Not every newly pregnant woman has an implantation bleeding. In fact, only roughly a third of all of those who conceived will ever have one. Fertilized eggs make their way down from the fallopian tubes to the uterus, where they will try to implant into the lining of the uterus. Because this lining contains rather a lot of fleshy and bloody tissue, implantation is sometimes marked by a bit of bleeding. The most notable difference between an implantation bleeding and your period is that it normally occurs before your period is due. Most sources will tell you that it will happened any time from seven to ten days after your ovulation, but it has happened to me even sooner than that.
Whatever the case, implantation bleeding will strike before you expect your period. Menstrual flow usually starts off with a few drops of blood, and then quickly progresses to larger amounts. The spotting that you notice with implantation bleeding is different in that it will stop at a few drops, and never progress. If you notice heavy blood flow before your period is due, and especially if you have other symptoms like pain and cramping, it is wise to get in touch with your healthcare provider.
These symptoms could be connected to an early miscarriage or even a chronic health condition, like endometriosis. When a fertilized egg implants itself into the lining of your womb, the tissue that is released needs a few days to travel down and come out. By the time you notice the spotting, it is likely to be dark red or brown in color, because it is already old blood. Some women have slight cramping along with their implantation bleeding, and those who are charting to conceive might notice another shift in their basal body temperature. For most, light spotting is the only symptom though.