Two hundred Chinese primigravidae had 50 g 3-h oral glucose tolerance tests (OGTTs) twice in pregnancy; between 20 and 24 weeks and between 30 and 34 weeks of gestation. In 149 women, a single sample was taken for insulin-like growth factor-binding protein-1 (IGFBP-1) measurement 0, 1, 2 or 3 h after the glucose load at both visits; in 55 women IGFBP-1 levels were estimated in all four OGTT samples. Fetal growth was assessed by ultrasound performed at the first and second visit and, if possible, at term, and by anthropometry of the neonate. Cord serum IGFBP-1 was measured in 144 of the babies. Mothers who developed gestational diabetes were excluded.
Maternal levels of IGFBP-1 were inversely related to glucose levels at 0, 1 and 2 h in the third trimester of pregnancy. IGFBP-1 measured at 1 h in an OGTT increased between the second and third trimester. There was an inverse correlation between maternal IGFBP-1 measured in the second trimester and all fetal measurements at that time, and with most neonatal measurements and birthweight. Levels of IGFBP-1 in the third trimester were inversely correlated to neonatal abdominal circumference, skinfold thickness and birthweight. Cord blood IGFBP-1 was inversely related to growth of abdominal circumference. The strongest inverse relationship was between IGFBP-1 and maternal weight. Fasting glucose in the second trimester was positively correlated to fetal subcutaneous fat and growth of abdominal circumference. In the third trimester it was related to fetal abdominal circumference, the growth of abdominal circumference, birthweight and neonatal skinfold thickness. In a multiple regression analysis, both glucose and IGFBP-1 were shown to be determinants of birthweight. It is concluded that IGFBP-1 levels are related to glucose tolerance in pregnancy, and that both IGFBP-1 and glucose have a role in determining birthweight.
Journal of Endocrinology (1993) 136, 319–325