The cause of blood clots in the uterine cavity of pregnancy is due to a history of chronic cervicitis or a history of miscarriage, resulting in bruises in the uterine cavity for a long time without discharge. Intrauterine blood clots are not after pregnancy, but before pregnancy, after pregnancy viewed already dry blood clots, just in the usual absence of any clinical symptoms, and did not often do a physical examination, so do not know. After pregnancy due to the increase in the level of progesterone in the body, it will make the blood clots more obvious, in pregnancy to do abdominal ultrasound can be found. The cause of blood clots in the uterine cavity of pregnancy is also seen in the early stages of pregnancy, not reasonable rest or cold caused. As it is not possible to do any treatment during pregnancy, dynamic observation of the baby’s development at any time, pay attention to rest, do not strain, do not bear weight, etc., to prevent the clot rupture caused by vaginal bleeding, and so on the birth of the uterus after the operation can be treated through the operation of the uterine cavity.