The Association between Prepregnancy Maternal Body Mass Index and Preterm Delivery
Bibliographic record
Abstract
We investigated the association between prepregnancy maternal body mass index (BMI) and preterm delivery (PTD). The study included 44,421 American women presenting for care in Saint Louis, Missouri between 1990 and 2006. Only singleton gestations were included. The authors examined the associations between categories of BMI with PTD <37 and <34 weeks, respectively. A stratified analysis by subtypes of PTD was also performed. The subtypes of PTD evaluated included spontaneous PTD without preterm premature rupture of membranes (PPROM), PPROM, and indicated PTD. Univariate and multivariable analyses were used to estimate the association between maternal BMI categories and PTD <37 weeks, PTD <34 weeks, and subtypes of PTD. Among women meeting the inclusion criteria, PTD <37 occurred in 4783 (10.8%) and PTD <34 weeks in 1132 (2.5%). Being underweight was associated with increased risks of PTD <37 weeks (adjusted odd ratio [OR] = 1.3, 95% confidence interval [CI]: 1.2, 1.5). Being obese was associated with decreased risks of spontaneous PTD without PPROM <37 weeks (adjusted OR = 0.8, 95% CI: 0.7, 0.9) and increased risk of PPROM <37 weeks (adjusted OR = 1.3, 95% CI: 1.1, 1.6) and PPROM <34 weeks (adjusted OR = 1.4, 95% CI: 1.0, 2.0). Prepregnancy obesity increases the risk of PPROM and decreases risk of spontaneous PTD without PPROM.
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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 | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 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 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".