Characteristics of Heart Rate Tracings in Preterm Fetus

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.

Differences in the Asymmetry of Beat-to-Beat Fetal Heart Rate Accelerations and Decelerations at Preterm and Term Active Labor

“…Thus, we hypothesize that fetuses during moderate premature labor might exhibit a different response to stress during active labor than term fetuses. The findings presented here are in line with those of Hurtado-Sánchez et al, who reported that preterm fetuses manifested slightly higher FHR and lower amplitude decelerations compared to term fetuses evaluated by cardiotocography [40].…”

Correlations of Placental Histopathology, Neonatal Outcome, and Cardiotocogram Baseline Variability and Acceleration Patterns in the Growth Restricted Preterm Population

“…Adequate CTG evaluation of a preterm fetus is a problematic issue in perinatology, as the lack of guidelines and evidence-based recommendations make it complicated. 19 Baseline fetal heart rate in preterm fetuses is often tachycardiac (>160 bpm) 7 and decelerations-especially in the early preterm (24-28 weeks) population-can be found more often and could be normal compared to term fetuses. 20 In our study, baseline variability pattern and absence of accelerations were studied to determine the reassuring or non-reassuring nature of cardiotocograms in the light of neonatal parameters after birth, with the concurrent study of the corresponding placental histopathological changes.…”

“…Adequate CTG evaluation of a preterm fetus is a problematic issue in perinatology, as the lack of guidelines and evidence-based recommendations make it complicated. 19 Baseline fetal heart rate in preterm fetuses is often tachycardiac (>160 bpm) 7 and decelerations—especially in the early preterm (24-28 weeks) population—can be found more often and could be normal compared to term fetuses. 20…”

“…6 CTG monitoring of preterm fetuses does not have reference standards and well-defined guidelines in contrast with the CTG interpretation of term fetuses. 7 CTG interpretation in the early preterm (between the 24th and 28th weeks of pregnancy) population is especially characterized by inadequate monitoring 8 and lack of evidence.…”

Paradigm Shift Between Micro Biota & Micro Biome: A Key Role in The Adaptation of Mammals to Their Diverse Lifestyles

“…A baseline fetal heart rate status: normal between 110 to 160 bpm, Tachycardia >160 bpm, bradycardia <110 bpm [28].…”