The Effect of Altitude on Birthweight/Length Ratio: A Population-Based Study Over 36 Years in an Altitude Range from Sea Level to 1,700 m
Bibliographic record
Abstract
Klebermass-Schrehof Katrin, Thomas Waldhoer, and Lin Yang. The effect of altitude on birthweight/length ratio: a population-based study over 36 years in an altitude range from sea level to 1,700 m. High Alt Med Biol . 23:90–95, 2022. Objective: The negative effect of altitude on fetal growth has been documented, but it is unknown whether this effect changes over time. We investigated the effect of altitude on infant birthweight/length ratio as well as its potential dependence on gestational age and year of birth in the range from sea level up to 1,700 m (Austria). Materials and Methods: Data on maternal characteristics, infant birthweights, and infant lengths were extracted from all Austrian birth certificates between 1984 and 2019. Results: A total of 2,240,439 birth certificates were identified and analyzed. The effect of altitude on birthweight/length ratio was −2.66 g/cm (95% confidence interval [CI]: −2.77 to −2. 54) per 1,000 m increased altitude in 1984–1986, which decreased to −1.96 g/cm (95% CI: −2.09 to −1.82) in 2017–2019. The effect of altitude on birthweight/length ratio remained constant for preterm infants, which fluctuated around −1.5 g/cm. For term infants, the negative effect of altitude on birthweight/length ratio attenuated from −3 to −1.9 g/cm over time with a stronger decrease for infants born between 41 and 42 compared with those between 37 and 40 weeks of gestation. Conclusion: In summary, our data demonstrate a strong effect of altitude on birthweight/length ratio over 36 years with a smaller effect in recent years and a stronger effect in infants born around term age compared with preterm infants.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".