Evaluation of newborns with Down syndrome with weight less than 1500 g in the neonatal intensive care unit: A Japanese multicentre study

Aim This study aimed to clarify the characteristics and their mortality‐related factors in very low birthweight infants with Down syndrome (DS) in Japan. Methods This retrospective case–control study enrolled newborns with DS weighing <1500 g admitted to neonatal intensive care unit (NICU) of the perinatal centre registered with the Neonatal Research Network of Japan (NRNJ) database from 2008 to 2019. The clinical characteristics and their mortality‐related factors were compared among the Dead group (newborns with DS who died in the NICU), the Survival group (newborns with DS who were alive from the NICU) and the Control group (newborns without congenital or chromosomal condition). Results A total of 53 656 newborns weighing <1500 g were registered in the NRNJ database for 12 years. Of these, 310 (0.6%) were diagnosed with DS: 62 newborns in the Dead group, 248 in the Survival group and 49 786 in the Control group without chromosomal condition. Logistic analysis revealed that there was a significant difference in the mortality‐related factors in congenital anomalies, pulmonary haemorrhage and persistent pulmonary hypertension of the newborn; the adjusted odds ratios were 8.6, 121 and 9.5, respectively. Newborns with DS weighing <1000 g showed the earliest death in the NICU on the Kaplan–Meier survival curve ( P < 0.01). Conclusion The mortality rate for newborns with DS weighing <1500 g was 20% (5% in the Control group). The mortality‐related factors were complications of congenital anomalies, pulmonary haemorrhage and persistent pulmonary hypertension of the newborn.