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.

Elevated second-trimester amniotic fluid concentration of insulin-like growth factor binding protein-1 in fetal growth retardation.

OBJECTIVE: The aim was to study the levels of amniotic fluid and maternal serum insulin-like growth factor binding protein-1 levels at 15 to 16 weeks' gestation with regard to fetal growth in the third trimester. STUDY DESIGN: Amniotic fluid (n = 148) and maternal serum (n = 129) levels of insulin-like growth factor binding protein-1 were prospectively measured. RESULTS: Elevated amniotic fluid insulin-like growth factor binding protein-1 levels were related to fetal growth retardation. At a cutoff value of 3 multiples of the median a high-risk group comprising 16% of all pregnant women was identified. This group included 40% of all small-for-gestational age (birth weight < 10th percentile) and 55% of all very-small-for-gestational-age (birth weight < 5th percentile) infants. Maternal serum insulin-like growth factor binding protein-1 levels were not significantly elevated in these groups. CONCLUSION: In most cases of intrauterine growth retardation the disturbance may exist before the condition is detectable by ultrasonography. An elevated amniotic fluid insulin-like growth factor binding protein-1 level may be an early sign.