Camarinha, CatarinaOliveira, Maria MiguelNobre, Miguel de AraújoFurtado, CristinaElias, CecíliaBacelar-Nicolau, LeonorCosta, Andreia SilvaNogueira, Paulo Jorge2026-06-052026-06-052026-04-0455f17690-cfd4-4971-8599-8b4294faf4a4http://hdl.handle.net/10400.14/57976This study aimed to estimate Severe Maternal Morbidity (SMM) rates and trends among public hospital deliveries in Portugal, 2010–2018, and identify associated factors. A register-based observational crosssectional study was conducted using public hospital admission delivery episodes. SMM was identified using the Centers for Disease Control and Prevention (CDC) indicators. Descriptive statistics, Mann– Kendall trend test, binary logistic regression and adjusted logistic regression were used to assess trends and associated factors. Between 2010 and 2018, 8,854 delivery episodes met the criteria for SMM. Blood transfusion, acute renal failure, and shock showed the highest increase in rate per 1,000 hospitalized deliveries. SMM rate was 13.14 per 1,000 deliveries and 3.22 per 1,000 deliveries without blood transfusion. Maternal age (≥40 years adjusted odds ratio (OR) 1.38, 95% confidence intervals (CI) 1.09–1.66), hospitalized days (adjusted OR 1.04, 95% CI: 1.04–1.05), number of diagnoses (adjusted OR 1.27, 95% CI 1.25–1.28) and procedures during hospitalization (adjusted OR 1.26, 95% CI 1.24–1.27), and International Classification of Diseases, 10th edition, Clinical Modification and Procedure Coding System (ICD-10-CM/PCS) (adjusted OR 1.63, 95% CI: 1.08–2.18) were significantly associated with a higher risk of SMM. After 2015, the risk of SMM decreased. SMM with blood transfusion was positively associated with hospitalization days, number of diagnoses, procedures, residing in Algarve, Alentejo or Centro, and ICD-10-CM/PCS. Trends in SMM between 2010 and 2018 in Portugal show an increase, particularly for blood transfusion. Risk factors included age, hospitalization length, intensity of diagnoses and procedures, and ICD-10-CM/PCS coding.engDelivery hospitalizationsMaternal healthSevere maternal morbidityresearch article10.1038/s41598-026-42363-910504021679241935110001776252600015