No Relative Increase in Intra-Abdominal Adipose Tissue in Healthy Unstressed Preterm Infants at Term

Abstract

Background: Preterm infants may be at risk for altered adiposity, a known risk factor for unfavorable metabolic and cardiovascular outcomes. Objectives: The aim was to compare body composition (total body fat mass (FM), subcutaneous and intra-abdominal adipose tissue (AT)) between infants born preterm and at term. Methods: We conducted an observational, cross-sectional study that involved 50 infants born preterm free from major co-morbidities and 34 term healthy breastfed infants. Anthropometric measurements, body composition (total body FM, subcutaneous and intra-abdominal AT) were assessed at 40-42 weeks postconceptional age for preterm infants and within 15 days of birth for term infants. Total body FM was assessed by an air displacement plethysmography system and subcutaneous abdominal and intra-abdominal AT were assessed by magnetic resonance imaging using a commercially available software program. Results: Compared to term infants, mean (SD) total body FM (g) (636.7 (247) vs. 418.4 (253), p < 0.0001) and mean (SD) subcutaneous abdominal AT (g) (123 (36) vs. 98.9 (22), p < 0.001) were significantly higher in preterm infants but mean (SD) fat-free mass (g) (2,530 (420) vs. 2,965 (389), p < 0.0001) and mean (SD) intra-abdominal AT (10.9 (5.2) vs. 18.2 (13.2), p = 0.001) were significantly lower. Conclusions: In the absence of severe illness during the hospital stay, prematurity, although associated with increased total body FM, does not appear to be associated with a relative increase in intra-abdominal AT compared to term infants.

Effect of foetal and infant growth and body composition on respiratory outcomes in preterm-born children

“…In contrast, a study of 5-7 year preterm-born children reported there was no increase in fat mass or abdominal adiposity compared to term-born children [85]. In another study, preterm-born children had increased total body fat mass at term equivalent age but not increased intra-abdominal adipose tissue when compared to term-born infants [86].…”

Body composition at birth and its relationship with neonatal anthropometric ratios: the newborn body composition study of the INTERGROWTH-21st project

“…We also demonstrated that, at birth ( Table 4 ), preterm babies have less BF% and FM and less FFM than their term counterparts. Low FM at birth is clinically important because both very small and late preterm babies accumulate FM by the time they reach “term”-corrected age, and so have higher BF% than term newborns ( 21 , 28 , 29 , 30 , 31 , 32 , 33 ). Preterm babies also have less FFM, which is relevant as reduced FFM levels remain in very preterm boys at least up to 5 years of age ( 34 ).…”

“…Furthermore, the main difference between growth-restricted and AGA newborns is in subcutaneous fat; intra-abdominal amounts are similar ( 14 ). Moreover, compared with term infants, the increase in intra-abdominal fat in healthy, preterm infants by the time they reach 40–42 weeks post-conceptual age is small ( 29 ), and preterm infants do not have a higher percentage of intra-abdominal fat by 5–7 years of age ( 35 ).…”

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

“…Modi and colleagues [17] found a positive relationship in preterm infants between the increase in intra-abdominal adipose tissue content at term, which has been associated with cardiometabolic risk factors [18], and illness severity during hospitalization. On the contrary, healthy preterm infants do not show an aberrant intra-abdominal adiposity at term [19]. …”