P20.06: The accuracy of prenatal ultrasound in predicting fetal birthweight in diabetic singleton pregnancies
Bibliographic record
Abstract
Ultrasound-derived estimated fetal weight are used to aid in management of diabetic pregnancies. This study assessed whether variation in the timing of ultrasound in the third trimester affects the accuracy of fetal birthweight prediction in diabetic women. A retrospective cohort study of all singleton pregnancies with type I, II or gestational diabetes was performed. EFW was derived by Hadlock equation. We then used the equation proposed by Mongelli to estimate birthweight. Analyses conducted to examine the association between gestational age at ultrasound and accuracy of estimated birthweight considered accuracy in two formats: a continuous variable representing the difference between estimated and actual birthweight and a categorical variable representing whether estimated birthweight was within 250 g of actual birthweight, underestimated or overestimated by more than 250 g. 971 women were included; 125 (12.8%) had type I diabetes, 114 (11.7%) had type II diabetes, and 732 (75.4%) had gestational diabetes. Ultrasounds performed at 38+0 weeks or greater gestation were the most accurate in predicting actual birthweight. At this time point, the mean difference between estimated and actual birthweight was -30 g (95% CI: -109, – 48). After adjusting for maternal body mass index, maternal smoking, and type of diabetes, accuracy improved as gestational age at ultrasound increased (P = 0.005). The odds of under or overestimating birthweight by more than 250 g were not significantly affected by the timing of the ultrasound. The odds of estimating birthweight to within 250 g of actual birthweight was not different if completed at >=38 weeks relative to 28+0 – 31+6 weeks (OR: 1.24; 95% CI: 0.62 - 2.48). The difference between estimated and actual birthweight decreased the closer the pregnancy was to term. Since the predictive accuracy of ultrasound estimation of birthweight improves with gestational age, growth assessments close to term are more likely to be helpful in delivery planning for diabetic women.
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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 | 0.011 | 0.039 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".