Maternal and Fetal IGF-I and IGF-II Levels, Fetal Growth, and Gestational Diabetes

Context: It remains uncertain whether maternal IGF-I is associated with fetal growth. Little is known about the role of maternal IGF-II in fetal growth and whether IGF-I or IGF-II is implicated in fetal hypertrophy in gestational diabetes. Objective: The objective of the study was to assess maternal and fetal IGF-I and IGF-II levels in association with fetal growth and gestational diabetes. Study Design, Population, and Outcomes: A singleton pregnancy cohort study (n = 307). The primary outcome was birth weight. Results: Maternal plasma concentrations increased by an average of 55.4% for IGF-I and 11.8% for IGF-II between 24-28 and 32-35 weeks of gestation. The maternal IGF-I but not IGF-II level was correlated with birth weight and placental weight. Adjusting for maternal and infant characteristics, each SD increase in maternal IGF-I level at 24-28 weeks was associated with a 75-g (95% confidence intervals 29-120) increase in birth weight, a 20-g (7-33) increase in placental weight, and a 1.91-fold (1.28-2.86) higher odds of macrosomia (birth weight >90th percentile). Similar associations were observed for the maternal IGF-I level at 32-35 weeks. Maternal and fetal IGF-I (but not IGF-II) levels were significantly higher in gestational diabetic than in nondiabetic pregnancies. The significantly higher birth weight z scores in diabetic pregnancies disappeared after adjusting for maternal and fetal IGF-I levels alone. Conclusions: Higher maternal IGF-I (but not IGF-II) levels at mid-and late gestation may indicate greater placental and fetal growth. IGF-I (but not IGF-II) may be implicated in fetal hypertrophy in gestational diabetes. (J Clin Endocrinol Metab 97: 1720-1728, 2012)