The Influence of Oral Contraceptives on the Autonomic Nervous System
Bibliographic record
Abstract
This thesis aims to determine the effects of oral contraceptives (OC) on resting autonomic function, autonomic reflex activation, and cerebral blood flow (CBF). The first study systematically reviewed the effects of OC on any aspect of autonomic function. A search strategy was applied to several databases, and 6,148 citations were retrieved. Forty studies were included and grouped by measurement of autonomic function investigated. Physiological responses to isolated reflex activation (i.e., the chemoreflex, mechanoreflex and metaboreflex) were influenced by OC; however, the effect of OC on resting autonomic indices and response to autonomic stressors was less consistent. These inconsistencies may be caused by hormone dosage within OC formulations or stressor intensity. The second study investigated the influence of OC on the cardiorespiratory response to metabo- and mechanoreflex activation in the arm and leg. Two minutes of isometric handgrip or plantarflexion exercise-induced similar increases in blood pressure (BP) and ventilation (VE) in both OC and non-OC users (NOC). While both exercise modalities increased VE, neither OC nor NOC exhibited a sustained increase in VE during 3 minutes of arm or leg post-exercise circulatory occlusion. All women increased BP and VE during 3 minutes of arm or leg passive movement. Considering that all women had a cardiorespiratory response to mechanoreflex but not metaboreflex activation, we suggest that the mechanoreflex may drive VE during exercise in women. The final study investigated the influence of OC and the menstrual cycle on CBF and cerebral autoregulation (CA) during 5 minutes of hypercapnia (5%). Regardless of menstrual or pill phase, all women improved high frequency and very low frequency dynamic CA (dCA) during hypercapnia, although low frequency dCA decreased in the high hormone phase of NOC and the low hormone phase of the pill cycle. During hypercapnia, the presence of endogenous hormones attenuated dCA, while the chronic use of exogenous hormones (i.e., OC) chronically attenuated dCA (i.e., when hormones were not present). The findings of this thesis shed light on the complex influence of OC on autonomic function, CBF and different physiological stressors, emphasizing the need for further research to fully elucidate its impact. There is a further need to control for menstrual cycle, OC formulation, dose, progestin generation and/or type when studying factors affecting autonomic physiology.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.008 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.003 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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 source (direct Gemma or distilled Codex), 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".