Cord serum insulin-like growth factor binding protein-1 and -3: effect of maternal diabetes and relationships to fetal growth

OBJECTIVES: Insulin-like growth factor binding protein-1 and -3 (IGFBP-1 and -3) are the main insulin-like growth factor (IGF) carriers in fetal blood whose concentrations are regulated by hormonal factors such as insulin. IGFBPs may regulate fetal growth by altering the biological activity of IGF-I and IGF-II. We studied the effect of maternal diabetes on cord serum IGFBP-1 and IGFBP-3 levels, and the usability of IGFBP-1 and IGFBP-3 in the detection of birth weight variations. METHODS: Cord serum IGFBP-1 and IGFBP-3 concentrations were measured at birth by immunofluorometric assays in 67 pregnancies with type 1 diabetes and in 62 normal pregnancies. RESULTS: Concentrations of IGFBP-1 in cord serum were lower in diabetic pregnancies than in normal pregnancies (156 +/- 28 microg/l vs 266 +/- 29 microg/l, P = 0.007), whereas those of IGFBP-3 did not differ significantly (3327 +/- 158 microg/l vs 2982 +/- 105 microg/l, P = 0.076). IGFBP-1 correlated negatively and IGFBP-3 positively with birth weight z-score in diabetic pregnancies. The trend was similar in normal pregnancies. In multiple regression models, birth weight z-score was significantly associated with IGFBP-1 in diabetic and normal pregnancies, and with IGFBP-3 in diabetic pregnancies.CONCLUSION: Maternal diabetes is associated with suppressed levels of IGFBP-1 in cord serum, whereas those of IGFBP-3 do not change markedly. In diabetic pregnancies, both cord serum IGFBP-1 and IGFBP-3 correlate with fetal growth.