Characteristics of Heart Rate Tracings in Preterm Fetus.

Maria F Hurtado-Sánchez,Juan Mozas-Moreno,David Pérez-Melero,Ernesto González-Mesa,Alberto Puertas-Prieto,Andrea Pinto-Ibáñez

doi:10.3390/medicina57060528

Abstract

Background and Objectives: Prematurity is currently a serious public health issue worldwide, because of its high associated morbidity and mortality. Optimizing the management of these pregnancies is of high priority to improve perinatal outcomes. One tool frequently used to determine the degree of fetal wellbeing is cardiotocography (CTG). A review of the available literature on fetal heart rate (FHR) monitoring in preterm fetuses shows that studies are scarce, and the evidence thus far is unclear. The lack of reference standards for CTG patterns in preterm fetuses can lead to misinterpretation of the changes observed in electronic fetal monitoring (EFM). The aims of this narrative review were to summarize the most relevant concepts in the field of CTG interpretation in preterm fetuses, and to provide a practical approach that can be useful in clinical practice. Materials and Methods: A MEDLINE search was carried out, and the published articles thus identified were reviewed. Results: Compared to term fetuses, preterm fetuses have a slightly higher baseline FHR. Heart rate is faster in more immature fetuses, and variability is lower and increases in more mature fetuses. Transitory, low-amplitude decelerations are more frequent during the second trimester. Transitory increases in FHR are less frequent and become more frequent and increase in amplitude as gestational age increases. Conclusions: The main characteristics of FHR tracings changes as gestation proceeds, and it is of fundamental importance to be aware of these changes in order to correctly interpret CTG patterns in preterm fetuses.

Highlights

Cardiotocography (CTG) aims to identify fetal heart rate (FHR) patterns that may indicate a risk, so that clinicians can forestall problems with measures intended to improve perinatal outcomes
With their less developed parasympathetic system, usually have a higher baseline FHR compared to term or postterm fetuses, with their more developed parasympathetic system
Despite the absence of standards for determining which characteristics of CTG tracings or FHR patterns can be considered unequivocally normal for preterm fetuses, what little evidence has accumulated to date shows clear differences in FHR patterns between preterm and term fetuses, and these differences must be taken into account to ensure that the patterns are evaluated appropriately

Summary

Introduction

Cardiotocography (CTG) aims to identify fetal heart rate (FHR) patterns that may indicate a risk, so that clinicians can forestall problems with measures intended to improve perinatal outcomes. As a tool with high sensitivity but very low specificity, the false positive rate of CTG findings approaches 60%. The lack of reference standards for CTG patterns in preterm fetuses can lead to misinterpretation of the changes observed in electronic fetal monitoring (EFM). The aims of this narrative review were to summarize the most relevant concepts in the field of CTG interpretation in preterm fetuses, and to provide a practical approach that can be useful in clinical practice. Results: Compared to term fetuses, preterm fetuses have a slightly higher baseline FHR

Methods

Results

Conclusion