Once a pregnant woman develops blood accumulation in the uterine cavity, if the amount of accumulated blood is relatively small, it may not have a big effect; however, if the amount of accumulated blood is relatively large, it may affect the baby. 1. Small amount of blood accumulated in the uterine cavity: If the amount of blood accumulated in the uterine cavity is relatively small, the blood accumulated in the uterine cavity will be gradually absorbed with the passage of time, which generally does not have much effect on the fetus. 2. Large amount of blood accumulated in the uterine cavity: However, if the amount of blood accumulated in the uterine cavity is relatively large, then it will not be completely absorbed by the uterus, and this blood can occupy a certain amount of space in the uterus, which will lead to obstruction of the space for the fetus to move around, and pressure on the limbs, and may also trigger contractions, leading to miscarriage, and so on. It is recommended that once a pregnant woman discovers that she has blood in the uterus, she should consult a doctor in time to improve other relevant examinations and standardize the treatment.