The Impact Of The Natural Menstrual And Hormonal Contraceptive Cycle On Brachial Artery Endothelial Function In Healthy Premenopausal Females.
Bibliographic record
Abstract
BACKGROUND & PURPOSE: Oral contraceptive pills (OCPs) are the most common prescription for premenopausal women, with four generations of OCPs developed, each of which differs in synthetic estrogen and progestin dose and type of progestin. Commonly prescribed OCPs include 2nd generation OCPs (OCP2) containing levonorgestrel and 3rd generation OCPs (OCP3) containing desogestrel or norgestimate. Similar to phasic fluctuations in endogenous estrogen and progesterone in the natural menstrual cycle (NAT), OCP cycles include active (i.e., containing synthetic hormones) and placebo pill phases. Previous research has identified that NAT and/or OCP cycle phases may influence brachial artery endothelial function; however, research is limited, and findings are mixed. Therefore, the purpose of this study was to investigate the influence of NAT, OCP2, and OCP3 cycles on brachial artery endothelial function. METHODS: Forty-nine premenopausal females (n = 17 NAT, n = 17 OCP2, n = 15 OCP3) took part in two experimental visits in the low (LH: early follicular/placebo) and high (HH: mid-luteal/active) hormone phases of the hormonal cycle, in a randomized order. Brachial artery endothelial function was assessed using a reactive hyperemia flow mediated dilation (FMD) test, represented as percent (%FMD) changes in artery diameter. A linear mixed model ANOVA with factors group (NAT, OCP2, OCP3) and phase (LH, HH) was used to examine potential differences in baseline diameter and %FMD. RESULTS: Endothelial function (%FMD) was elevated in the HH phase compared to the LH phase, regardless of group [HH: 7.7 ± 3.5%, LH: 7.0 ± 3.3%, p = 0.02, Cohen’s d = 0.18 (small effect)]. Brachial artery baseline diameter was lower in HH compared to LH [HH: 3.50 ± 0.40, LH: 3.53 ± 0.41, p = 0.04, Cohen’s d = 0.08 (small effect)]. The phasic difference observed in %FMD was no longer significant after differences in baseline diameter were controlled for (p = 0.06). CONCLUSIONS: Natural and hormonal contraceptive cycle phases do not appear to influence brachial artery endothelial function but may have a small influence on basal vascular tone. This research challenges the notion that the hormonal cycle phases must be controlled for in vascular physiology research, potentially reducing a perceived barrier to the inclusion of female participants in future studies.
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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 | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".