Presented at the Neonatal Society 2014 Spring Meeting.
Gale C, Jeffries S, Parkinson JRC, Santhakumaran S, Durighel G, Logan KM, Uthaya S, Thomas EL, Bell JD, Modi N
Imperial College London
Background: Rapid early growth is associated with later cardiometabolic disease. Although the strongest relationship is seen in infants born small, this association is found across the birth weight range. The early infant period appears key: rapid growth in the first 3-6 months is correlated with later metabolic risk, while rapid growth after 6 months is not (1). Infancy is an important period for adipose tissue development and adiposity is recognised as a mediator of later cardiometabolic health, however there is a paucity of data describing the relationship between early growth and directly measured adiposity. We aimed to examine the association between early infancy weight gain and directly measured adipose tissue distribution and hepatic lipid, testing the null hypothesis that weight gain is not associated with altered adipose tissue distribution or intrahepatocellular lipid (IHCL) at 2-3 months.
Methods: Research Ethics Committee and NHS approvals were obtained. With informed parental consent, healthy, term, appropriate weight for gestational age (AGA) infants underwent whole body magnetic resonance imaging and hepatic spectroscopy to assess body composition and IHCL content. Investigations were performed in natural sleep on two occasions, shortly after birth, and between two and three months in accordance with our previously published protocols (2,3). Anthropometric measurements were obtained at both visits and conditional weight gain was calculated (4) as weight gain standard deviation score (SDS). Total adipose tissue volume was calculated as previously described (2). We used multivariable regression to examine total and regional adipose tissue volumes and IHCL at 2-3 months in relation to weight gain SDS, adjusting for birth weight SDS and sex.
Results: Sixty-nine infants (39 male), mean (SD) birthweight 3.402 kg (0.400), gestational age 40+0 (1+2) and maternal BMI 23.5 (3.9), underwent longitudinal scans at a median [interquartile range] age of 13 [7-19] days at T1 and 63 [56-70] days at T2. No significant correlation was detected between birth weight and weight-gain between birth and 2-3 months. After adjustment a significant positive association was detected between weight gain and all individual adipose tissue compartments (p<0.01 for all depots). A significant negative association was found between weight gain and the adipose tissue ratio internal abdominal:subcutaneous abdominal (β= -0.013 [SE 0.006], r2=0.22, p=0.03). There was no detectable association between weight gain and IHCL (β=0.22 [SE 0.34], r2=0.03, p=0.52).
Conclusion: In this cohort rapid weight gain is associated with a distribution of adipose tissue considered more beneficial in later life; this finding is unexpected and runs counter to previous reports in which indirect techniques have been applied to measure adipose tissue distribution (1). The association between more rapid weight gain and greater adipose tissue volume at 2-3 months is less unexpected; it is predictable that larger increases in body weight would be associated with larger increases in adipose tissue. Although these results require corroboration in larger studies, this population of AGA babies argues against the hypothesis that rapid early weight gain leads to detrimental alterations in infant adipose tissue partitioning which subsequently track into adulthood mediating later metabolic risk.
Corresponding author: christopher.gale@imperial.ac.uk
References
1. Chomtho S, et al Infant growth and later body composition evidence from the 4-component model. AJCN 2008
2. Modi N, et al. The influence of maternal BMI on infant adiposity and hepatic lipid content. Pediatr Res. 2011
3. Uthaya S, et al. Adipose tissue magnetic resonance imaging in the newborn. Horm Res. 2004
4. Cole TJ. Conditional reference charts to assess weight gain in British infants. Arch Dis Child, 1995