Severe Neonatal Morbidity Across Gestational Age: Monitoring Infants at High Risk of Mortality

This study aimed to quantify temporal trends in severe neonatal morbidity (SNM) and examine its association with neonatal mortality, stratified by gestational age.

This study included all live births in Sweden from 2007 to 2021. SNM types and subtypes were identified based on diagnoses and procedure codes for births ≥ 22 weeks' gestation, including complications within 27 days. Rates were calculated by gestational age, and temporal changes were assessed using rate ratios (RR) and 95% confidence intervals (CI). Adjusted relative risks (aRR) of neonatal death were also estimated.

From 2007 to 2021, 47,048 (2.8%) cases of SNM were identified, rising from 2.2% in 2007 to 3.6% in 2021, mainly due to increased resuscitation/mechanical ventilation rates across all gestational ages. Infections rose among infants born at ≥ 37 weeks (0.59% in 2007-2011 to 0.77% in 2017-2021, RR 1.30, 95% CI, 1.24-1.37), but declined in those born at 22-31 weeks. Neurological morbidity, especially seizures, slightly increased in term and moderately preterm infants. Except for infants born at 22-27 weeks, neonatal mortality risks among infants with SNM were higher in infants with greater gestational ages.

Despite advances in neonatal care, SNM prevalence in Sweden increased from 2007 to 2021 across all gestational ages.