The prediction and prevention of intrapartum fetal asphyxia in preterm pregnancies

Electronic fetal monitoring in the United States: temporal trends and adverse perinatal outcomes

OBJECTIVE

To examine trends in electronic fetal monitoring (EFM) use and quantify the extent to which such trends are associated with changes in rates of primary cesarean delivery and neonatal morbidity and mortality.

METHODS

We carried out a retrospective study of more than 55 million nonanomalous singleton live births (24-44 weeks of gestation) delivered in the United States between 1990 and 2004. Changes in the risks of neonatal mortality, cesarean delivery, and operative vaginal delivery for fetal distress, 5-minute Apgar score lower than 4, and neonatal seizures (at 34 weeks of gestation or after) were examined in relation to changes in EFM use.

RESULTS

Electronic fetal monitoring use increased from 73.4% in 1990 to 85.7% in 2004, a relative increase of 17% (95% confidence interval 16-18%). This increase was associated with an additional 5% and 2% decline in early and late neonatal deaths, respectively, at 24-33 weeks of gestation as well as a 4-7% additional decline in the 5-minute Apgar score lower than 4 at 24-33, 34-36, and 37-44 weeks of gestation. Increasing EFM use was associated with a 2-4% incremental increased rate of both cesarean delivery and operative vaginal delivery for fetal distress at 24-33, 34-36, and 37-44 weeks of gestation. Increasing EFM was not associated with any temporal changes in the rate of neonatal seizures.

CONCLUSIONS

The temporal increase in EFM use in the United States appears to be modestly associated with the recent declines in neonatal mortality, especially at preterm gestations.

LEVEL OF EVIDENCE

II.

Electronic fetal heart rate monitoring and its relationship to neonatal and infant mortality in the United States

OBJECTIVE

To examine the association between electronic fetal heart rate monitoring and neonatal and infant mortality, as well as neonatal morbidity.

STUDY DESIGN

We used the United States 2004 linked birth and infant death data. Multivariable log-binomial regression models were fitted to estimate risk ratio for association between electronic fetal heart rate monitoring and mortality, while adjusting for potential confounders.

RESULTS

In 2004, 89% of singleton pregnancies had electronic fetal heart rate monitoring. Electronic fetal heart rate monitoring was associated with significantly lower infant mortality (adjusted relative risk, 0.75); this was mainly driven by the lower risk of early neonatal mortality (adjusted relative risk, 0.50). In low-risk pregnancies, electronic fetal heart rate monitoring was associated with decreased risk for Apgar scores <4 at 5 minutes (relative risk, 0.54); in high-risk pregnancies, with decreased risk of neonatal seizures (relative risk, 0.65).

CONCLUSION

In the United States, the use of electronic fetal heart rate monitoring was associated with a substantial decrease in early neonatal mortality and morbidity that lowered infant mortality.

Development and significance of a fetal electrocardiogram recorded by signal-averaged high-amplification electrocardiography

Although ultrasonic diagnostic imaging and fetal heart monitors have undergone great technological improvements, the development and use of fetal electrocardiograms to evaluate fetal arrhythmias and autonomic nervous activity have not been fully established. We verified the clinical significance of the novel signal-averaged vector-projected high amplification ECG (SAVP-ECG) method in fetuses from 48 gravidas at 32-41 weeks of gestation and in 34 neonates. SAVP-ECGs from fetuses and newborns were recorded using a modified XYZ-leads system. Once noise and maternal QRS waves were removed, the P, QRS, and T wave intervals were measured from the signal-averaged fetal ECGs. We also compared fetal and neonatal heart rates (HRs), coefficients of variation of heart rate variability (CV) as a parasympathetic nervous activity, and the ratio of low to high frequency (LF/HF ratio) as a sympathetic nervous activity. The rate of detection of a fetal ECG by SAVP-ECG was 72.9%, and the fetal and neonatal QRS and QTc intervals were not significantly different. The neonatal CVs and LF/HF ratios were significantly increased compared with those in the fetus. In conclusion, we have developed a fetal ECG recording method using the SAVP-ECG system, which we used to evaluate autonomic nervous system development.

Cesarean section and the outcome of very preterm and very low-birthweight infants

Births of extremely preterm infants, less than 26 weeks' gestation, by cesarean section have increased significantly in the United States over the past decade. The justification for this increase is not well supported in the literature. This review examines recent analyses that suggest there may be some survival advantage for infants less than 26 weeks delivered by cesarean section. The appropriateness of intervening with cesarean sections for these very immature infants, however, remains uncertain.

Critical illness during pregnancy: considerations for evaluation and treatment of the fetus as the second patient

When a critically ill woman is pregnant, clinical interventions for the mother can have a profound effect on fetal status. It is essential that the fetus be considered as the second patient when developing the plan of care. The most practical solution for providing comprehensive care to pregnant women in the intensive care unit (ICU) is a collaborative approach involving members of the ICU and the perinatal team, each contributing their unique knowledge and skills to the care of the mother and her unborn baby. The purpose of this article is to describe a collaborative approach to caring for a pregnant woman in the ICU along with a brief overview of fetal assessment for ICU care providers so they can become familiar with terms and methods used in assessing fetal status and common interventions that promote fetal well-being.

The Current Crisis in Obstetrics

Of the issues leading to legal actions in obstetrics, the most important are events occurring before delivery that are deemed to account for the birth of a physically or mentally challenged child. In determining causation in the clinical setting, the diagnosis of fetal asphyxia can be made using blood gas and acid-base assessment. However, there are many subsidiary questions that in most cases cannot be answered, including when the asphyxia began, the severity and nature of the asphyxia during the exposure, the quality of the cardiovascular compensation, and when the brain damage occurred. When scientific proof is not available, the dilemma for the court is the requirement to reach a conclusion about the timing of brain damage on the balance of probabilities. Although it is of value, clinical risk scoring using fetal heart rate (FHR) monitoring may result in false positive predictions of fetal asphyxia. The problem in FHR monitoring is the lack of a detailed algorithm for the interpretation of FHR patterns with appropriate recommendations for management. Until such an algorithm is developed, health care workers cannot be expected to respond to fetal heart rate patterns consistently. Responsibility for the crisis in obstetrics must rest with the members of the health care disciplines who provide expert testimony. Progress made in research encourages us to assume that more is known about the causes of brain damage in the clinical setting than in fact is known. Similarly, health care professionals, parents, and lawyers often assume current methods of prediction and diagnosis to be more effective than they actually are.

Intrapartum Assessment of the Fetus: Historical and Evidence-Based Practice

The principal purpose of intrapartum fetal assessment is to detect hypoxemia-ischemia, which may lead to fetal jeopardy. A quarter century ago, electronic fetal monitoring replaced intermittent auscultation as the primary method of intrapartum fetal assessment in the United States. It seems that electronic fetal monitoring will continue to be the primary mode of intrapartum fetal assessment, with intermittent auscultation used in some centers primarily for low-risk parturients. From this abridged history of intrapartum fetal monitoring, it is recognized that all surveillance methods bear inherent limitations.