Effect of sex, menstrual cycle phase, and monophasic oral contraceptive pill use on local and central arterial stiffness in young adults
Bibliographic record
Abstract
Arterial stiffness is associated with increased cardiovascular disease risk. Previous sex-based investigations of local and central stiffness report inconsistent findings and have not controlled for menstrual cycle phase in women. There is also evidence that sex hormones influence the vasculature, but their impact on arterial stiffness across a natural menstrual (NAT) or oral contraceptive pill (OCP) cycle has been understudied. This study sought to 1) examine potential sex differences in local and central stiffness, 2) compare stiffness profiles between NAT and OCP cycles, and 3) investigate the relationship between duration of OCP use and arterial stiffness. Sex hormone concentrations, β-stiffness index (local stiffness), and carotid-femoral pulse wave velocity [cfPWV (central stiffness)] were assessed in 53 healthy adults (22 ± 3 yr old, 20 men, 15 NAT women, and 18 OCP women). All participants were tested three times: men on the same day and time 1 wk apart, NAT women in menstrual, midfollicular and luteal phases of the menstrual cycle, and OCP women in placebo, early active and late active pill phases. β-Stiffness was higher in men than NAT and OCP women ( P < 0.001), whereas cfPWV was similar between groups ( P = 0.09). β-Stiffness and cfPWV did not differ across or between NAT and OCP cycles ( P > 0.05 for both) and were not associated with duration of OCP use (β-stiffness: r = 0.003, P = 0.99; cfPWV: r = -0.26, P = 0.30). The apparent sex differences in local, but not central, stiffness highlight the importance of assessing both indexes in comparisons between men and women. Furthermore, fluctuating sex hormone levels do not appear to influence β-stiffness or cfPWV. Therefore, these stiffness indexes may need to be assessed during only one cycle phase in women in future investigations. NEW & NOTEWORTHY We observed higher local, but not central, arterial stiffness in men than women. We also demonstrated that there are no differences in arterial stiffness between naturally cycling women and women who use monophasic oral contraceptive pills, and that the duration of oral contraceptive pill use does not influence arterial stiffness.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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".