Bone Abstracts

Backgound: Limited data are available on body composition of preterm compared to born at term infants. The aim of our study was to compare bone mass, fat mass-FM and free fat mass-FFM in preterm and term infants at 40^th weeks of gestational age (GA).

Methods: Thirty-four preterm infants (14M, 20F) born at 31.0±2.2 weeks of GA (range 26–36+3 weeks) and n=8 term neonates (4M, 4F) born at 39.7±1.0 weeks of GA underwent a total body DXA scan less head (TBLH, LUNAR Prodigy, Infant software) at 40.9±1.8 weeks of GA. Bone mineral content (BMC, g), bone mineral density (BMD, gr/cm²), FM (gr and %) and FFM (gr) were obtained at the TBLH and at the trunk (based on an automatic designed ROI).

Results: Preterm were lighter than born at term infants (1597.2±534.7 vs 3465±260.1 gr, P<0.0001) and shorter (42.4±5.1 vs 50.7±1.7 cm, P=0.0002) at the time of birth, but comparable for weight and length at the time of evaluation; they displayed more FM (19.4±5.1% vs 16.7±6.3%, P=0.19) and similar FFM. Moreover, preterm infants had a lower BMD (0.207±0.048 vs 0.275±0.011 gr/cm², P=0.0004), BMC (25.6±6.3 vs 48.2±6.8 gr, P<0.0001) and area (126.6±28.5 vs 175.0±20.1 cm², P<0.0001) at the TBLH and lower BMD (0.195±0.046 vs 0.252±0.020, P=0.0016), BMC (13.5±4.1 vs 26.1±4.4, P<0.0001) and area (71.0±18.4 vs 103.4±12.9, P<0.0001) at the spine compared to born at term neonates. All bone parameters were related to birth weight (r’s range=0.13–0.52, all P’s<0.05) and GA (r’s range=0.17–0.37, all P’s<0.05) in preterm infants. However, multiple regression analysis showed that in preterm FFM was a positive (β 4.736e-5, P=0.0305) and %FM an negative predictor (β −0.003, P=0.0078) of TBLH BMD (adj.R²=0.646, P<0.0001), after adjustment for GA and birth weight.

Conclusions: Our preliminary data demonstrate that preterm infants exhibit early recovery in weight and length, but deficient gain in bone mass at the TB and the spine compared to born at term infants; interestingly, already at the age of ‘correspondent 40 weeks of GA’ FFM seems to be more important than birth weight or prematurity for bone mass development, while fat mass might have a negative impact.

Disclosure: The authors declared no competing interests.