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.