Hospital factors associated with maternal and neonatal outcomes of deliveries to patients with a previous cesarean delivery: an ecological study

BACKGROUND: Recommendations for deliveries of pregnant patients with a previous cesarean delivery and the type of hospitals deemed safe for these deliveries have evolved in recent years, although no studies have examined hospital factors and associated safety. We sought to evaluate maternal and neonatal outcomes among patients with a previous cesarean delivery by hospital tier and volume. METHODS: We carried out an ecological study of singleton live births delivered at term gestation to patients with a previous cesarean delivery in all Canadian hospitals (excluding Quebec), 2013-2019. We obtained data from the Discharge Abstract Database of the Canadian Institute for Health Information. The primary outcomes were severe maternal morbidity or mortality (SMMM), and serious neonatal morbidity or mortality (SNMM). We used regression modelling to examine hospital tier (tier 4 hospitals being those that provide the highest level of care) and volume; we also identified hospitals with high rates of SMMM and SNMM using within-tier comparisons and comparisons with the overall rate. RESULTS: We included 235 442 deliveries to patients with a previous cesarean delivery; SMMM and SNMM rates were 14.6 per 1000 deliveries and 4.6 per 1000 live births, respectively. Among patients with a parity of 1, SMMM rates were lower in tier 1 hospitals (adjusted incidence rate ratio [IRR] 0.68, 95% confidence interval [CI] 0.52-0.89) and higher in tier 4 hospitals (adjusted IRR 1.41, 95% CI 1.05-1.91) than in tier 2 hospitals; SNMM rates did not differ by hospital tier. Rates of SNMM increased with increasing hospital volume (adjusted IRR 1.02, 95% CI 1.00-1.04) and increasing rates of vaginal birth after cesarean delivery (adjusted IRR 1.02, 95% CI 1.01-1.04). Most hospitals had relatively low SMMM and SNMM rates, although a few hospitals in each tier and volume category had significantly higher rates than others. INTERPRETATION: Adverse maternal and neonatal outcomes among patients with a previous cesarean delivery showed no clear pattern of decreasing SMMM and SNMM with increasing tiers of service and hospital volume. All hospitals, irrespective of tier or size, should continually review their rates of adverse maternal and neonatal outcomes.