more contribution. All women except one were 50% or more satisfied with the decision. Women's satisfaction with the operation was high in the immediate post-operative period and remained so over the following six weeks. Forty-three women (49%) said they would prefer an elective section in the next pregnancy given the choice.

CONCLUSIONS

Women undergoing caesarean section were well informed and took a considerable part in the decision-making process. This suggests that women's wishes may be playing a role in increasing caesarean section rates. High levels of satisfaction with both the decision and the procedure itself indicate that caesarean section is an acceptable method of delivery, particularly when an elective procedure.

Changes in the PR interval--fetal heart rate relationship of the electrocardiogram during fetal compromise in chronically instrumented sheep

OBJECTIVES

The evaluation of the changes in the relationship of the PR interval and fetal heart rate during prolonged fetal compromise in sheep at levels of acidosis comparable to those seen during human fetal compromise and to see whether these changes are potentially of use in the detection of fetal distress.

STUDY DESIGN

A retrospective analysis of continuous fetal electrocardiogram recordings during graded fetal hypoxemia in 20 chronically cannulated fetal sheep was performed. Baseline recordings during normoxemia were compared with recordings during hypoxemia by use of Fisher's exact test and the Student t test.

RESULTS

Sixteen of the 20 cases could be used for final analysis. Twelve showed a statistically significant change from a predominantly negative relationship between the PR interval and the fetal heart rate during normoxemia to a predominantly positive relationship during hypoxemia. Two cases showed an obvious trend in the same direction, which was statistically not significant. In two other cases no change in the relationship was observed.

CONCLUSION

A changing relation between the PR interval and the fetal heart rate is of potential use in the detection of fetal compromise.

The potential impact of PR interval analysis of the fetal electrocardiogram (FECG) on intrapartum fetal monitoring

A retrospective study was performed at the Queens Medical Centre, Nottingham, UK to evaluate the potential value of PR interval analysis of the FECG compared to conventional intrapartum assessment with fetal heart rate monitoring. Two-hundred sixty-five labours were selected for monitoring. Outcome was assessed by the number of fetal scalp blood samples (FBS) performed and the associated incidence of acidosis in the first stage of labour, the mode of delivery and whether or not this was expedited for fetal heart abnormality or an abnormal scalp pH. The condition of the fetus at delivery was assessed by arterial and venous blood acid-base status, Apgar score and the need for admission to the neonatal intensive care unit. Conventional electronic fetal heart rate monitoring (EFM) was used in all labours. The addition of PR interval assessment would potentially reduce the numbers of normal FBSs being carried out from 85.5% to 26.8% and the proportion of cases of missed acidosis at delivery from 8.5% to 4.5%. These results highlight the potential benefit of PR interval analysis in improving interpretation of the intrapartum cardiotocograph and need to be tested by prospective randomised controlled study.

Fetal oximetry monitoring: a new wonder or another mirage?

This review provides recent data and clinical opinions on a new technology in assessing fetal well-being during labor, the fetal pulse oximeter. Fetal pulse oximetry is potentially superior to electronic fetal heart rate monitoring because it allows direct assessment of both fetal oxygen status and fetal tissue perfusion. Several studies during recent years have demonstrated that fetal pulse oximetry during labor is feasible and accurate. On the other hand, these very same studies have demonstrated a few potential disadvantages and limitations of fetal oximetry. The main limitation seems to be a wide range of normal values. The correlation of fetal oximetry during labor with perinatal outcome and long-term newborn outcome has not yet been determined. In summary, fetal pulse oximetry during labor merits further randomized prospective studies, especially with regard to improvement of perinatal outcome.

Near infrared spectroscopy applied to intrapartum fetal monitoring

NIRS as a technique for intrapartum fetal monitoring is at present only able to be used as an investigative research tool. We feel that it has enormous potential to give access to previously inaccessible information about fetal cerebral haemodynamic and oxygenation changes in labour. The major limitations at present are technological, and the problems addressed in this review need to be resolved before clinicians can advance the technique. In the future, standardized measurement parameters that truly reflect cerebral oxygenation, along with a range of normality need to be established. This would require the study of very large numbers of uncomplicated labours. Comparison with data from labours complicated by what we currently call 'fetal distress' and correlation with outcome measures in the neonate would then be needed to determine abnormal patterns of change related to intracerebral hypoxia-ischaemia. This is severely limited by the current inability to measure absolute levels of oxygenation necessary to validate the method. To use the technique for routine surveillance in labour would require considerable refinement of both the equipment and the data analysis systems to improve the acceptability of the technique. It is not possible to envisage a role for NIRS in routine surveillance of low-risk pregnancies, but it may in future prove to have a role in the management of high-risk pregnancies and may well improve our understanding of intracerebral pathology.

Monitoring technology and the clinical perspective

Currently available technology requires a new look to reduce intervention as well as to improve the detection of the truly at-risk fetus. Iatrogenic causes of so-called fetal distress, in particular the administration of uterotonics without due attention to avoiding hyperstimulation, predominate as a reason for intervention. There needs to be a better definition of the starting point, i.e assessment of the fetal condition and identification of any risk factors, such as oligohydramnios and growth retardation, that might diminish fetal reserve. This will allow 'customization' of surveillance and management according to the needs of each individual fetus. There also needs to be better training and better agreement about the end-point of monitoring. For prospective surveillance, the aim is to avoid rather than to identify damage, and the definition of the appropriate point for intervention needs to come from better consensus on what is and what is not acceptable management based on current knowledge. New technology holds the promise that it can give trended information during labour, allow early recognition of problems and reduce unnecessary intervention. However, there is a need to ensure reliability and reproducibility of the readings before a new method is released. Co-operation with industry is essential, but the roles need to be well defined and the ultimate responsibility for establishing the role of a new technique has to come from the clinicians involved in intrapartum care.

The fetal electrocardiogram

Advances in microprocessing technology have made fetal ECG analysis a feasible adjunct to fetal surveillance. Time interval and morphology changes of the FECG occur during fetal hypoxia. The use of these changes to detect a fetus at risk of intrapartum asphyxia awaits validation in terms of both future and ongoing clinical trials. Recognition of FECG changes during decelerations may improve the sensitivity of EFM. Antepartum FECG analysis has potential for the detection of a number of pathological fetal conditions, including intrauterine growth retardation, but remains hampered by low signal-to-noise ratios, rendering successful signal acquisition unreliable.

Metaanalysis for the obstetrician-gynecologist

To provide guidance to obstetricians and gynecologists for using findings from metaanalyses in clinical practice, we describe the principles and methods of metaanalysis, including its strengths and weaknesses. Then we illustrate these principles by reviewing four metaanalyses published recently in the American Journal of Obstetrics and Gynecology by using a systematic approach to evaluation based on 15 questions. In these published metaanalyses most of the questions are addressed, but we noted an absence of attention to coding aspects in all studies. The usefulness of metaanalysis largely depends on the quality of the studies that are synthesized, the conduct of the metaanalysis, and the reporting of the methods and results. Proper use of metaanalyses requires an understanding of the strengths and weaknesses of the method and attention to the manner of reporting. The principles of metaanalysis are not complex, and the potential benefits can be enormous for patient care.

On intrapartum fetal monitoring

The currently advised conduct for intrapartum surveillance of the fetus is either intermittent auscultation of continuous electronic monitoring, depending on the physician's preference. This applies to all, normal or high-risk, conditions. The bases for this recommendation, a number of controlled studies comparing the two methods, showed no better neonatal outcomes and increased cesarean section rates with electronic fetal monitoring. A review of the works pertaining to fetal development of cardiovascular and central nervous systems and their response to various pathophysiologic conditions (in animals and humans) was carried out in an effort to find an explanation for this apparently uncongruous position. It was found that fetal responses to seemingly comparable conditions are radically different depending on age of gestation. Many authors have pointed this out for the human fetus. However, for interpretation of electronic fetal monitoring in labor, various standard, nondescriptive, confusing words are used to imply the need for rapid intervention. The complete lack of uniform interpretation has been shown in studies comparing interobserver and intraobserver variations. This may be the consequence of poor or superficial teaching of a tool that requires much study and hard work for useful application. The inescapable conclusion is unpleasant but inevitable: to use electronic fetal monitoring properly it is necessary to start a new learning of the physiology of the fetus, its changing evolution as pregnancy advances, its different responses under stress or distress, and the various ways these are represented in electronic fetal monitoring tracings. These efforts take dedication and time spent in labor suites collating tracings with neonatal condition. Only by doing this will it be possible to assist the laboring patients with a useful tool that, so far, has not been adequately applied because of insufficient understanding.

Uncertain value of electronic fetal monitoring in predicting cerebral palsy

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Evaluation of a fetal monitoring education program

OBJECTIVE

To evaluate the effectiveness of a fetal monitoring education program in increasing nurses' knowledge and clinical skills.

DESIGN

Multicenter randomized control trial.

SETTING

Twelve hospitals in eastern Ontario, Canada.

PARTICIPANTS

One hundred nine volunteer registered nurses randomly assigned, within each hospital, to an experimental (n = 47) or control (n = 62) group. Ninety-six nurses (40 in the experimental group and 56 in the control group) completed the 6-month follow-up (88% retention).

INTERVENTIONS

The experimental group participated in a 1-day fetal monitoring workshop and a review session 6 months later.

MAIN OUTCOME MEASURES

Performance on a 45-item knowledge test and a 25-item skills checklist. The passing score was at least 75% correct on each test.

RESULTS

The percentage of nurses in the experimental group passing both the knowledge and the clinical skills tests after the workshop was significantly higher (p < 0.01) than that of the nurses in the control group: 68.1% versus 6.5%, respectively. A large difference between the groups remained at the 6-month follow-up (experimental, 45%; control, 6.5%). The performance of the nurses in the experimental group improved to an 85% pass rate after they attended the 6-month review session.

CONCLUSION

This comprehensive, research-based program is effective in increasing fetal monitoring knowledge and clinical skills.

Why has conventional intrapartum cardiotocography not given the expected results?

It is probable that conventional electronic fetal monitoring (EFM) has reduced the intrapartum death rate, but the expected dramatic reduction in neurological handicap has not occurred. There are two reasons for this: the majority of infants, who develop neurological problems have been harmed before the onset of labor, and the method of EFM has been more difficult to use in daily routine than expected. However, EFM is the best method we have to monitor high risk cases and the results can be improved by better training of the staff.

Case-control study of antenatal and intrapartum risk factors for cerebral palsy in very preterm singleton babies

The increase in survival of very preterm babies during the 1980s was accompanied by a sharp increase in the rate of cerebral palsy in this group. The relation between antenatal and intrapartum factors and cerebral palsy in such babies has not been well defined. To identify adverse and protective antenatal and intrapartum factors we undertook a case-control study of 59 very preterm babies who developed cerebral palsy, identified from a population-based register, and 234 randomly selected controls. The frequency of cerebral palsy decreased with increasing gestational age and birthweight. Antenatal complications occurred in 215 (73%) of the women with preterm deliveries. Factors associated with an increased risk of cerebral palsy after adjustment for gestational age were chorioamnionitis (odds ratio 4.2 [95% CI 1.4-12.0]) prolonged rupture of membranes (2.3 [1.2-4.2]), and maternal infection (2.3 [1.2-4..5]). Pre-eclampsia was associated with a reduced risk of cerebral palsy (0.4 [0.2-0.9]), as was delivery without labour (0.3 [0.2-0.7]). There was no increased risk of cerebral palsy with intrauterine growth retardation (1.0 [0.9-1.1]). The effect of rigorous management of adverse antenatal factors on the frequency of cerebral palsy in very preterm babies should be tested in randomised controlled trials.

The mortality and morbidity associated with umbilical cord prolapse

OBJECTIVE

To examine the management of cord prolapse and its morbidity and mortality.

DESIGN

Retrospective study of consecutive babies born after cord prolapse, identified using the Oxford Obstetric Data System, and those with registered handicap, identified by the Oxford Region Register of Early Childhood Impairments.

SETTING

District maternity hospital managing more than 6000 deliveries annually.

SUBJECTS

One hundred and thirty-two babies born after the identification of cord prolapse in the John Radcliffe Hospital between January 1984 and December 1992.

MAIN OUTCOME MEASURES

Survival rates, condition at birth assessed by Apgar scores at 1 and 5 minutes and blood gas values on cord blood samples, and incidence of major handicap at three years of age.

RESULTS

The incidence of cord prolapse was 1 in 426 total births. There were six stillbirths and six neonatal deaths. One baby died as a result of birth asphyxia. The uncorrected perinatal mortality rate was 91 per 1000. Of 120 survivors, only one baby was known to suffer a major neurological handicap. Electronic cardiotocographs aided the diagnosis of cord prolapse in 41% of cases. Apgar scores were better with a shorter diagnosis to delivery interval, but cord gas results did not correlate well with Apgar scores or the diagnosis to delivery interval.

CONCLUSIONS

Cord prolapse occurs with a relatively stable incidence in this population irrespective of changes in obstetric practices. Despite the high incidence of ominous cardiotocographs, low Apgar scores and acidaemia on blood gas analysis, the fetal outcome is not as poor as might be expected and mortality is predominantly attributable to congenital anomalies and prematurity rather than birth asphyxia.

Asphyxia

The prevention of fetal asphyxia or hypoxia starts with prepregnancy counseling and continues with careful antenatal care and intrapartum fetal surveillance. Further progress in eliminating antepartum and intrapartum deaths will only be made when it is accepted that, even with intense investigation by detailed autopsy, the cause of many deaths remains unknown. Many of these deaths may be ascribed to hypoxia. In the future, with more detailed non-invasive probing with CAT scanning and magnetic resonance imaging, other causes may be determined. The mother at risk of hypoxia requires specialized attention. Such mothers will include those with severe cardiac, pulmonary or circulatory problems. Others will be those with endocrine problems, such as diabetes or thyroid dysfunction. At present, failure of fetal growth is generally ascribed to hypoxia, but undoubtedly, in solution to such problems of possible hypoxia is elective delivery at the appropriate time. What Hensleig said in 1986 (Hensleig et al, 1986) is equally true today: 'Preventative programmes will remain unsuccessful until the causation of cerebral palsy is more understood. What we are presently lacking is an understanding of the underlying conditions responsible for brain injury when asphyxia occurs despite our best efforts. While we have learned much about the causation and prevention of perinatal mortality very little has been established about the causation and prevention of cerebral palsy'. Finally, Hall (1989), in a review of birth asphyxia and cerebral palsy, concludes the following five points. 1. The incidence of cerebral palsy is not falling despite improved obstetrics. 2. The cause of more than 90% of cases of cerebral palsy remains unknown. 3. Asphyxia is hard to define and measure and is rarely the cause of cerebral palsy. 4. Hypoxic ischaemic encephalopathy is the most reliable indicator of asphyxia. 5. Neither traditional clinical signs nor electronic monitoring allow reliable recognition of asphyxia.

How useful is intrapartum electronic fetal heart rate monitoring?

It is essential for an obstetric anesthesiologist to be aware of the fetal status before undertaking care of the laboring mother. In the last 20 years electronic fetal monitoring has been the most widely used technique of evaluating the fetus in labor. Recently however, the ability to predict or improve fetal outcome using traditional interpretation has been questioned. This review presents a summary of the current technology and interpretation of intrapartum electronic fetal monitoring, as well as a discussion of its limitations and some of the developments in this field which may help improve the accuracy of fetal assessment. The new developments in fetal monitoring discussed in this article are computerized assessment of fetal heart tracings, heart rate variability analysis, fetal electrocardiogram waveform analysis, abdominal detection of fetal ECG, fetal scalp oxygen saturation, fetal pH sampling and transcutaneous oxygen and carbon dioxide measurement.

The prediction of fetal acidosis at birth by computerised analysis of intrapartum cardiotocography

OBJECTIVE

To assess the capability of a computer software interpretation program, using intrapartum fetal heart rate and intrauterine pressure as recorded in a cardiotocogram to predict fetal acidosis at birth.

DESIGN AND SUBJECTS

A retrospective analysis of digitised fetal heart rate and uterine activity values obtained from 73 high risk women in labour.

SETTING

Two university teaching hospitals.

METHODS

A computer software program was constructed to analyse the digitised data and predict acidosis. The results of the analysis were compared with actual umbilical arterial blood pH and base excess at delivery.

RESULTS

The software cardiotocogram interpreter was able to predict a pH of less than 7.15 with an accuracy of 77%, a sensitivity of 88% and specificity of 75% in this set of data. It was able to predict a base excess of less than -8 mmol/l with an accuracy of 81%, a sensitivity of 76% and specificity of 82%.

CONCLUSIONS

A computerised method of analysing fetal heart rate and uterine activity using a simple algorithm has demonstrated a capability to predict fetal acidosis at the time of delivery. Further research in this area is warranted.

Perinatal asphyxia: assessing its causal role and timing

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

Fetal monitoring--midwifery attitudes

OBJECTIVE

to survey midwives' attitudes and practices related to intrapartum fetal monitoring.

DESIGN

descriptive correlational study.

SETTING

regional and district maternity unit and related community area within one health authority.

PARTICIPANTS

all midwives were invited to participate. Two hundred and forty two questionnaires were administered and 117 were returned (48% response rate).

MEASUREMENTS AND FINDINGS

in the questionnaire information was collected on professional/demographic details, education and practices related to intrapartum fetal monitoring, together with a 20-item attitude scale which encompassed attitudes towards fetal monitoring and related issues. As expected, the findings suggest that midwives' preferred methods of fetal monitoring varied with the client's risk category. However, midwife preference did not necessarily match actual choice of method. There are many factors influencing choice, not least of which is confidence in ability. Significant differences were found between midwives.

KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

the findings highlight some of the issues relating to individual confidence. 97% of the midwives felt they would benefit from in-service training in CTG interpretation. The findings support the development of continuing in service education programmes for midwives.

Nulliparous caesarean section in the home of active management of labour

The world-wide incidence of Caesarean section continues to rise with dystocia recognized as the major indication. Active management of labour has been proposed as an alternative treatment to Caesarean section for dystocia. At the National Maternity Hospital, Dublin, a recent increase in the Caesarean section rate has been observed. This retrospective review reveals this to be due to other indications.

Midwife managed delivery unit: a randomised controlled comparison with consultant led care

OBJECTIVE

To examine whether intrapartum care and delivery of low risk women in a midwife managed delivery unit differs from that in a consultant led labour ward.

DESIGN

Pragmatic randomised controlled trial. Subjects were randomised in a 2:1 ratio between the midwives unit and the labour ward.

SETTING

Aberdeen Maternity Hospital, Grampian.

SUBJECTS

2844 low risk women, as defined by existing booking criteria for general practitioner units in Grampian. 1900 women were randomised to the midwives unit and 944 to the labour ward.

MAIN OUTCOME MEASURES

Maternal and perinatal morbidity.

RESULTS

Of the women randomised to the midwives unit, 647 (34%) were transferred to the labour ward antepartum, 303 (16%) were transferred intrapartum, and 80 (4%) were lost to follow up. 870 women (46%) were delivered in the midwives unit. Primigravid women (255/596, 43%) were significantly more likely to be transferred intrapartum than multi-gravid women (48/577, 8%). Significant differences between the midwives unit and labour ward were found in monitoring, fetal distress, analgesia, mobility, and use of episiotomy. There were no significant differences in mode of delivery or fetal outcome.

CONCLUSIONS

Midwife managed intrapartum care for low risk women results in more mobility and less intervention with no increase in neonatal morbidity. However, the high rate of transfer shows that antenatal criteria are unable to determine who will remain at low risk throughout pregnancy and labour.

Development, evaluation and validation of an intelligent system for the management of labour

Over the past 4 years our group has developed a prototype intelligent system which applies captured expert knowledge to support clinical decision-making during labour. This chapter presents a review of the system and the progress made to date. The system classifies the same features from the CTG as experienced clinicians using numerical algorithms and a small neural network. This hybrid approach has been shown to obtain a comparable performance with experts. The CTG information, together with the patient information and labour events, are collectively passed to an expert system for processing. The expert system interprets this combined data using a database of over 400 rules which are used to recommend action. Importantly, as the knowledge is rule-based, it allows the system to explain the reasoning which led it to recommend a certain action. In this way, the clinician is not expected to blindly follow the system's recommendations but can reach an informed judgement in the same way they might by discussing the case with an experienced informed colleague. After two internal evaluations had found the system obtained a performance comparable with local experts, an extensive external validation was undertaken. This study involved 17 experts from 16 leading centres within the UK. Each expert and the system reviewed 50 cases twice, at least one month apart which contained those CTGs considered most difficult to interpret selected from a database of 2400 high-risk labours. This study found that the majority of experts agreed well and were consistent in their management of the cases. The system obtained a performance that was indistinguishable from the experts, except it was more consistent, even when used by an engineer with little knowledge of labour management. This study demonstrates the potential for intelligent systems to transform the cardiotocograph from a difficult-to-use, ineffective recorder of fetal heart rate, to an interactive and effective decision support tool capable of raising the skills of staff.

Intermittent versus continuous electronic monitoring in labour: a randomised study

OBJECTIVE

To compare the efficacy in detecting signs of fetal hypoxia in labour of intermittent (I-group) versus continuous (C-group) electronic fetal monitoring in women with low or moderate risk factors for fetal distress.

DESIGN

A prospective, randomised study.

SETTING

A tertiary referral centre.

SUBJECTS

Four thousand and forty-four parturients at low risk for obstetric complications with a reactive fetal heart rate admission test at arrival in labour. During the study period (October 5 1989 to May 31 1991), 5647 women were delivered in the labour ward. Of these, 1178 women (20.9%) were excluded because of high risk factors in pregnancy or at admission for labour, including women undergoing elective caesarean section. Of the remaining 4469 women 4044 (90.5%) were randomised to either intermittent (n = 2015) or continuous monitoring (n = 2029) during the first stage of labour.

METHODS

In the C-group the fetal heart rate was recorded continuously with electronic fetal monitoring during the first stage of labour. In the I-group the fetal heart rate was recorded with electronic fetal monitoring for 10 to 30 min every 2 to 2.5 h during the first stage of labour, and the fetal heart rate was auscultated every 15 to 30 min in between recording periods. If complications occurred, recording was changed to continuous. In the second stage of labour all the women were monitored continuously. Umbilical cord artery acid-base status was assessed at birth.

MAIN OUTCOME MEASURES

Duration of electronic fetal monitoring, rates of abnormal fetal heart rate patterns, caesarean section for fetal distress, acidosis in umbilical cord arterial blood at birth, Apgar scores of less than 7 at 1 or 5 min, and referrals to the neonatal intensive care unit.

RESULTS

There were no significant differences between the study groups in the incidence of ominous fetal heart rate recordings: 6.3% (I-group) versus 6.6% (C-group), or the interval from arrival to first detected abnormal fetal heart rate, although the number of suspicious fetal heart rate patterns was higher in the C-group (28.6%) than in the I-group (24.6%). In the I-group electronic fetal monitoring was performed for (median monitoring time) 38.8% of the first stage of labour as compared with 78.6% in the C-group. The incidence of caesarean section for fetal distress was similarly low in both groups: 1.2% versus 1.0%. There were no significant differences in the immediate neonatal outcome in terms of umbilical artery pH, Apgar scores, or admissions to the neonatal care unit.

CONCLUSIONS

Intermittent use of electronic fetal monitoring at regular intervals (with stethoscopic auscultation in between) appears to be as safe as continuous electronic fetal monitoring in low risk labours.

Cerebral palsy and neonatal encephalopathy

A retrospective cohort study was carried out to test the hypothesis that children born at term with cerebral palsy with signs of neurological dysfunction preceded by depression at birth (termed neonatal encephalopathy) differ from those without such signs in the frequency of antenatal and perinatal factors, and in the severity and characteristics of their impairment and disability. The study was carried out in the area covered by Oxford Regional Health Authority. Antenatal, intrapartum, neonatal factors, and the later clinical status of the two groups of children were used as the main outcome measures. Although most maternal and antenatal characteristics were similar in the two groups, the mothers of children with a history of neonatal encephalopathy were more likely to be primigravidae (odds ratio (OR) 2.0; 95% confidence interval (CI) 1.0 to 4.3) and to have a pregnancy of greater than 41 weeks' gestation (OR 3.5; 95% CI 1.0 to 12.1). Intrapartum complications were more frequent in the neonatal encephalopathy group: meconium staining of the amniotic fluid (OR 3.5; 95% CI 1.5 to 7.8), an ominous first stage cardiotocograph (OR 10.2; 95% CI 2.9 to 36.4), with a longer median duration of abnormality (200 v 48 minutes). At 5 years of age those with neonatal encephalopathy were more likely to have developed spastic quadriplegia (OR 4.8; 95% CI 2.2 to 10.5), to have visual impairment (OR 3.0; 95% CI 1.0 to 8.6), and to be non-walking (OR 4.0; 95% CI 1.8 to 8.8) than those without neonatal encephalopathy. Children with cerebral palsy who were born at term and have neonatal encephalopathy are more likely to have had signs of intrapartum asphyxia and are more likely to have a more severe form of cerebral palsy than those without a history of neonatal encephalopathy. Although this group represents only one in 10 of all cases of cerebral palsy, some of these may be obstetrically preventable.

Case-control study of intrapartum care, cerebral palsy, and perinatal death

OBJECTIVE

To investigate the relation between suboptimal intrapartum obstetric care and cerebral palsy or death.

DESIGN

Case-control study.

SETTING

Oxford Regional Health Authority.

SUBJECTS

141 babies who subsequently developed cerebral palsy and 62 who died intrapartum or neonatally, 1984-7. All subjects were born at term of singleton pregnancies and had no congenital anomaly. Two controls, matched for place and time of birth, were selected for each index case.

MAIN OUTCOME MEASURES

Adverse antenatal factors and suboptimal intrapartum care (by using predefined criteria).

RESULTS

Failure to respond to signs of severe fetal distress was more common in cases of cerebral palsy (odds ratio 4.5; 95% confidence interval 2.4 to 8.4) and in cases of death (26.1; 6.2 to 109.7) than among controls. This association persisted even after adjustment for increased incidence of a complicated obstetric history in cases of cerebral palsy. Neonatal encephalopathy is regarded as the best clinical indicator of birth asphyxia; only two thirds (23/33) of the children with cerebral palsy in whom there had been a suboptimal response to fetal distress, however, had evidence of neonatal encephalopathy; these 23 formed 6.8% of all children with cerebral palsy born to residents of the region in the four years studied.

CONCLUSION

There is an association between quality of intrapartum care and death. The findings also suggest an association between suboptimal care and cerebral palsy, but this seems to have a role in only a small proportion of all cases of cerebral palsy. The contribution of adverse antenatal factors in the origin of cerebral palsy needs further study.

Randomised controlled trial of intrapartum fetal heart rate monitoring

OBJECTIVE

To compare effectiveness of different methods of monitoring intrapartum fetal heart rate.

DESIGN

Prospective randomised controlled trial.

SETTING

Referral maternity hospital, Harare, Zimbabwe.

SUBJECTS

1255 women who were 37 weeks or more pregnant with singleton cephalic presentation and normal fetal heart rate before entry into study.

INTERVENTIONS

Intermittent monitoring of fetal heart rate by electronic monitoring, Doppler ultrasound, use of Pinard stethoscope by a research midwife, or routine use of Pinard stethoscope by attending midwife.

MAIN OUTCOME MEASURES

Abnormal fetal heart rate patterns, need for operative delivery for fetal distress, neonatal mortality, Apgar scores, admission to neonatal unit, neonatal seizures, and hypoxic ischaemic encephalopathy.

RESULTS

Abnormalities in fetal heart rate were detected in 54% (172/318) of the electronic monitoring group, 32% (100/312) of the ultrasonography group, 15% (47/310) of the Pinard stethoscope group, and 9% (28/315) of the routine monitoring group. Caesarean sections were performed for 28% (89%), 24% (76), 10% (32), and 15% (46) of the four groups respectively. Neonatal outcome was best in the ultrasonography group: hypoxic ischaemic encephalopathy occurred in two, one, seven, and 10 cases in the four groups respectively; neonatal seizures occurred only in the last two groups (six and nine cases respectively); and deaths occurred in eight, two, five, and nine cases respectively.

CONCLUSIONS

Abnormalities in fetal heart rate were more reliably detected by Doppler ultrasonography than with Pinard stethoscope, and its use resulted in good perinatal outcome. The use of relatively cheap ultrasound monitors should be further evaluated and promoted in obstetric units caring for high risk pregnancies in developing countries with scarce resources.

The use of the fetal electrocardiogram in labour

It is clear that considerably more work needs to be done before fetal ECG waveform analysis can be adopted for the purposes of routine fetal monitoring. It must be decided exactly what we want fetal ECG waveform analysis to achieve. If it is to reduce the number of operative deliveries performed in the presence of normal or intermediate CTG patterns then the fetal ECG shows promise, but its physiological significance in this context remains uncertain. If fetal ECG analysis is to be related to outcome, as opposed to events in labour, then several very large well conducted randomised prospective controlled trials will be needed. At present a large multicentre study (European Community Concerted Action Project 1989) is taking place in which a large number of intrapartum ECG records are being collected, blinded to the clinician and stored onto optical disc via a personal computer. A multicentre study in the United Kingdom using the Nottingham system is also being planned. We need await the outcome of these to verify if any of a variety of fetal ECG variables can be related to outcome. It behoves us to validate fetal ECG analysis against outcome measures that truly indicate whether the labour process has compromised or damaged the fetus. We must not fall into the trap of yet again wholeheartedly embracing a test that has not been properly validated.

Problems in the clinical use of intrapartum fetal ECG monitoring

Commercial machines are now available to monitor the fetal electrocardiograph in labour (Cinventa, Sweden). We report our experience of the first one hundred women we monitored by this method. They were divided into five groups dictated by the change in the fetal scalp electrode used for monitoring and the changes made in the computer software used for signal processing. There were progressive significant improvements in the ability of the system to produce a continuous heart rate trace such that it became acceptable for routine fetal monitoring. The quality of the electrocardiogram improved to 50% of the 'check ECG complexes' being printed accurately. Electrical signal distortion causing baseline wander is however the significant remaining problem. On-line analysis of the T/QRS ratio improved very significantly from 36% to 84% of the monitoring time. There were no significant improvements in the recordings made in the second stage, which remained poorer in quality and reliability in all groups. As well as changes in the computer software, the use of a single helix electrode and practical experience contributed to the improvements.

Artificial versus natural surfactant--can we base clinical practice on a firm scientific footing?

Now that surfactant is in widespread use, clinical trials are beginning to address the critical question of whether the choice of surfactant really matters in terms of major morbidity and mortality. The trials reported so far focus on the effects of artificial and natural surfactant on acute gas exchange and duration of oxygen or ventilation therapy. Although the number of infants recruited to comparative trials of different surfactants is increasing, we are still a long way from being able reliably to answer the question 'Which type of surfactant should we use and under what circumstances?' In understanding the uncertainty in this field it is pertinent to consider the interrelationships between three levels of research for any new therapy in clinical science. At the first level animal studies or case reports suggest potential clinical benefits. At the second, more focused physiological studies and trials address questions of mechanism. At the third, definitive randomised trials compare major adverse clinical outcomes in human patients. Only studies conducted at this third level can finally establish clinical practice on a firm scientific footing. In this review, a preliminary meta-analysis of 801 patients recruited in three trials of artificial (Exosurf) versus natural (Survanta) surfactant shows no clear advantage for either surfactant but does not rule out moderate differences in major adverse outcomes. To establish reliably whether such differences exist will require large multicentre clinical trials.(ABSTRACT TRUNCATED AT 250 WORDS)

Caesarean section in Britain and the United States 12% or 24%: is either the right rate?

The rate of caesarean section (CSR) in Great Britain (GB) and the U.S.A., 12% in England in 1989 ascertained from a survey performed by the authors, and 24% according to official U.S. figures, is higher than warranted by the known and agreed obstetric indications for this operation, which suggest a rate of 6-8% would be adequate. It is argued that the fall in perinatal mortality which has occurred over the period during which the CS rate has risen is not the main reason for this fall. The training of obstetricians to deal with anxiety, provision of primary maternity care by appropriately trained midwives and general or family practitioners, and changes in management protocols could cut the CSR. The number of women undergoing surgery every year in the U.K. could be reduced by 20,000 and in the U.S.A. by 470,000 if the rate of 6% were achieved. In studies of midwifery care the CSR is even lower and it is possible that labour proceeds more efficiently if the woman knows her caregivers and labours at home, as in The Netherlands. Although CS is much safer than in the past it is still more likely to result in the death of the woman and has significant morbidity for the woman and economic costs for society.

Cesarean section: medical benefits and costs

Cesarean section rates have risen dramatically in the U.S. over the past 20 years. Although infant mortality has declined during the same period, there is little evidence that more frequent cesarean surgery is the cause. Cesareans save lives or benefit health in certain circumstances, but the incidence of those indications has not increased. Cesarean section also has risks, the most significant for the infant being iatrogenic prematurity or respiratory disease. Maternal mortality is 2-4 times higher and morbidity is 5-10 times higher after a cesarean compared to vaginal birth. The four indications responsible for most of the rise in cesarean rates--previous cesarean, dystocia, breech presentation, and fetal distress--are those conferring the least clear-cut benefit. Demographically, women who are most likely to experience pregnancy complications, low birth weight births, or infant mortality are least likely to have a cesarean. Social, economic, and other factors seem to have a greater influence on the decision to perform a cesarean than does expected medical benefit. The development of neonatal intensive care, expanded access to prenatal care, and greater availability of abortion and family planning have contributed more to falling infant mortality. It has been estimated that approximately half the cesareans currently performed in the U.S. are medically unnecessary, resulting in considerable avoidable maternal mortality and morbidity, and a cost of over $1 billion each year.