Serial Physiological Changes DuringPregnancy
Bibliographic record
Abstract
0225 Only a few studies have examined the time course and mechanisms of increases in heart rate and breathing at rest and during exercise in early human pregnancy. This information is urgently needed to provide guidelines to safely prescribe and monitor physical activity throughout pregnancy. PURPOSE: To accurately describe the time sequence of changes in heart rate, ventilation and gas exchange at rest and during exercise in healthy pregnant women. METHODS: Serial testing was conducted on healthy, moderately-active women (n = 11) between the 7th and 20th weeks of pregnancy. Subjects were studied at rest and during steady state cycling at a work rate corresponding to approximately 60% of aerobic working capacity. Measurements included heart rate, breath-by-breath alveolar gas exchange, pH, and circulating levels of progesterone (a known respiratory stimulant). Changes between the 7th and 20th week of gestation were analyzed using a mixed-model linear regression procedure. Comparisons were also made with pre-conceptual data from the same subjects and with measurements in late gestation from earlier studies in this laboratory (J Appl Physiol 88:149, 2000; MSSE 34:S119, 2002). RESULTS: The findings support the hypothesis that the primary changes in autonomic control of heart rate occur prior to the 7th week, with gradual moderate increases thereafter. A partly compensated respiratory alkalosis is also established prior to the 7th week. Further increases in pulmonary ventilation appear to be driven primarily by increases in resting metabolic rate. Plasma progesterone reached only 21% of the level observed in late gestation by the 20th week. CONCLUSIONS: The most important changes in cardio-respiratory control are established prior to the 7th week of pregnancy in preparation to support fetal growth. Factors other than increased circulating progesterone should be investigated as potential causes of resting and exercise hyperpnea during pregnancy. Supported by Ontario Thoracic Society, OTS Block Term Grant Funding and NSERC.
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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 | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".