Luteal Out of Phase Event (LOOP)

This is a newly discovered peculiar change of hormonal patterns within usually a normal-length menstrual cycle in perimenopausal women. It means that in the middle of the luteal phase when progesterone and estrogen should still be high-normal, there is a second midcycle estrogen peak that often ends up around the same time as the start of the next menstrual flow. High estrogen at the time of flow is one thing associated with very heavy bleeding in perimenopause.