I have had three miscarriages. Each time though I knew that I was pregnant. Then I had major cramping, bleeding and then a loss of a mass of tissue. However my gynocologist has told me that many women have miscarriages because the embyro did not implant properly, and the only thing they experience is a much heavier period that may come late. It is not always possible. I was told that this is natures way of dealing with a pregnancy that has no chance of surviving