This project will define the basic endocrinology of anti-Müllerian hormone (AMH), to understand its function and to rapidly improve its clinical use as a biomarker of ovarian function. We have discovered that the ovary releases two forms of AMH; an inactive precursor (proAMH) and a receptor-binding form (AMHN,C). proAMH may be a long-term basal regulator whereas AMHN,C may be an acute regulator that varies depending on the state of the ovary. We have invented AMH species-specific ELISAs, and we will determine what form of AMH varies during menstrual cycling and pregnancy.We will also determine whether proAMH in blood is converted to AMHN,C using mice. The AMH released by the ovary may control miscarriage during pregnancy.We will test this hypothesis by comparing and contrasting pregnancies in mice with altered AMH expression. The project outcomes may improve the assessment of subfertility in women and yield therapeutic developments related to recurrent miscarriage.