Differential regulation of sympathetic neural burst frequency and amplitude throughout normal pregnancy: a longitudinal study
Bibliographic record
Abstract
Sympathetic activation is a hallmark of pregnancy. However, longitudinal assessments of muscle sympathetic nerve activity (MSNA) in pregnancy are scarce and have primarily focused on burst occurrence (frequency) at rest, despite burst strength (amplitude) representing distinct characteristics of sympathetic outflow. Thus, we assessed MSNA burst amplitude distributions in healthy women to determine the impact of normal pregnancy on neural discharge patterns in response to orthostatic stress. Twenty-six women were studied longitudinally during pre-, early- (4–8 wk of gestation), and late (32–36 wk) pregnancy, as well as postpartum (6–10 wk after delivery). MSNA, blood pressure (BP), and heart rate (HR) were measured in the supine posture and during graded head-up tilt (30° and 60° HUT). Mean and median MSNA burst amplitudes were used to characterize burst amplitude distribution. In late pregnancy, women demonstrated smaller increases in HR ( P < 0.001) during 60° HUT and larger increases in systolic BP ( P = 0.043) throughout orthostasis, compared with prepregnancy. The increase in MSNA burst frequency during late- relative to prepregnancy (Late: Δ14[10] vs. Pre: Δ21[9] bursts/min; P = 0.001) was smaller during 60° HUT, whereas increases in burst incidence were smaller in late- relative to prepregnancy throughout orthostasis ( P = 0.009). Nonetheless, median burst amplitude was smaller throughout orthostasis in late compared with prepregnancy ( P = 0.038). Thus, while supine MSNA burst frequency was greater in late pregnancy, increases in burst frequency and strength during orthostasis were attenuated. These smaller, orthostatically induced MSNA increases may reflect natural adaptions of pregnancy serving to prevent sympathetic hyper-reactivity that is common in pathological states.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".