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Session: Respiration & Pregnancy
Session starts: Thursday 26 January, 10:30
Presentation starts: 11:30
Room: Room 531

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Maretha Bester ()
Rohan Joshi ()
Massimo Mischi ()
Judith van Laar ()
Rik Vullings ()

Abstract:
Background: Maternal autonomic adaptation is essential in facilitating the physiological changes that pregnancy necessitates. Insufficient adaptation is linked to complications such as hypertensive diseases of pregnancy. Consequently, tracking autonomic modulation throughout pregnancy could allow for the early detection of emerging deteriorations in maternal health. Autonomic modulation can be longitudinally monitored by assessing heart rate variability (HRV). Yet, changes in maternal HRV corresponding to normally progressing pregnancy remain poorly understood. Current literature focuses on standard HRV features that inform on the activity of the two autonomic branches, often showing conflicting results. Investigating further characteristics of autonomic regulation may offer clarity on autonomic changes during normal pregnancy. One such characteristic is the responsivity of HR to stimuli, which has been shown to be elevated in complicated pregnancies. Subsequently, we investigate whether the increasing stress of healthily advancing gestation alters the maternal autonomic response. Methods: Multiple ECG measurements (≈45 minutes) were obtained longitudinally from 29 healthy pregnant women (range 14-41 weeks of gestation). Maternal autonomic response was assessed with phase rectified signal averaging (PRSA), which graphically shows the rate and magnitude of HR responsivity. Deceleration capacity (DC), which quantifies the response observed in PRSA, was calculated correspondingly. Results were grouped into three gestational age ranges (i.e. under 23 weeks (GA₁), 23 to 32 weeks (GA₂), and over 32 weeks (GA₃)). Friedman’s test, with a Dunn’s post hoc test and Bonferroni correction, and Cohen’s U₁ were performed to determine the significance and effect sizes of differences between groups, respectively. Results: The median and interquartile ranges of the DC were 11.7 (8.3 – 14.9) for GA₁; 9.5 (5.8 – 12.8) for GA₂, and 8.4 (6.2 – 11.7) for GA₃. Changes across groups were significant (p = 0.002), yet the effect sizes were small (U₁ = 0.05, 0.02 and 0.04, respectively). Conclusion: Autonomic responsiveness dampens under the increasing stress of advancing gestation. This downward trend starts before 20 weeks of gestation, i.e. before the timepoint after which complications are typically diagnosed. Subsequently, longitudinally tracking maternal autonomic response with PRSA may aid in the early detection of complications.