Background: We analyzed the role that nutrition and the insulin-like growth factors IGF-I and IGFBP-3 play on neonatal growth.
Methods: Full-term and preterm infants with 1 and 3 weeks of postnatal life (n = 54 and n = 33, respectively) were studied. Anthropmetric variables, daily intake of energy and nutrients, and serum levels of IGF-I and IGFBP-3 were measured.
Results: At the first week after birth, preterm infants had lower IGF-I levels than did those in the control group. At the third week of postnatal life, serum IGF-I and IGFBP-3 levels showed a significant increase. Preterm infants born before 33 gestational weeks showed lower IGF-I (p < 0.02) and IGFBP-3 (p < 0.02) levels than those born between 33 and 37 gestational weeks. Preterm infants fed with human milk supplemented with a formula showed higher serum IGF-I levels than those fed exclusively with a milk formula (mean ± SEM 48.2 ± 9.5 μg/L vs. 25.4 ± 4.4 μg/L, p < 0.05). IGF-I and IGFBP-3 were correlated between themselves and with energy and protein intake. Multiple regression analysis confirmed that energy intake and serum IGFBP-3 levels were the most predictable variables with regard to IGF-I levels at neonatal period.
Conclusions: These feedings suggest that IGF-I levels during the neonatal periods are influenced by the maturity stage of the newborn, energy intake, and the type of lactation.
University of La Laguna, Hospital Universitario de Canarias, Department of Pediatrics, Tenerife, Canary Islands, Spain
Received January 23, 1996; revised June 26, 1996; accepted June 26, 1996.
Address correspondence and reprint requests to M. Díaz-Gómez at Facultad de Medicina (3a fase) y Escuela Universitaria de Enfermeria y Fisioterapia, Universidad de La Laguna, Campus de Ofra, 38071 La Laguna, Tenerife, Canary Islands, Spain.