Changes in Maternal Heart Rate and Autonomic Regulation following the Antenatal Administration of Corticosteroids: A Secondary Analysis

Abstract

While the effect of antenatally administered corticosteroids on fetal heart rate (HR) and heart rate variability (HRV) is well established, little information is available on how these drugs affect maternal physiology. In this secondary analysis of a prospective, observational cohort study, we quantify how corticosteroids affect maternal HR and HRV, which serve as a proxy measure for autonomic regulation. Abdominal ECG measurements were recorded before and in the five days following the administration of betamethasone—a corticosteroid commonly used for fetal maturation—in 46 women with singleton pregnancies. Maternal HR and HRV were determined from these recordings and compared between these days. HRV was assessed with time- and frequency-domain features, as well as non-linear and complexity features. In the 24 h after betamethasone administration, maternal HR was significantly increased (p < 0.01) by approximately 10 beats per minute, while HRV features linked to parasympathetic activity and HR complexity were significantly decreased (p < 0.01 and p < 0.001, respectively). Within four days after the initial administration of betamethasone, HR decreases and HRV features increase again, indicating a diminishing effect of betamethasone a few days after administration. We conclude that betamethasone administration results in changes in maternal HR and HRV, despite the heterogeneity of the studied population. Therefore, its recent administration should be considered when evaluating these cardiovascular metrics.

Changes in Maternal Heart Rate Variability and Photoplethysmography Morphology after Corticosteroid Administration: A Prospective, Observational Study

“…However, the fact that we see a clear impact of corticosteroids on the outcome measures despite the heterogeneity of the participants increases our confidence that corticosteroids indeed affect maternal physiology. Furthermore, these results largely confirm those of previous work in our group, where we assessed the impact of corticosteroids on mHRV in a similar population, as calculated from abdominal ECG recordings [46]. In this previous work, we performed sub-analyses to explore the impact of additional obstetric medications.…”

“…Note that the measurement on day 1 is taken before the second injection of betamethasone is given; therefore, the increased HR is not a response to pain due to the injection. In recent work, we investigated the effect of corticosteroids on mHRV as determined from abdominal ECG measurements in a smaller group of hospitalized pregnant women [46]. In this previous work, we also found decreased parasympathetic activity along with a 10 bpm increase in HR in the 24 h after betamethasone administration-similar to the results observed in this work [46].…”

“…In this previous work, we performed sub-analyses to explore the impact of additional obstetric medications. We did so by repeating our analysis, first excluding women who received nifedipine, which was the most commonly co-administered medication, and second excluding those using antihypertensives, which are known to affect mHRV [46]. In both cases, the trends in mHRV in the days following betamethasone administration were similar to those observed in the main analyses, which included all participants [46].…”

“…Consequently, it is important to consider how the administration of betamethasone may affect assessments of mHRV in women with pregnancy complications. Although the results on mHRV in this population presented in the literature are conflicting at times-potentially in part due to the influence of obstetric medications such as corticosteroids [10]-on average, pregnancy complications seem to be characterized by increased maternal sympathetic activity and decreased parasympathetic activity [44][45][46]. As corticosteroids seem to not affect sympathetic activity (see LF, Figure 5), likely, the increased sympathetic activity as captured by mHRV in complicated pregnancies is accurate.…”

“…In recent work, we investigated the effect of corticosteroids on mHRV as determined from abdominal ECG measurements in a smaller group of hospitalized pregnant women [46]. In this previous work, we also found decreased parasympathetic activity along with a 10 bpm increase in HR in the 24 h after betamethasone administration-similar to the results observed in this work [46]. As vital signs such as maternal HR inform clinical decision-making [47][48][49], clinicians need to consider recent corticosteroid administration when evaluating maternal tachycardia.…”