Insulin and fetal growth.

This review has examined the evidence from both clinical and experimental data that insulin has a key role in stimulating fetal growth. Human disorders where excessive insulin secretion and beta cell hyperplasia are present result in fetal overgrowth. Experimental models confirm an important anabolic effect of insulin in utero. Contrasted with this data is the evidence of intrauterine growth retardation occurring in association with insulinopenia or total absence of fetal insulin. Without the anabolic effect of insulin, no amount of substrate will induce optimal growth. It is evident from both the clinical and experimental data that sensitivity to insulin (probably individual receptor sites) develops in the latter stages of pregnancy. This point of sensitivity to the anabolic action of insulin has yet to be identified in a number of fetal tissues.