Longitudinal changes of insulin-like growth factors and their binding proteins throughout normal pregnancy

• Published in: Annals of clinical biochemistry 2004-05, Vol.41 (3), p.220-226
• Main Authors: Monaghan, John M, Godber, Ian M, Lawson, Nigel, Kaur, Malveen, Wark, Gwen, Teale, Derrick, Hosking, David J
• Format: Article
• Language: English
• Subjects: Biomarkers - blood; Birth Weight; Enzyme-Linked Immunosorbent Assay; Female; Gestational Age; Hemodilution; Humans; Infant, Newborn; Insulin-Like Growth Factor Binding Protein 1 - blood; Insulin-Like Growth Factor Binding Protein 2 - blood; Insulin-Like Growth Factor Binding Protein 3 - blood; Longitudinal Studies; Luminescent Measurements; Male; Pregnancy - blood; Radioimmunoassay; Somatomedins - analysis; Somatomedins - metabolism; Statistics as Topic
• ISSN: 0004-5632; 1758-1001
• DOI: 10.1258/000456304323019596

Background: Insulin-like growth factors (IGFs) are anabolic proteins that are essential regulators of cell division, differentiation and growth. We describe the longitudinal changes in IGF-I, IGF-II and the binding proteins IGFBP-1, -2 and -3 before and during normal pregnancy. Method: Serum samples were taken before conception and then at 12, 24 and 36 weeks of gestation in 41 healthy women with uncomplicated pregnancies. We measured IGF-I using an automated chemiluminescent method, IGF-II and IGFBP-2 using in-house radioimmunoassays (RIAs), and IGFBP-1 and IGFBP-3 using commercial enzyme-linked immunosorbent assay (ELISA) and RIA kits, respectively. Because of the potential haemodilution effects during pregnancy, albumin was also measured in all samples. Results: There was a significant fall in IGF-I during the first (36%) and second trimesters (21%) followed by an increase of 25% at 36 weeks. During pregnancy, the mean IGF-II concentrations fell by 12% at 12 weeks, 8% at 24 and 8% at 36 weeks compared with pre-conception values. When IGF-II results were adjusted for the haemodilution of pregnancy, its concentrations increased. During pregnancy, there was a rapid increase in mean IGFBP-1 levels by 17-fold (12 weeks), 24-fold (24 weeks) and 25-fold (36 weeks). IGFBP-2 concentrations fell after conception but started to increase towards term. This increase was more significant when adjusted for haemodilution. In contrast, IGFBP-3 concentrations increased significantly throughout pregnancy. Conclusion: Our data on the physiological changes of IGFs and their binding proteins add further evidence of the vital roles of these hormones throughout normal pregnancy.