The growth hormone and insulin-like growth factor 1 (GH/IGF1) axis is a key regulator of postnatal mammalian growth. Humans produce two growth hormone proteins, GH-N and a placental variant GH-V. GH-N is secreted in a pulsatile fashion from the pituitary, and regulates IGF1 release from the liver, while the placental variant of GH is secreted tonically from the placenta during pregnancy. In pregnancy, concentrations of GH-N in the maternal serum decline, while GH-V increases in the circulation from week five, gradually replacing maternally derived GH-N completely. Although the exact role of GH-V is still unclear, this remarkable change in spatial and temporal GH secretion patterns is proposed to play a role in mediating maternal adaptations to pregnancy. GH-V is pro-angiogenic and increases maternal levels of other important growth factors, such as IGF1. It may also enhance nutrient transfer across the placenta.
GH-V is associated with fetal growth, and its circulating concentrations have been investigated across a range of pregnancy complications. Altered maternal serum levels of GH-V have been observed in certain pregnancy complications such as fetal growth restriction and gestational diabetes mellitus. However, progress in this area has been hindered by a lack of readily accessible and reliable assays for measurement of GH-V. This talk will discuss what is known about the role of placental growth hormone and IGF1 in placental function and will describe our recent studies investigating their association with human pregnancy pathologies.