Analysis of intrapartum fetal deaths: their decline with increasing electronic fetal monitoring

A Review of Signal Processing Techniques for Non-Invasive Fetal Electrocardiography

Fetal electrocardiography (fECG) is a promising alternative to cardiotocography continuous fetal monitoring. Robust extraction of the fetal signal from the abdominal mixture of maternal and fetal electrocardiograms presents the greatest challenge to effective fECG monitoring. This is mainly due to the low amplitude of the fetal versus maternal electrocardiogram and to the non-stationarity of the recorded signals. In this review, we highlight key developments in advanced signal processing algorithms for non-invasive fECG extraction and the available open access resources (databases and source code). In particular, we highlight the advantages and limitations of these algorithms as well as key parameters that must be set to ensure their optimal performance. Improving or combining the current or developing new advanced signal processing methods may enable morphological analysis of the fetal electrocardiogram, which today is only possible using the invasive scalp electrocardiography method.

Trends in intrapartum fetal death, 1979-2003

OBJECTIVES

This study was undertaken to analyze trends in intrapartum fetal death and rates of perinatal autopsy over a 25-year period in Dublin, Ireland.

STUDY DESIGN

A retrospective multicenter analysis of 508,342 nonanomalous infants 500 g or more, delivering in 3 tertiary-referral university institutions between 1979-2003.

RESULTS

There has been a significant downward trend in the rate of intrapartum fetal death over the past 25 years (P < .0001). Nulliparous labors were statistically more likely to be complicated by an intrapartum fetal demise than parous labors (odds ratio, 1.49; 95% confidence interval [CI], 1.16-1.92; P = .0018). Intrapartum deaths secondary to hypoxia fell significantly over the study period (P < .0001). Infants of multiple gestations were twice as likely to die in labor as singletons (odds ratio, 2.2; 95% CI, 1.22-3.74; P = .0058). Rates of perinatal autopsy fell significantly over the 25 years studied (P < .0001).

CONCLUSION

There has been a significant fall in rates of intrapartum fetal death. This has primarily resulted from a reduction in deaths attributable to intrapartum hypoxia. Infants of multiple gestations still retain a significantly higher chance of intrapartum death. The fall in uptake rates of perinatal autopsy in recent years is concerning.

A review of intrapartum fetal deaths, 1982 to 2002

This study identifies cases of unexpected intrapartum fetal deaths over 20 years in a Canadian tertiary hospital. Of 121,659 births, 82 were intrapartum deaths. Eleven fetuses were considered viable and nonanomalous. Six deaths were deemed ideally preventable. Application of electronic fetal heart rate monitoring and rapid operative delivery may reduce the already low rate of intrapartum fetal deaths.

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.

"Evidence" and midwifery practice

Evidence-based care has become the new standard in the clinical disciplines. It represents a paradigm shift for clinicians, toward greater inclusion of research findings in patient care decisions. Randomized trials are the "gold standard" in clinical research and provide the strongest evidence for a treatment or intervention. But, randomized trials have limitations and cannot address all important clinical questions. Research using observational, descriptive, and qualitative methods also has a place in generating evidence for practice. Balancing the needs of individual women against what is learned from research with groups or populations is a challenge for midwives.

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.

A case-control study of intrapartum stillbirths

OBJECTIVE

To determine antenatal and intrapartum risk factors for intrapartum stillbirths in a total population.

DESIGN

Matched case-control study.

SETTING

Western Australia 1980-1983.

SUBJECTS

Intrapartum stillbirths of > or = 1000 g birthweight (cases) and liveborn infants (controls) individually matched for year of birth, plurality, sex and birthweight of infant and race of mother.

RESULTS

Intrapartum stillbirths were more likely than controls to have had placental abruption (OR = 9.55, CI = 2.09-43.69), fetal distress (OR = 4.64, CI = 1.92-11.19), cord prolapse (OR = 10.00, CI = 1.17-85.60) and unhealthy placentas (OR = 2.26, CI = 1.13-4.52), and more likely to have been born by vaginal breech manoeuvre (OR = 3.51, CI = 1.40-8.80) and emergency caesarean section (OR = 2.15, CI = 1.13-4.10); mothers of intrapartum stillbirths were less likely to have had no labour (OR = 0.14, CI = 0.04-0.55) and to have been delivered normally (OR = 0.20, CI = 0.10-0.40). Mothers of cases born by emergency caesarean section had longer labours than mothers of controls born by this method. All intrapartum stillbirths with breech presentation were born by vaginal breech manoeuvre compared with only 53% of the controls; the remainder of the controls were born by caesarean section.

CONCLUSIONS

Results indicate that little could have been done early in pregnancy to prevent the intrapartum stillbirths as no antenatal risk factors predicted these deaths. Most of the risk factors identified related to labour and delivery problems. Considering cases born by emergency caesarean section, delivery of the mother earlier in labour may have prevented some of the deaths.

Fetal and neonatal mortality of small-for-gestational age infants. A 15-year study of 381 cases

Fetal and neonatal mortality of small-for-gestational age (SGA) infants in 1968-1982 were studied in the region of the University Central Hospital of Turku, Finland. During the study period, there were 254 fetal and 127 neonatal deaths in SGA infants. The fetal mortality rate of SGA infants declined from 49.9/1000 to 14.0/1000. The neonatal mortality rate of SGA infants declined from 23.8/1000 to 8.3/1000. The severely SGA infants with a birth weight below the 2.5th percentile had three times higher neonatal mortality rates than SGA infants with a birth weight between the 2.5th and the 10th percentiles. The main causes of fetal deaths were maternal diseases, placental and cord complications and fetal malnutrition, even though there was a decline in all these groups. Malformations remained the main cause of neonatal death during the study period, while there was a decline in deaths due to asphyxia and respiratory distress syndrome (RDS). The high mortality rates of SGA infants emphasize the need for early diagnosis and special attention during pregnancy, delivery and the neonatal period.

Birth trauma and brain damage

Birth trauma is a rare primary cause of perinatal death, occurring at most only once in every 1000-2000 births. As a cause of brain damage and later handicap it is often difficult to dissociate injury at birth from the concomitant effects of asphyxia, growth retardation or preterm delivery. A continuum of reproductive casualty has been postulated, but for trauma is not proven. Among children with cerebral palsy and severe mental retardation trauma may be implicated in a few cases, possibly 1-2 of 1000 deliveries. Vaginal breech delivery has been related to a higher incidence of minimal brain damage syndromes and some of this damage probably has its origin in perinatal trauma. The pregnancies where there is particular risk of birth trauma include those where the infant is large for gestational age, has intrauterine growth retardation, is delivered preterm, is vaginally delivered in breech presentation or is from multiple gestation. Particular care must be given to diagnosis and preventive measures in these cases and competent handling is required if the disaster of brain damage caused by traumatic birth is to be minimized.

A prospective comparison of selective and universal electronic fetal monitoring in 34,995 pregnancies

We investigated the effects of using intrapartum electronic fetal monitoring in all pregnancies, as compared with using it only in cases in which the fetus is judged to be at high risk. Predominant risk factors included oxytocin stimulation of labor, dysfunctional labor, abnormal fetal heart rate, or meconium-stained amniotic fluid. This prospective alternate-month clinical trial took place over a 36-month period during which 34,995 women gave birth. In alternate months, either 7 (for "selective monitoring") or 19 (for "universal monitoring") fetal monitors were made available in the labor and delivery unit. During the "selective" months, 6420 of 17,409 women (37 percent) were electronically monitored, as compared with 13,956 of 17,586 women (79 percent) during the "universal months." Universal monitoring was associated with a small but significant increase in the incidence of delivery by cesarean section because of fetal distress, but perinatal outcomes as assessed by intrapartum stillbirths, low Apgar scores, a need for assisted ventilation of the newborn, admission to the intensive care nursery, or neonatal seizures were not significantly different. We conclude that not all pregnancies, and particularly not those considered at low risk of perinatal complications, need continuous electronic fetal monitoring during labor.

Advances in perinatal care and declining regional neonatal mortality in Finland, 1968-82

Neonatal mortality (NNM) was investigated in the region of the University Central Hospital of Turku (UCHT), Finland, during a 15-year period from 1968 till 1982. During the study period 81 620 liveborn infants were born. The NNM rate declined from 13.5 in 1968 to 3.0 in 1982 during the study period. Significant declines occurred in NNM due to respiratory distress syndrome (RDS) and asphyxia. The decline in NNM was more obvious during the early neonatal period (0-6 days after birth) and in the low birth weight (LBW) group (BW less than 2500 g). We believe that centralization of obstetric and neonatal services in risk cases and the new neonatal intensive care accounted for the decline in NNM.

Fetal death during labor: an epidemiologic indicator of level of obstetric care

The effect of level of perinatal care on rates of intrapartum fetal death was studied in births of infants weighing greater than 1000 gm in New York City in 1976 to 1978. With potential confounding by birth weight, gestational age, and several other variables controlled, intrapartum fetal death rates decreased as intensiveness of care increased. Compared with births in Level 3 maternity units (perinatal intensive care), births in Level 1 units (community hospitals) had a 61% excess risk of intrapartum fetal death (p less than 0.01) and births in Level 2 units (intermediate level of care) had a 35% excess risk (p = 0.06). The effect of hospital level on intrapartum fetal death rates could not be attributed to differences in the classification of fetal deaths during labor across hospital levels, since no compensatory differences in late antepartum fetal death rates were found. Our findings in a total population are compatible with several studies carried out in single hospitals that have reported declines in intrapartum fetal death rates, especially in births more closely attended during labor. Fetal deaths that occur in labor, as contrasted with fetal deaths occurring before labor, constitute a perinatal outcome that is especially sensitive to level of obstetric care.

Declining perinatal mortality in a region of Finland, 1968-82

Perinatal mortality (PNM) in the catchment area of the University Central Hospital of Turku (UCHT), Finland, was investigated during a 15-year period from 1968 to 1982. During the study period, 82,151 babies were born, there were 531 fetal deaths and 505 cases of early neonatal death. The PNM rate declined during the study period from 17.9 in 1968 to 7.0 in 1982, or from 14.8 to 4.6 when infants weighing less than 1000 grams were excluded. Significant declines occurred in PNM due to maternal illness, placental and umbilical cord complications, other asphyxias and respiratory distress syndrome. We believe the centralization of obstetric and neonatal services for risk cases, the introduction of modern obstetric and neonatal management, and continuing education of personnel at every level of maternity and neonatal care accounted for the decline.