Embodiments are directed to methods of examining preimplantation factor (PIF) binding to a subject's circulating immune cells as a marker for immune dysregulation. Some embodiments are directed to methods of detecting a level of immune dysregulation sufficient to cause recurrent pregnancy loss (RPL), methods of detecting a level of immune dysfunction sufficient to cause endometriosis, and methods of detecting a level of immune dysfunction comprising administering an effective amount of PIF or an analog thereof, and examining its binding to circulating immune cells. Within those methods, an about twenty percent change in PIF binding to a subject's circulating immune cells indicates a level of immune dysfunction.
