A fetal weight reference for twins based on ultrasound measurements
Bibliographic record
Abstract
Background and ObjectiveFetal growth and size are known indicators of perinatal health, although the etiology of this relationship is unclear, and twins are known to differ from singletons with respect to fetal growth trajectories over the course of pregnancy. With a lack of research on ultrasound-based fetal weight references in twin populations, this study aimed to construct ultrasound-based in utero fetal weight references for each gestational age for a twin population.MethodsTwins delivered at a tertiary care hospital in Montreal were used in this study. Fetal weight was calculated using a published formula that was validated in this population. Fetal growth was then modeled in twins using serial ultrasound measurements of fetal weight, and adjusting for sex and chorionicity. Linear mixed models were used to adjust for the correlation between twins from the same pregnancy, and for the use of multiple ultrasound measurements for each fetus. Restricted cubic splines were used to account for the non-linear growth of fetuses over the course of pregnancy. Predictions were made from this regression model for the 1st, 10th, 50th, 90th and 99th fetal weight percentiles for the gestational period between weeks 22 and 37.ResultsMedian gestational age at birth was 37 weeks, with a predicted median birth weight of 2686 g. The rate of change in fetal weight was observed to be S-shaped over the course of pregnancy, with a period of accelerated growth in the second trimester, and slower growth in the third trimester. Ultrasound-based fetal weight references constructed from this population corroborated other published ultrasound-based fetal weight references in twin populations. As expected, fetal weight in twins was consistently lower than singletons over the course of pregnancy, when compared with other published fetal weight references.ConclusionsThe ultrasound-based fetal weight reference and predicts fetal weight at each gestational age, estimates which could be used to assess fetal size at each gestational age in twin pregnancies. This study additionally validates the use of formulae to estimate fetal weight in a twin population, and adds to literature published in this field.
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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 | 0.004 | 0.022 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.004 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| 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".