A woman may bleed for up to two weeks after a miscarriage, according to About.com. Bleeding that lasts longer than two weeks may indicate an incomplete miscarriage. In an incomplete miscarriage, tissue from the pregnancy remains in the uterus, posing an infection risk.
A miscarriage is the loss of a pregnancy before 20 weeks of gestation, states WebMD. Aside from vaginal bleeding, abdominal and pelvic pain, the most common symptoms of a miscarriage are cramping and the passing of tissue from the vagina. Bleeding may be heavy or light, depending on the length of the pregnancy.
Most miscarriages happen during the first trimester, or 13 weeks, of pregnancy, according to The March of Dimes. Miscarriages affect 10 to 15 percent of all women who know that they are pregnant. This number rises to 50 percent when women who are unaware of their pregnancies are included in the statistic.
A spontaneous miscarriage usually occurs in response to a pregnancy that develops improperly, says WebMD. Doctors may not know the exact cause of a miscarriage, though they agree that it is not caused by stress, sex or exercise. A miscarriage cannot be prevented, nor can it be treated once it begins. Fever, significant blood loss and weakness in the aftermath of a miscarriage can indicate infection, and these symptoms must be addressed by a doctor.