Changes in maternal serum insulin-like growth factor-I during pregnancy and its relationship to maternal anthropometry.

BACKGROUND Insulin-like growth factor (IGF)-I is primarily produced by the liver under the stimulation of growth hormone, and has systemic growth effects. Placental growth hormone in maternal circulation increases from early pregnancy and is responsible for the increment in maternal serum IGF-I. The purpose of this study was to evaluate the changes in maternal serum IGF-I during pregnancy and their relationship to maternal anthropometry, including body weight (BW) and body mass index (BMI). METHODS We obtained 332 blood samples from 114 expectant mothers at different gestational ages (Gas) without adverse medical history. Serum IGF-I levels were measured by immunoradiometric assay. Linear regression analysis for continuous variables and t test for comparisons of categorical variables were used to test for significance. RESULTS Maternal serum IGF-I during pregnancy was significantly correlated not only to GA (p < 0.001, r = 0.358), but also to maternal BW (p = 0.001, r = 0.202), and maternal BMI (p < 0.001, r = 0.263). The mean maternal IGF-I was highest in the third trimester [1st vs. 2nd, p < 0.001, 95% confidence interval (CI) = -70.17 to -28.22; 1st vs. 3rd, p < 0.001, 95% CI = -138.02 to -76.94; 1st vs. 3rd, p < 0.001, 95% CI = -88.86 to -27.71]. CONCLUSION Maternal serum IGF-I is significantly related to GA, maternal BW, and BMI during pregnancy.