Using Weight Z-Score Differences Between Birth and Discharge (∆ Z-Score) to Compare and Monitor Nutritional Outcomes in Neonatal Units in Latin America Using the EpicLatino Database. Variables That Are Associated with Poor Growth

Introduction: There are no clear guidelines to support adequate nutrition and growth for our neonates. We have used the difference in weight Z-score medians between birth and discharge (∆ Z-score) to assess the nutritional outcomes in EpicLatino. The ∆ Z-score is often negative, accounting for the desirable fluid contraction at birth that sends the preterm baby usually between 0.5-1 weight Z-score point down the curve. From then on, most researchers accepted a healthy and safe growth parallel to the intrauterine rate. No consensus on the optimal timing for assessment or the ideal growth monitoring tool has been achieved, and an ongoing debate persists on the appropriate terminology to express poor postnatal growth. Methods: We analyzed data from the past 8 years (2015-2022) in surviving home to at least 34 weeks corrected age infants with ≤ 32 weeks gestational age at birth (GA). We conducted a series of statistical comparisons with variables that have been mentioned as potential causes of poor nutrition in the literature. We used the weight ∆ Z-score from birth to discharge as a surrogate for nutrition. We obtained the weight median and interquartile range (IQR) from all the EpicLatino units. We also calculated the correlation between weight ∆ Z-score and gestational age and head circumference (HC) at discharge. Results: There were 480 cases that meet the established criteria. Gestational age at birth, necrotizing enterocolitis (NEC), unit of origin, rupture of membranes (ROM) > 24 hours, temperature at admission, and intraventricular hemorrhage (IVH) were significantly different. There was a negative correlation between ∆ Z-score and corrected gestational age at discharge. Head circumference at discharge also correlated with weight ∆ Z-score. Discussion: There is an important variability in the different units of origin. Also, when looking for risk factors, we confirmed that the characteristics of the study population are determinant to extrauterine growth restriction (EUGR) at discharge. As is known, these associations do not establish causality, some of these variables may identify the challenge of nourishing a sick or very small preterm infant, but the unit of origin variable identifies nutrition policies and practices that can be modified through a quality improvement program.