24 to 48 hours before labour starts, capillary rupture can occur as the fetal membranes near the inner cervical opening separate from the cervical wall, resulting in a small amount of bleeding. The blood in the leucorrhoea at this time is a sign that labour is about to start, but if the amount of blood in the leucorrhoea exceeds the amount of menstruation, you should be alert to a possible pathological cause.