Mortality after 36 weeks postmenstrual age of extremely preterm infants in neonatal care: The impact of growth impairment and bronchopulmonary dysplasia.

ABSTRACT

BACKGROUND: A small group of extremely preterm infants survive to 36 weeks postmenstrual age (PMA), but die before discharge from neonatal care. AIMS: To investigate which epidemiological and clinical parameters were related to death after 36 weeks PMA in extremely preterm infants. STUDY DESIGN: Retrospective whole-population study. SUBJECTS: All infants born <28 weeks of gestation admitted to a neonatal unit in England between 2014 and 2018. OUTCOME MEASURES: Mortality after 36 weeks PMA and before discharge from neonatal care. Bronchopulmonary dysplasia (BPD) defined as any respiratory support at 36 weeks PMA. RESULTS: Death after 36 weeks PMA occurred in 156 of a total of 11.747 included infants (1.3 %) and at a median (IQR) age of 130 (93-164) days. A lower gestational age [Odds Ratio 0.82, 95 % CI0.72-0.94, adjusted p = 0.005], lower birth weight z-score [Odds Ratio 0.45, 95 % CI0.36-0.56, adjusted p < 0.001], greater absolute difference in weight z-score from birth to 36 weeks PMA [Odds Ratio 0.46, 95 % CI0.38-0.56, adjusted p < 0.001] were independently associated with death after 36 weeks PMA. A diagnosis of BPD [Odds Ratio 4.57, 95 % CI2.19-9.54, adjusted p < 0.001] and of necrotising enterocolitis requiring surgery [Odds Ratio 2.81, 95 % CI1.82-4.34, adjusted p < 0.001] were also independently associated with death after 36 weeks PMA. CONCLUSIONS: Mortality of extremely preterm infants after 36 weeks postmenstrual age is associated with lower gestational age and more impaired growth. The diagnoses of bronchopulmonary dysplasia and necrotising enterocolitis were associated with a higher risk of death after 36 weeks postmenstrual age and before discharge from neonatal care.