Percentile-Based Reference Values of Umbilical Cord Blood Insulin-like Growth Factor 1 in Japanese Newborns

Abstract

We aimed to create percentile-based reference values of the umbilical cord blood insulin-like growth factor-1 (IGF-1) levels in Japanese newborns, as these values have not yet been established. A total of 259 newborns were classified into four gestational-age-at-birth (GA) groups: extremely preterm (<28 weeks); early preterm (28–33 weeks); late preterm (34–36 weeks); and term (≥37 weeks). They were further subclassified as small-for-gestational-age (SGA) or non-SGA. The 10th, 25th, 50th, 75th, and 90th percentiles of the umbilical cord blood IGF-1 levels were calculated and compared between the groups by using reference values of 9, 18, 33, 52, and 71 ng/mL, respectively. In the extremely preterm group, the IGF-1 levels were significantly lower than those in the early preterm, late preterm, and term groups (13.5, 24.0, 44.5, and 47.5 ng/mL, respectively; p < 0.001). The umbilical cord blood IGF-1 levels in the SGA newborns were significantly lower than those in the non-SGA newborns in all subgroups. In multivariate analyses, the GA and birth weight standard deviation scores were independent determinant factors for the umbilical cord blood IGF-1 levels. Thus, we established percentile-based reference values of umbilical cord blood IGF-1 in Japanese newborns; these reference values can be applied on the basis of the extent of prematurity and the SGA status.

Adverse Skeletal Muscle Adaptations in Individuals Born Preterm—A Comprehensive Review

“…Similar to PB-induced effects on the heart, there are also known adverse impacts on skeletal muscle. Individuals born preterm show blunted insulin sensitivity [26], low circulating vitamin D [27] and insulin-like growth factor-1 (IGF-1) concentrations [28], and a relatively higher proportion of type II muscle fibers [29] than control counterparts. Further, other findings show that prematurity is associated with higher levels of oxidative stress [30], potential epigenetic changes [31], and potential alterations to skeletal muscle amino acid uptake [17].…”