Severe maternal and perinatal–neonatal morbidity associated with planned mode of delivery following a previous cesarean from 2003 to 2021: a population-based cohort study
Bibliographic record
Abstract
BACKGROUND: Worsening neonatal outcomes over time among planned vaginal births following a previous cesarean were reported in Canada; what drove the change remained unclear. OBJECTIVE: We aimed to describe time trends in severe maternal and perinatal-neonatal morbidity associated with a planned vaginal birth vs a repeat cesarean after a previous cesarean delivery and identify risk factors associated with the trends. STUDY DESIGN: This population-based cohort study included all singleton births ≥37 weeks' gestation from Nova Scotia, Canada, April 1, 2003 to March 31, 2021 with 1 previous cesarean and without trial of labor contraindications. Primary outcomes were severe maternal morbidity and severe perinatal-neonatal morbidity. Adjusted risk ratios and 95% confidence intervals were estimated using log-binomial regression, accounting for confounding using inverse probability weighting. RESULTS: Among 12,681 births (4% aged ≥40 years), 5138 (40.5%) had a planned vaginal birth. Among those with a planned vaginal birth vs a repeat cesarean, severe maternal morbidity increased over time, from 5.9 vs 5.0 per 1000 deliveries in 2003-2008 (adjusted risk ratio, 1.13; 95% confidence interval, 0.46-2.8) to 17.3 vs 4.3 per 1000 deliveries in 2015-2021 (adjusted risk ratio, 3.4; 95% confidence interval, 1.38-8.2). In addition, severe perinatal-neonatal morbidity increased over time from 10.6 vs 10.0 per 1000 deliveries in 2003-2008 (adjusted risk ratio, 1.18; 95% confidence interval, 0.60-2.3) to 25.1 vs 17.2 per 1000 deliveries in 2015-2021 (adjusted risk ratio, 1.56, 95% confidence interval, 0.98-2.5). Any oxytocin induction or augmentation of labor increased from 12.1% in 2003-2008 to 37.9% in 2015-2021; its use was strongly associated with severe maternal morbidities in 2015-2021. CONCLUSION: Planned vaginal birth vs a repeat cesarean after a previous cesarean delivery was more strongly associated with severe maternal and perinatal-neonatal morbidity in later years. Oxytocin induction and augmentation increased markedly in this population and could not be ruled out as a factor associated with worsening outcomes.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 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".