The effect of birth weight on early morbidities and rehospitalization in late preterms

Premature births are the most important determinant of neonatal mortality and morbidity. Although late preterm babies are thought to be mature due to their better birth weight and activity compared to other premature groups, they have increased mortality, morbidity and readmission rates due to their immaturity. There is limited data in the literature regarding the effect of birth weight on morbidity and rehospitalization in late preterms. Existing studies have focused on small for gestational age (SGA) babies, and there are no studies on large for gestational age (LGA) babies. This study aimed to determine the early morbidity and rehospitalization rate of live-born babies at 340/7-366/7 gestational weeks in our hospital and to determine the effect of birth weight on morbidity and rehospitalization. The files of patients born in our hospital between 01.01.2019 and 01.01.2022 were retrospectively examined through the hospital electronic data system. A total of 547 babies, 78 (%14.3) SGA, 381 (%69.7) AGA and 88 (%16) LGA were included in the study. Transient tachypnea of the newborn (TTN) occurred in 173 of these babies (%31.6), pneumonia in 44 (%8), respiratory distress syndrome in 18 (%3.3), apnea in 39 (%7.1), feeding intolerance in 199 (%36), hypoglycemia in 181 (%33.1), jaundice in 165 (%30.2), polycythemia in 58 (%10.6) and hypothermia in 25 (%4,6) was detected. When morbidity data were examined according to birth weight, the incidence of hypothermia and pneumonia was found to be higher in SGA than in AGA. The rate of apnea and feeding intolerance was higher in SGAs than in AGAs and LGAs, and the average IV fluid/TPN duration and time to transition to total enteral nutrition were longer. The incidence of hypoglycemia, polycythemia, hyperbilirubinemia, and NICU admission rate were higher in SGA and LGAs than in AGA babies; oxygen, non-invasive respiratory support, total respiratory support and hospital stay were longer. The rate of TTN and feeding intolerance was higher in LGAs compared to AGA babies, and the average time to transition to total oral feeding was longer. Of the 508 babies whose rehospitalization data could be accessed by phone, 152 (%29.9) required rehospitalization up to a corrected age. Among the reasons for hospitalization, the most common hospitalization diagnoses were hyperbilirubinemia with a rate of %41.4, infections with a rate of %25.7 and surgical reasons with a rate of %15.1. When rehospitalization data were examined according to birth weight, there was no significant difference between the groups in terms of hospitalization rates up to one corrected age, but the reason for rehospitalization differed between the groups. The rate of hospitalization due to nutritional problems was found to be higher in SGA patients than in AGA patients, and the rate of hospitalization due to jaundice was lower. As a result, late preterm infants face various morbidities both in the early period and in the first year of life. In this study, in addition to being late preterm SGA, being late preterm LGA was also associated with increased morbidity rates.