Regulation of maternal insulin-like growth factor I by placental growth hormone in pregnancy. Possible action of maternal IGF-I on fetal growth.

In normal and in pathological human pregnancies, a specific placental growth hormone variant, rather than placental lactogen, substitutes for the suppressed pituitary GH to stimulate the maternal insulin-like growth factor I (IGF-I). In pathological pregnancies with disorders of the feto-placental unit, low levels of placental GH hormone result in relatively low levels of maternal IGF-I. In normal pregnancies, the baby birth weight is positively correlated with maternal IGF-I values.