Predictors of adverse short-term outcomes in late preterm infants

BACKGROUND: Infants born between 34 weeks and 36 weeks and 6 days of gestation are defined as late preterm infants (LPIs), and they account for approximately 74% of all premature births. Preterm birth (PB) remains the leading cause of infant mortality and morbidity worldwide. AIM: To analyse short-term morbidity and mortality and identify predictors of adverse outcomes in late preterm infants. PATIENTS AND METHODS: In this retrospective study, we evaluated adverse short-term outcomes of LPIs admitted to the Intensive Care Unit (ICU), Clinic for Children’s Diseases, University Clinical Center Tuzla, between 01.01.2020 and 31.12.2022. The analysed data included sex, gestational age, parity, birth weight, Apgar score (i.e., assessment of vitality at birth in the first and fifth minutes after birth), and length of hospitalization in NICU, as well as short-term outcome data. Maternal risk factors we observed were: age of mother, parity, maternal morbidity during pregnancy, complications and treatment during pregnancy. LPIs with major anatomic malformations were excluded from the study. Logistic regression analysis was used to identify risk factors for neonatal morbidity among LPIs. RESULTS: We analysed data from 154 late preterm newborns, most of whom were male (60%), delivered by caesarean Sect. (68.2%) and from nulliparous mothers (63.6%). Respiratory complications were the most common outcome among all subgroups, followed by CNS morbidity, infections and jaundice requiring phototherapy. The rate of almost all of the complications in the late-preterm group decreased as gestational age increased from 34 to 36 weeks. Birth weight (OR: 1,2; 95% CI: 0,9 − 2,3; p = 0,0313) and male sex (OR: 2,5; 95% CI: 1,1–5,4; p = 0,0204) were significantly and independently associated with an increased risk for respiratory morbidity, and gestational weeks and male sex were associated with infectious morbidity. None of the risk factors analysed herein were predictors of CNS morbidity in LPIs. CONCLUSION: A younger gestational age at birth is associated with a greater risk of short-term complications among LPIs, thus highlighting the need for increased knowledge about the epidemiology of these late preterm births. Understanding the risks of late preterm birth is critical to optimizing clinical decision-making, enhancing the cost-effectiveness of endeavours to delay delivery during the late preterm period, and reducing neonatal morbidity.