A Regional Cohort Study Examining Causes and Trends in Early Neonatal Death Over 20 Years in Miyazaki, Japan

To determine the causes and trends of early neonatal death over 20 years using a regional database in the regional part of Japan.

In this regional cohort study conducted in Miyazaki Prefecture, Japan, the causes of neonatal deaths were determined through a multidisciplinary regional audit and registered in a database. Data on early neonatal death, defined as neonate birth at ≥ 22 weeks gestational age and death within the first 7 days from birth, were extracted from the database between 2003 and 2022. The causes of early neonatal death were reclassified according to the International Classification of Diseases as perinatal mortality. The major categories were sub-classified into specific causes according to the International Classification of Disease-10. Trends in total early neonatal deaths and each cause were evaluated.

A total of 186 583 live births and 124 early neonatal deaths occurred (0.66 per 1000 births). Among the 105 cases registered in the database, the most common category of early neonatal death was "congenital malformations, deformations, and chromosomal abnormalities" (48.6%), followed by "complications of intrapartum events" (12.4%), "infection" (9.5%), and "low birth weight and prematurity" (9.5%). Trisomy 18 was the most common cause (12.4%). The trends in the incidence of each cause of early neonatal death remained unchanged within the 20-year period.

This study revealed the common causes and trends of early neonatal death in a regional part of Japan. To reduce early neonatal death, a preventive strategy against early neonatal death due to common causes would be required in the future.