Body composition in late preterm infants according to percentile at birth

Abstract

Background:The data on body composition of late preterm infants, evaluated according to percentile at birth, are scarce. The study aimed to investigate body composition of late preterm infants, according to percentile at birth, and to compare their body composition with that of term newborns. Methods: A total of 122 (99 appropriate and 23 small for gestational age (SGA)) late preterm infants underwent growth and body composition assessment using an air displacement plethysmography system on the fifth day of life and at term. The reference group was composed of 42 healthy, term, breast-fed infants. results: At birth, appropriate and SGA late preterm infants had lower fat mass and fat-free mass indexes than term newborns. The fat mass and fat-free mass content increased significantly throughout the study, irrespective of percentile at birth. At term, fat mass index, but not fat-free mass index, was higher in both appropriate and SGA late preterm infants than in term newborns. conclusion: Late preterm infants, irrespective of their percentile at birth, show postnatal growth characterized by predominant fat mass accretion. The potential long-term health clinical implications of these findings need to be further elucidated. l ate preterm birth, defined as a birth that occurs between 34 0/7 and 36 6/7 weeks of gestation, has markedly increased during the past two decades, accounting for 70% of all preterm births (1). Late preterm infants have been recognized as a high-risk group due to an increased mortality and morbidity compared with full-term newborn infants (2). In addition, although late preterm birth has been associated with a rapid postnatal catch-up growth within the first months of life (3,4), growth faltering up to 5 y of age has also been reported (5). With regard to body composition, late preterm infants at termcorrected age show a higher fat mass but a lower fat-free mass than full-term infants (3,4).Early life has been recognized as a critical time window for metabolic programming. Hence, concern has arisen regarding the potential implications of these findings on the long-term health outcomes of late preterm infants. Indeed, both early growth pattern and body composition development appear to contribute to the programming process for disease risk in later life (6).While postnatal growth and body composition changes in very preterm infants have been widely investigated, considering percentile at birth (7,8), there is a paucity of data on body composition of late preterm infants, evaluated according to percentile at birth. The aim of our study was to investigate body composition changes from birth to term-corrected age in a cohort of late preterm infants, categorized according to percentile at birth, and to compare their body composition with that of full-term newborns. RESULTSGrowth and body composition at term-corrected age data were available for 122 late preterm infants whose basic characteristics at birth are shown in Table 1. As expected, appropriate for gestational age (AGA) late preterm infants we...

Is Fat Mass Accretion of Late Preterm Infants Associated with Insulin Resistance?

“…On the other hand, it is acknowledged that nutrition accounts only for 50% of the variance in early postnatal growth [21] and, as a result, other factors could contribute to the increased fat mass content at term that has been found also by other authors [3,4,5,6]. …”

“…This study was approved by the institutional review board of the Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Cà Granda Ospedale Maggiore Policlinico, and written informed consent from the infants' parents was obtained. All consecutive newborns admitted to the authors' institution between 2014 and 2015, including those previously enrolled into a previous study [4], were screened for eligibility.…”

“…According to our nutritional procedure, human milk was not fortified. When human milk was unavailable or insufficient, formula feeding was started [4,9]. Infants were fed on demand.…”

“…Late preterm infants exhibit a peculiar postnatal growth pattern with regard to weight gain composition; their body composition is characterized by a major accretion from birth to term in fat mass content, irrespectively of the percentile at birth, that leads to an increase in fat mass content, so that late preterm infants at term show a higher fat mass content than term infants at birth [3,4,5,6]. …”

Does Human Milk Modulate Body Composition in Late Preterm Infants at Term-Corrected Age?

“…Late preterm infants show increased mortality and morbidity compared with full-term newborn infants [2]. It has been reported that the first months of the postnatal life of late preterm infants are characterized by rapid postnatal catch-up growth, and as a result, at term-corrected age, late preterm infants achieve a weight either comparable to or higher than full-term newborns [3,4]. Evidence indicates that early body composition development in these infants is accompanied by a major deposition of fat mass so that, at term-corrected age, increased adiposity irrespective of the percentile at birth has been found.…”