Premature progesterone elevation in controlled ovarian stimulation: to make a long story short.

Over the past decades many of us have contributed to the controversy surrounding the origins and consequences of premature progesterone elevation during controlled ovarian stimulation. In this article, we attempt to retrace the progression of information on this complex subject which required reviewing a number of publications that often contradicted one another. The definition of premature progesterone elevation, the pathophysiological mechanisms underlying the high peripheral progesterone levels, and the debated consequences of this event on in vitro fertilixation-embryo transfer outcome will be addressed from a historical perspective.