Population‐based cohort study of hospital delivery volume, geographic accessibility, and obstetric outcomes

OBJECTIVE: To determine associations between geographic accessibility, delivery volume, and obstetric outcomes. METHODS: Population-based cohort study of linked hospital administrative, census, and geospatial data (2006-2009) from all Canadian jurisdictions except Quebec. Perinatal mortality and major maternal morbidity/mortality were compared across categories of road distance and hospital delivery volume. RESULTS: Among 820 761 mothers delivering 827 504 neonates, travel distance had minimal effect on perinatal mortality. Compared with mothers travelling 0-9 km, the odds of adverse maternal outcomes was decreased for women travelling modest distances (20-49 km, odds ratio, 0.80 [95% confidence interval, 0.75-0.86]), and increased thereafter (50-99 km, 0.99 [0.89-1.10]; 200-299 km, 1.44 [1.10-1.87]; >400 km, 2.22 [1.06-4.63]). Relative to high-volume hospitals (>2500 deliveries/year), adverse maternal outcomes were less likely for hospitals with 1000-2499 (0.90 [0.86-0.95]), and roughly equivalent for hospitals with 200-499 (1.34 [1.22-1.48]) and 500-999 (1.27 [1.17-1.39]) deliveries/year. Odds of perinatal mortality ranged from 1.04 (0.73-1.49; 100-199 deliveries/year) to 1.50 (1.04-2.16; 50-99 deliveries/year); the pattern did not suggest causality. CONCLUSION: Maternal outcomes worsen when travel distance is greater than 200 km, and improve when delivery volume exceeds 1000 deliveries per year.