Comparison of Clinical Outcomes in Late Preterm Infants between Born at 34+0 to 34+6 Weeks and at 35+0 to 36+6 Weeks of Gestation

Purpose: We compared perinatal characteristics, clinical outcomes, and treatment between late preterm infants born at 34 weeks and 35 to 36 weeks of gestation. Methods: We reviewed the medical records of 254 neonates (gestational age 34 to 36 weeks) who were born at Inje University Sanggye Paik Hospital between July 1, 2013 and June 31, 2018. Late preterm infants were categorized into two groups: Group 1 (born at 34 weeks, n=88) and Group 2 (born at 35 to 36 weeks, n=162). We compared the clinical outcomes, treatment, and readmission within 12 months after birth between two groups. Results: Group 1 showed higher frequencies of antenatal steroid administration, prema­ ture membrane rupture, maternal antibiotic use, and histologic chorioamnionitis. Group 1 also had significantly more medical problems such as respiratory distress, feed ing intolerance, gavage feeding, neonatal jaundice, apnea or bradycardia, and hypocalcemia. Treatment during hospital stay including respiratory support, nutritional sup port, and antibiotics use over 24 hours was also significantly higher in Group 1. In addition, delayed discharge was more frequent in Group 1. Conclusion: Late preterm infants born at 34 weeks gestation had significantly higher morbidity, required more aggressive management, and more often had delayed dis­ charge compared to those in late preterm infants born at 35 to 36 weeks’ gestation.