Maternal heart rate patterns in the first and second stages of labor

Abstract

Objective. To analyze typical maternal heart rate (MHR) patterns in the first and second stages of labor. Design. Observational study. Setting. Tertiary care community hospital. Population. Normal term parturients with epidural anesthesia. Methods. Confirmed MHR and uterine activity were simultaneously recorded. The average MHR was analyzed 10 seconds before, as well as at the peak of, each contraction and/or pushing effort. Each woman contributed one datapoint at each time point to the analysis. Main outcome measure. Change in MHR during contractions. Results. First stage: 7.6±2.1 contractions per woman (n=18) were analyzed. Average MHR decreased during contractions: from 83±13 to 74±10bpm; p<0.001). In 56% (10/18) of the women, 'early' type decelerations were seen in at least 50% of contractions. Second stage: 3.5±1.5 contractions per woman. All women (n=15) showed MHR accelerations during every pushing effort (ΔMHR: +35±13bpm; 88±14 to 123±17bpm; p<0.001). MHR was persistently >100bpm in three women (17%) in the first stage, and in four women (27%) in the second stage. Peak MHR >140bpm occurred during pushing in 20%. Conclusion. Decreases in MHR during contractions in the first stage of labor can mimic fetal heart rate (FHR) accelerations as well as early type decelerations. Thus, first stage tracings with a low baseline and early type decelerations may be maternal in origin and FHR should be independently confirmed in such tracings. Because second stage MHR accelerations generally show greater amplitude than FHR accelerations, tracings with repetitive accelerations during contractions (especially when Δ >20bpm) should be considered MHR until proven otherwise.

Misidentification of maternal heart rate as fetal on cardiotocography during the second stage of labor: the role of the fetal electrocardiograph

“…Clinicians should be aware of the characteristic features of MHR that differentiate it from FHR to avoid erroneous false reassurance. A recent study has suggested that tracings with repetitive accelerations during contractions (especially when Δ >20 bpm) should be considered MHR until proven otherwise (11).…”

A comparison of heart rate variability in women at the third trimester of pregnancy and during low-risk labour

“…1). To ensure the proper selection of L-C segments accompanied by uterine contractions, we also identified unequivocal increments of the displayed maternal heart rate because during well-established frequent contractions the haemodynamic adjustments should generally involve a compensation of cardiac output by an increased heat rate [4,5,17]. L-C and L-NC segments were only selected if these segments involve none or few maternal gross movements.…”

“…In this regard, previous studies have mainly focused on changes of the mean maternal heart rate in relation to uterine contractions [2,4,5]. Recently, Suzuki et al assessed maternal HRV during labour using a power spectral analysis to describe beat-to-beat changes associated with the particular presence of uterine contractions.…”

“…Contractions during labour are generally associated with an increased maternal heart rate and mean arterial pressure as well as the subsequent increase in cardiac output resulting from increments in both stroke volume and heart rate [1][2][3][4][5]. The details of how these haemodynamic changes are driven by autonomic adaptations and, moreover, the actual role of the autonomic nervous system (ANS) during pregnancy remain to be fully elucidated [6].…”

Maternal heart rate analysis during labor. Has the time come for computerized analysis?

“…We welcome the article on maternal heart rate (MHR) analysis during labor by van Veen et al (1). Hopefully, this will bring more visibility to the important issue of misidentification of MHR during fetal heart rate (FHR) recording in labor and to new developments in computerized analysis that are underway (2,3).…”