It is well known that serum IGF-I concentrations are regulated endocrinologically since IGF-I has a growth-promoting action as a mediator of growth hormone. However, recent reports suggest that nutritional states influence serum IGF-I concentration because IGF-I shows anabolic effects like insulin.
The aim of this study was to clarify the influences of maternal nutritional states or metabolism on the IGF-I concentrations in normal and abnormal pregnancy. In normal pregnant women, a significant positive correlation was indicated between serum IGF-I concentrations and maternal weight gain during pregnancy or serum triglyceride levels, and a significant negative correlation was observed between serum IGF-I concentrations and serum total protein levels. In the cases complicated with hyperemesis or hyperthyroidism during early gestation, a marked reduction of maternal body weight was observed, and serum IGF-I concentration was extremely low compared with that in normal pregnant women, but serum IGF-I levels gradually increased as the maternal body weight recovered after treatment by intravenous hyperalimentation or an anti-thyroid drug. In cases of severe toxemia of pregnancy, maternal weight gain and serum triglyceride levels were markedly increased, but serum IGF-I levels were significantly lower compared with those in normal pregnant women in the same gestational age. In severe toxemia of pregnancy, there was no significant correlation between serum IGF-I levels and maternal weight gain or serum triglyceride levels, and these results may be influenced by such abnormalities as water retention, hemoconcentration, severe hypoproteinemia and severe negative nitrogen balance not found in normal pregnancy.
In conclusion, it is considerated that IGF-I concentration is regulated not only by endocrinological factors, but also by metabolic factors in maternal circulation during pregnancy, and the measurement of maternal IGF-I concentration seems to be a useful parameter to evaluate the maternal nutritional states.