The Likelihood of Change in Fetal Presentation During the Third Trimester in Twin Pregnancies
Bibliographic record
Abstract
OBJECTIVE: To estimate the likelihood and identify predictors of spontaneous fetal version during the third trimester in twins using data from a multicenter randomized controlled trial on mode of delivery in twin pregnancies. METHODS: Women with twin pregnancies after 32 weeks of gestation in which twin A was vertex were randomized to planned cesarean or planned vaginal delivery. In the current study we analyzed the likelihood of a spontaneous version of any of the twins between ultrasound assessment at the time of randomization and delivery. RESULTS: A total of 2,603 women were analyzed. Twin A tended to persist in the vertex presentation after 32 weeks of gestation with a spontaneous version rate to nonvertex presentation of 3.0% (95% confidence interval [CI] 2.3-3.7%). Twin B was less stable and underwent spontaneous version in 24.8% (95% CI 23.1-26.5%) of cases; the rate remained higher than 20% even after 34 weeks of gestation. On multivariable analysis, twin A was more likely to undergo version when twin B was smaller (adjusted odds ratio [OR] 2.0, 95% CI 1.04-3.3), when twin B was breech (adjusted OR 3.7, 95% CI 2.2-6.4) or transverse (adjusted OR 2.9, 95% CI 1.6-5.5), and when the interval to delivery exceeded 4 weeks (adjusted OR 2.5, 95% CI 1.3-5.0). Twin B was more likely to undergo version when it was in the breech presentation (adjusted OR 1.7, 95% CI 1.4-2.1) or transverse lie (adjusted OR 3.1, 95% CI 2.5-3.9) compared with vertex presentation, when it was smaller (adjusted OR 1.7, 95% CI 1.1-2.0), when the interval to delivery exceeded 4 weeks (adjusted OR 1.7, 95% CI 1.3-2.4), and in multiparous women (adjusted OR 1.3, 95% CI 1.04-1.5). CONCLUSION: The likelihood of spontaneous version of twin A after 32 weeks of gestation is low when twin A is in the vertex presentation but is much higher for twin B, even late during the third trimester. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00187369. LEVEL OF EVIDENCE: II.
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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 | 0.009 | 0.036 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".