Temporal Trends in Second-Stage Cesarean Birth in Ontario, Canada, 2012–2021
Bibliographic record
Abstract
OBJECTIVE: To characterize trends in the mode of delivery in the second stage of labor, to assess factors associated with second-stage cesarean birth compared with operative vaginal birth, and to evaluate the contribution of these factors to changes in second-stage cesarean birth rates over time among individuals giving birth in Ontario, Canada. METHODS: This was a population-based cohort study of all individuals in Ontario, Canada (2012–2021), with singleton term pregnancies reaching full cervical dilation. Temporal trends were assessed with the Cochran–Armitage test. Modified Poisson regression was used to obtain crude (relative risk [RR]) and adjusted relative risk [aRR] and 95% CIs and to quantify the contribution of maternal, obstetric, fetal, and neonatal factors to temporal variations in second-stage cesarean birth rates. All analyses were stratified by parity. RESULTS: Among 806,645 births included, 26.7% of nulliparous and 6.5% of parous individuals had a second-stage cesarean birth or an operative vaginal birth, with ratios of cesarean to operative vaginal birth of 0.24 and 0.16, respectively. Between 2012–2013 and 2020–2021, second-stage cesarean birth rates increased from 4.8% to 5.8% for nulliparous individuals (P for trend<.001, RR 1.16, 95% CI, 1.08–1.24) and from 0.8% to 1.0% for multiparous individuals (P for trend<.001, RR 1.30, 95% CI, 1.11–1.51), as did ratios of cesarean to operative vaginal birth (nulliparous individuals 0.22–0.27, P<.001; multiparous individuals 0.13–0.18, P<.001). Factors strongly associated with second-stage cesarean birth included macrosomia, previous cesarean birth, elevated body mass index, and care by a midwife or family physician. After adjustment for maternal and obstetric factors, the increase in second-stage cesarean birth rates was largely attenuated (nulliparous individuals aRR 1.04, 95% CI, 0.97–1.11; multiparous individuals aRR 1.04, 95% CI, 0.89–1.21), with obstetric practice factors accounting for the largest proportion of the increase (nulliparous individuals 46.3% of the 16.0% increase; multiparous individuals 48.6% of the 29.6% increase). CONCLUSION: Between 2012 and 2021, second-stage cesarean birth rates and ratios of cesarean to operative vaginal birth increased in Ontario, Canada. Changes in obstetric practices were the primary modifiable drivers of this trend.
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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 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.004 |
| Science and technology studies | 0.001 | 0.001 |
| 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 | 0.000 |
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".