109 Early Postnatal Growth and Insulin-Like Growth Factors in Preterm Infants

Abstract

Background: Growth is one of the most important indicators of health in infants and older children. The IGF system is one of the principal regulators of fetal growth. The third trimester is the time of life during which growth velocity is the most rapid. Little is known about how preterm birth may affect longitudinal growth, and about the relationship of the IGF system to post-natal growth. Aim: To prospectively characterise longitudinal growth and the influence on growth of IGF-I, IGF-II and IGFBP-3 in preterm infants with GA <32 weeks up to an age corresponding to 40 weeks postmenstrual age (PMA). Methods: Weekly serum IGF-I, IGF-II and IGFBP-3 concentrations were measured in 73 preterm infants from birth (PMA 23 to 32 weeks) until 40 weeks PMA or discharge from hospital. Weight, length, head circumference and lower leg length were recorded weekly. Results: 27% of the infants were born SGA and remained small during the study period. At 40 weeks PMA approximately 50 % were below -2 SDS in weight and length, indicating that extra-uterine growth restriction is present. The head circumference also showed an initial growth restriction followed by a rapid catch up growth, resulting in normal head circumference at 40 weeks PMA. Beside BW and GA, IGF-I correlated with weight, length and head circumference. Size at birth and gestational age had a significant influence on size attained later. Adjusting for these variables, IGF-I contributed significantly to explain size. Conclusion: Severe extrauterine growth restriction was found in a group of very preterm infants followed prospectively. Head circumference showed normalisation at 40 weeks postmenstrual age in contrast to weight and especially length in the most immature infants. IGF-1 but not IGF-2 or IGFBP-3 was found to have explanatory value in regression models.