764 - Defining Optimal Body Composition Outcomes at Term Equivalent Age in Infants Born Very Preterm

Poster Number: 764
Publication Number: 764.247

Ariel A.. Salas, University of Alabama School of Medicine, Birmingham, AL, United States; Christoph Binder, Medical University of Vienna/Department of Pediatrics and Adolescent Medicine/Division of Neonatology, Pediatric Intensive Care and Neuropediatrics, Vienna, Wien, Austria; Cornelia Wiechers, Department of Neonatology, University Children`s Hospital, Eberhard Karls University, Tuebingen, Germany, Tuebingen, Baden-Wurttemberg, Germany; Nadja Haiden, Kepleruniversityhospital, Linz, Oberosterreich, Austria; Melanie Gsoellpointner, Medical University of Vienna, Vienna, Wien, Austria; Christoph Fusch, Paracelsus Medical University, Dept. of Pediatrics, Nuremberg General Hospital, Nuremberg, Bayern, Germany; Niels Rochow, Klinikum Nürnberg - Paracelsus Medizinische Universität, Nürnberg, Bayern, Germany

Background: The growth calculator (www.growthcalculator.org) is an innovative tool that accounts for postnatal weight loss and variability in weight gain observed during the first weeks after birth to define an “optimal” growth trajectory target from birth to 44 weeks of postmenstrual age (PMA) in infants born preterm. International studies have not characterized the average fat mass (FM) and fat-free mass (FFM) values of infants who achieve this suggested growth target.

Objective: To determine variability in FM and FFM accretion at 36 weeks PMA or discharge in infants born preterm (32 weeks of gestation or less). We hypothesized that the average FM and FFM values among infants with growth trajectories within the weight target defined by the growth calculator tool would differ from the average FM and FFM values observed in infants with weights above or below the target at 36 weeks PMA.

Design/Methods: In this retrospective cohort study, we analyzed anonymous growth, FM, and FFM data from infants born at 32 weeks of gestation or less in the United States, Canada, Germany, and Austria. Infants included had FM and FFM measurements using air-displacement plethysmography at 36 weeks PMA. To test our hypothesis, we entered anthropometric data obtained at birth and term equivalent age in the ‘growth calculator’ application and determined individualized trajectories for each study participant. Using this information, we analyzed the association of weight, length, head circumference, FM, and  FFM values with the deviation from the target weight.

Results: Nearly 1100 infants were included in this observational study. The average gestational age and birthweight were 29 weeks [IQR, 27-31] and 1155g [SD, 398], respectively. The study population included 49% female infants. The median PMA at the time of FM and FFM measurements was 37 weeks [IQR, 36-40]. Weight gain velocity from birth to term equivalent age in the cohort was 13 g/kg/day (IQR, 12-15). FM and FFM values across gestational age groups and accoding to the difference between actual and target weight at term equivalent age are shown (Figure). At 36 weeks PMA, FM and %FM values were higher and FFM values were lower in infants born at lower gestational ages.

Conclusion(s): Infants born preterm without major morbidities achieve suggested weights at 36 weeks PMA; however, infants born at the lowest gestational ages have higher FM z scores and lower FFM z scores. These findings suggest that the nutritional support provided to this subgroup of infants remains suboptimal to achieving suggested target weights. The Neonatal Network (N2) provided funding for this study.