We are seeking participants for a study of menstruating individuals with and without heavy menstrual bleeding.  The purpose of this study is to understand the role of different clotting factors in controlling uterine bleeding and the role of a certain cell type (endometrial endothelial cells) in regulating those clotting factors. 

Participants will attend one enrollment visit, scheduled at their convenience.  At that visit each participant will be given a menstrual cup and a form on which to indicate how many pads/tampons they use each day.  Participants will have a second visit on the first day of their next period, where they will have a blood draw and will drop off a sample of menstrual blood, collected in the provided menstrual cup.  They will then return to drop off a sample of menstrual blood each day of that period.  The final visit will occur about 3 weeks after the first day of that same period, at which a sample of the uterine lining will be obtained using a very small, plastic tube.  At that visit each participant will be asked to return the form on which they noted how many pads or tampons they used during that period.