Infant Mortality in Norway: A Population‐Based Study From 2009 Through 2020

AIM: To explore trends and main causes of infant mortality in Norwegian live-born infants (LBIs) from 2009 through 2020 and assess how trends differ by gestational age (GA). METHODS: Population-based cohort study of infant deaths using data from the Medical Birth Registry of Norway and the Norwegian Cause of Death Registry. RESULTS: The study population consisted of 676 931 LBIs (48.6% female), of which 1583 (2.3 per 1000 LBIs) died in infancy (43% female). There was a linear decline in the infant mortality from 2.9 to 1.7 per 1000 LBIs (p < 0.001). Age of death remained stable; 70% occurred in the neonatal period and 30% occurred within the first 24 h. The main causes of death were in descending order: prematurity-related (39.6%), malformations/chromosomal abnormalities (27.0%), asphyxia/neonatal encephalopathy (12.4%), other (11.0%), SIDS (6.8%) and infections (3.2%). The highest mortality rate, and the most pronounced decline, was observed among extremely preterm infants (below 28 weeks), declining from 363 to 227 per 1000. CONCLUSION: The infant mortality rate declined by more than 40% from 2009 to 2020. Around 70% of all infant deaths occurred in the neonatal period. Prematurity-related mortality was the most common cause of death but showed the greatest decline.