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A. Bleeding in early pregnancy is very common and is generally no cause for concern. Around half of all pregnant women have a little bleeding in the early months of pregnancy. Although some of these women may later suffer a miscarriage, the majority carry on to have normal and straightforward pregnancies. SOME WOMEN BLEED FOR A FEW DAYS around the time of their expected periods, especially during the first trimester of pregnancy. This bleeding is usually much lighter than a normal period, but may be accompanied by discomfort - sometimes even pain - and a heavy, dragging feeling. The medical term for this sort of bleeding is 'decidual' bleeding. The 'decidua' is the innermost lining of the uterus, the part lost during each menstrual period. Experts think that this bleeding is from that part of the decidua that is not yet covered by the developing embryo and placenta. Very early bleeding may be 'implantation' bleeding rather than decidual bleeding. Implantation bleeding happens about two weeks after conception, when the fertilised egg reaches the uterus and embeds in the soft lining. Special cells surrounding the egg burrow deep into the lining, almost like a seed putting out tiny roots. This is the start of the placenta. Some women loose a little blood when this takes place. Implantation bleeding rarely lasts for more than a day.