Insulin-like growth factor in pregnancy: studies in a growth hormone-deficient dwarf

Serum concentrations of insulin-like growth factors I and II (IGF I and IGF II) were measured before, during and after pregnancy in a GH-deficient dwarf. At no time during these periods did the patient secrete GH in response to an arginine infusion or insulin tolerance test. IGF I and IGF II concentrations before pregnancy were low and similar to those of patients deficient only in GH. During the 35th week of gestation, IGF I and IGF II serum concentrations were within the normal range (165 and 127 ng/ml for IGF I and 740 and 860 ng/ml for IGF II). Abnormally low values of IGF I and IGF II were again recorded 36 h postpartum and 35 days later. These data indicate that some material, probably of placental origin, stimulates the secretion of not only IGF I, but IGF II as well. Alternatively, the human placenta may produce IGF. Such secretion can occur without the prior maternal secretion of pituitary GH.