Abstract
Abstract:
Introduction
The mean normal birth weight established for the Polish population is slightly over 3,500 g, with reference values between 2,500 g and 4,000 g. Since birth weight appears to be one of the most important determinants of growth, both too high and too low birth weight are associated with increased risk of developmental disorders affecting growth and metabolic processes. During intrauterine life, genetic factors, food and oxygen availability, and hormonal regulatory effects play a crucial role in fetal development. The most important hormones and factors affecting fetal growth are: growth hormone (GH), insulin-like growth factor (IGF), insulin, and thyroid hormones. In adults, GH, IGF-1, and insulin markedly influence the synthesis and secretion of two appetite-regulating hormones: ghrelin and leptin. However, studies documenting their function and release during fetal life are still lacking.
Aim
The purpose of the study was to evaluate the cord blood concentration levels of GH, IGF-1, IGF-BP3, insulin, ghrelin, and leptin, and determine the relationship between the concentrations of these bioactive factors and anthropometric measurements of infants with normal, low, and high birth weight.
Material and methods
The study was conducted on 267 healthy newborns. They were divided into three study groups by weight: normal birth weight (NBW, birth weight between 2,500 g and 4,000 g, n = 65), low birth weight (LBW, birth weight below 2,500 g, n = 72), and high birth weight (HBW, birth weight over 4,000 g, n = 139). At birth, the circumference of the head, chest, abdomen, thigh, and arm were measured and body mass was recorded. In cord blood samples, the concentrations of GH, IGF-1, IGF-BP3, acyl ghrelin, leptin, and insulin were estimated using immunoenzymatic methods and RIA.
Results
As regards the tested hormones, there were statistically significant differences between the studied groups. The highest levels of acyl ghrelin and the lowest levels of leptin, insulin, and IGF-1 were recorded in the LBW newborns. Similarly, the highest levels of leptin, insulin, IGF-1, and IGF-BP3, and the lowest concentration of acyl ghrelin and GH were observed in the HBW infants. There were several correlations between the studied hormones and birth anthropometric parameters in the LBW group. Birth mass correlated positively with cord blood leptin (rs = 0.80; p< 0.01), head circumference correlated positively with acyl ghrelin level (rs = 0.82; p< 0.01), and chest circumference, with insulin (r = 0.95; p = 0,04). The abdominal circumference as well as arm circumference were negatively associated with GH concentration (rs = −0.69; p< 0,03 and rs = −0.76; p< 0,02, respectively). In the two remaining groups, HBW and NBW, no associations were observed except for a positive correlation between birth mass and leptin in the NBW newborns (r = −0.45, p<0.05).
Conclusions
Cord blood insulin, leptin, acyl ghrelin, and GH correlated with anthropometric measurements of newborns. In newborns with low-birth-weight inhibition of growth, adaptive changes concerning appetite-regulating hormones were observed. HBW newborns demonstrated increased insulin and leptin levels. Apart from typical growth factors activity (insulin, GH, IGF-1), leptin and ghrelin may play a significant role in the fetal somatic development.