In early pregnancy, if there is blood in the uterine cavity, it belongs to pre-eclampsia, the common causes are as follows: 1, progesterone content is relatively low, is the main cause of pre-eclampsia uterine cavity blood, in early pregnancy is by the gestational corpus luteum secretion progesterone, so the progesterone content will exist a relatively large fluctuation range, low progesterone content is easy to appear pregnancy sac bleeding; 2, strenuous exercise, in early pregnancy after the fertilized egg is bedded, will be more sensitive to The fertilized egg is more sensitive to strenuous exercise, and it is easy to have meconium bleeding and blood accumulation in the uterine cavity; 3. The poor development of the fertilized egg is also the main cause of blood accumulation in the uterine cavity in early pregnancy, such as having fetal abortion or abnormal gestational sac, which can also be manifested as pre-miscarriage. Therefore, if blood accumulation in the uterine cavity occurs in early pregnancy, hormones should be checked and ultrasound should be done to understand the development of the fertilized egg, and only if the fertilized egg is well developed is it necessary to keep the pregnancy.