(15) National Trends in the Timing and Causes of Death of Periviable Preterm Infants in the United States, 2007- 2021

Background: The causes and timing of death in periviable preterm infants have not been extensively studied.

Objectives: We examined the trends in the causes and the timing of mortality among infants born at 22-23 weeks gestational age (GA) in the United States from 2007-2021.

Design/Methods: This was a retrospective cross-sectional analysis of the linked infant birth/death dataset from the CDC’s WONDER database. We included infants born at 22-23 weeks GA with birthweight < 1000 gm. We used ICD-10 codes to identify causes of death. The exposure variable was the year of death, and the outcomes were the cause- and time-specific crude mortality rate (CMR) through one year of age. The CMR was expressed per 1000 live births and stratified by cause and age at death ( < 1 hour, 1-23 hours, and1-6, 7-27, and 28- 364 days). We evaluated temporal trends with Joinpoint regression and expressed as average annual percentage change (AAPC) with 95% confidence interval.

Results: Of 68,436 preterm infants born at 22-23 weeks GA, 46,259 died within 1 year (CMR 676 per 1000 live births). The CMR was inversely related to the time of death, highest within the first 24 hours (total: 482; < 1 hr 171; 1-23 hrs 312) and lowest at 28-364 days (40). From 2007 to 2021, the CMR declined significantly for infants aged < 1 hr (199 to 116; AAPC -3.9%, CI: -5.1, -2.3%) and 1 - 23 hrs (339 to 240; AAPC -2.4%, CI: -3.1, -1.7%) but increased in infants 7-27 days of age, (62 to 80; AAPC 1.7%, CI: 0.3, 3.1%) (Figure 1). There was no significant change in the CMR for infants aged 1-6 days and 28- 364 days.
The CMR increased significantly for chronic respiratory failure (AAPC 5.6%; CI: 0.3, 25.4%), sepsis (AAPC 2.4%; CI: 0.8%, 4.7%), intraventricular hemorrhage (IVH) [AAPC 6.3%; CI: 1, 20.9%] and necrotizing enterocolitis/intestinal perforation (NEC/SIP) [AAPC 3.2%; CI: 1, 5.4%]. The causes of death varied with age (Figure 2). The CMR for acute respiratory distress/failure, IVH, and pulmonary hemorrhage peaked at age 1-6 days while sepsis and NEC/SIP peaked at age 7-27 days. The CMR for chronic respiratory failure peaked at 28-364 days.

Conclusion: The CMR at 22 to 23 weeks GA was high and was inversely related to age. The decrease in CMR with time suggests improvements in survival, which was associated with increases in some of the causes of death. This data could guide family counseling and future research on the care and the circumstances of death of these infants