Severe Maternal Morbidity Associated with Hospital NICU Level in Washington State

Rising maternal mortality and severe maternal morbidity (SMM) rates have drawn increasing public health attention. We evaluated patterns of SMM across the Washington State Perinatal Regional Network, in which neonatal intensive care unit (NICU) levels correlate with maternal level of care.

Retrospective cohort study using de-identified patient and hospital-level rates of SMM diagnoses and procedures for all women who delivered at 58 hospitals from October 2015 to September 2016. Data were obtained from the Washington State Comprehensive Hospital Abstract Reporting System, which includes inpatient diagnosis with associated Present on Admission flags, procedure, and discharge information derived from hospital billing systems. Deliveries were stratified by having or not having SMM. For each SMM diagnosis, POA rates were tabulated. Hospital SMM rates (all SMM, transfusion only, and SMM excluding transfusion) were grouped according to their NICU level of care (critical access [CA] and 1-4). Odds ratios and 95% confidence intervals (CI) were calculated.

Of 76,961 deliveries, 908 women (1.2%) had any SMM including 533 with transfusion only and 375 with all other SMM diagnoses/procedures. Rates of SMM were highest at level 1 and level 4 hospitals at 1.3 and 1.5%, respectively. Level 1 and CA hospitals had the highest transfusion rate (1.0%), while level 2, 3, and 4 hospitals had progressively lower rates (0.8, 0.7, and 0.5%, respectively; p < 0.01). Level 4 hospitals had the highest rate of SMM diagnoses/procedures (1.0%). Among SMM diagnoses, the percentage with POA was lowest in level 1/CA hospitals (23%) and similar across level 2, 3, and 4 hospitals (39%).

SMM diagnoses occur most frequently at the centers providing the highest level of care, likely attributable to the regional referral system. However, transfusion rates are increased in level 1/CA hospitals. Efforts to decrease SMM should focus on equipping level 1/CA hospitals with tools to decrease maternal morbidity and improve referral systems.

· SMM occurs most frequently at highest level of care.. · Higher transfusion rates occur at lower care level hospitals.. · Most SMM POA occurs at higher level of care..