Pre-pregnancy body mass index and adverse maternal and perinatal outcomes in twin pregnancies: a population based retrospective cohort study
Bibliographic record
Abstract
Objectives To assess associations between pre-pregnancy BMI and severe maternal morbidity (SMM), perinatal death and neonatal morbidity in twin pregnancies. Design Retrospective cohort study. Setting British Columbia, Canada (2000-2017). Population All twin births at ≥20 weeks’ gestation. Methods We examined associations between pre-pregnancy BMI, categorized as underweight (BMI <18.5m/kg2), normal BMI (18.5m/kg2 BMI <25m/kg2), overweight (25m/kg2 BMI <30m/kg2) and obese (BMI ≥30m/kg2) and adverse maternal and perinatal outcomes, using targeted maximum-likelihood estimation, adjusted for demographics and obstetric history. Outcomes SMM, perinatal death, severe perinatal morbidity. Results Overall, 7770 (368 underweight, 1704 overweight and 1016 obese) women with twin pregnancy were included. The rates of SMM (per 10,000 pregnancies) were: 271.1, 320.4, 270.0 and 225.9 in underweight, normal BMI, overweight and obese women, respectively. Underweight women had higher rates of the composite perinatal adverse outcome (adjusted rate ratio) [aRR] = 1.79, 95%CI = 1.32- 2.43), largely driven by increased rates of severe respiratory distress syndrome, and neonatal death (aRR = 2.81, 95%CI = 1.64-4.83). There was no evidence of elevated risk for perinatal outcomes among overweight and obese women. Conclusions In this population-based study cohort study, we found no evidence of an increased risk of adverse maternal and perinatal outcomes in overweight and obese women with twins; however, infants of underweight women are at higher risk of neonatal death and morbidity. These findings have implications for pregnancy care of women with twin pregnancies, especially those who are underweight. Funding SickKids Foundation (SKF-154852) Keywords: pre-pregnancy obesity, maternal morbidity, perinatal death
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 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) | 0.001 | 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".