THE INFLUENCE OF BIRTH ORDER ON BIRTH WEIGHT: DOES THE SEX OF PRECEDING SIBLINGS MATTER?
Bibliographic record
Abstract
The purpose of this study was to investigate whether the well-established relationship between parity and birth weight is affected by the sex composition of siblings, especially for male newborns. Subjects were 856 male and 862 female newborns who weighed at least 2500 g at birth, who were born after 37 completed weeks of gestation, who obtained an Apgar score of 7 or higher, who had the same biological parents as all other children in the sibship, and who lived in the same household. Information on birth weight was collected from hospital records. Results showed that male newborns with older brothers weighed less than male newborns with older sisters. In contrast, the weight of female newborns with older brothers did not differ from the weight of female newborns with older sisters. One explanation of these results is that maternal immunoreactivity to some male-specific feature of the fetus affects prenatal development and consequently reduces birth weight in males. The relation between older brothers and birth weight may have theoretical significance for behavioural variables.
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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 | 0.002 | 0.012 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 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".