Background: Fibroblast growth factor 21 (FGF21) is a metabolic and growth regulator. Aim: To investigate the role of FGF21 during growth in infancy. Methods: Blood samples for FGF21, leptin, insulin and glucose were collected from cord blood obtained from 95 preterm and term newborns (cross-sectional group), and at 6 and 12 months of life in 80 preterm and term infants (longitudinal group). Length and weight were measured at birth, 6 months, and 12 months. Results: From birth through 12 months of age, preterm infants' linear growth and weight gain were larger than those of term infants, irrespective of birth weight SDS. At birth and at 12 months, there was no difference in FGF21 levels between preterm and term infants; in contrast, at 6 months, serum FGF21 in term infants was significantly higher than that of preterm ones. In the 0-6-month period, in the whole longitudinal group, serum FGF21 was inversely correlated to the length change SDS, and such a significant inverse correlation persisted in the preterm-AGA group in the 6-12-month period. In addition, term infants who experienced length catch-up in the first 6 months of life exhibited lower serum FGF21 levels at 6 months, and those with length catch-up growth between 6 and 12 months had a greater decrease of serum FGF21 level in the same time period. Conclusions: Our results indicate that FGF21 in infancy is inversely correlated with linear growth rate, thus suggesting that FGF21 is a negative regulator of human growth.

Rapid early growth is associated with adverse metabolic outcome. The aim of this study was to determine whether there are differences in body composition (BC) between very-low-birth-weight preterm (VLBWPT) infants born appropriate for gestational age (AGA) and small for gestational age (SGA) and whether these differences relate to first-year growth. Twenty-six VLBWPT (15 AGA and 11 SGA). The BC was analyzed by dual X-ray absorptiometry at 2 years, and insulin-like growth factors (IGFs) I and II and leptin were administered weekly for 8 weeks and at 1, 3, 6, and 12 months. At 24 months, the VLBW SGA infants were lighter and had less peripheral fat and lean mass than VLBW AGA infants. In all patients, the percentage of fat mass correlated inversely with the change in weight [standard deviation scores (SDS)] from newborn to 2 and 4 weeks and the 1-month leptin and lean mass (SDS) correlated inversely with the change in weight (SDS) from newborn to 2, 4, and 8 weeks and with 4-week IGF-I and 8-week IGF-II. Lean mass (SDS) inversely correlated with 6-month IGF-I and directly correlated with 1-week and 3-month IGF-I in SGA VLBW infants only. A longer follow-up period will show whether additional differences will develop later.

Background: Very low birth weight (VLBW) children have higher risk of neurologic disabilities and growth factors are essential for brain maturation. Aim: To assess whether there are differences in neurologic findings, psychometric parameters and microstructural brain morphology in 1-year-old VLBW infants versus term healthy controls and whether these differences are related to hormonal/growth changes. Methods: Prospective anthropometry, prefeed venous blood sample [insulin, insulin-like growth factor-I (IGF-I), insulin-like growth factor-II (IGF-II), leptin, glucose], neurologic and imaging assessment, at age 1 year in 34 VLBW infants (12 SGA; 10 M) and 10 healthy term controls (5 M). Results: IGF-I concentrations at 1 month of corrected age were 20% lower in SGA versus appropriate for gestational age VLBW (p < 0.02). Gray and white matter volume and fractional anisotropy in 15/27 regions were decreased (p < 0.001). Abnormal spectroscopy was observed in 4 zones in VLBW versus term controls (p < 0.001). Some of these changes were associated with different periods of first-year growth and IGF-I/IGF-II, leptin and HOMA-IR. Conclusions: VLBW infants show differences in brain volumes and microstructural brain morphology as compared to term controls, changes related to circulating growth factor and anthropometry changes in the first year. This apparent reorganization of the developing brain offers a unique opportunity to investigate the relationship between changes in cortical anatomy, cognitive and social impairments and periods of early growth.

Background/Aims: An increased preterm birth survival rate is associated with long-term neurological and metabolic risks; thus, our aim was to evaluate whether early patterns of infancy anthropometry and metabolic hormonal profile differ in preterm infants born small for gestational age (SGA) or appropriate for gestational age (AGA) from birth to 36 months of corrected age (CA). Methods: We recruited 110 very-low-birth-weight (VLBW) preterm infants (AGA = 60 and SGA = 50) with a mean birth weight of –2.39 ± 0.77 versus 0.57 ± 0.54 standard deviation scores (SDS) (p < 0.01) and birth length of –2.1 ± 1.05 versus –0.44 ± 0.82 SDS (p < 0.01), respectively. Anthropometry and blood sampling for insulin, insulin-like growth factor (IGF)-II, IGF-I, and leptin were performed for up to 3 years. Results: All neonates increased their weight, length, and head circumference SDS during the early inpatient period. Up to 90% reached a normal length within this period. The IGF-II, insulin, and glycemia concentrations changed in parallel with weight. In the first year of CA, only SGA infants gained weight and height SDS. The homoeostatic model assessment had a trend toward higher values in SGA infants at 24 and 36 months (p = 0.06 and p = 0.07). Conclusion: Being SGA is the strongest predictor of early recovery of height in VLBW preterm infants. Follow-up will allow us to determine whether the differences in the growth patterns of VLBW preterm infants by birth weight SDS persist.

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