Earliest time to detect hPL (Human Placental Lactogen) in maternal serum?

Human Placental Lactogen HPL is secreted by syncytiotrophoblast of placenta and is detectable in maternal serum as early as the third week after feilization. It is demonstrable in cytotrophoblast before 6 weeks. This however increases exponentially around 24 weeks and is responsible for the insulinase action and the predisposition to GDM around that time, and hence the screening protocol of OGTT (Oral glucose tolerance test) at that time. Induces maternal lipolysis Has angiogenic propeies, therefore is responsible for development of fetal vasculature.