If the volume of fluid in the uterine cavity during pregnancy is less than 1 cm and the progesterone level is normal, the fluid usually disappears in about a week. If the volume of fluid in the uterine cavity is more than 3 cm and the progesterone level is less than 20 ng/ml, the fluid may take about half a month to disappear. If a small amount of fluid appears in the uterine cavity in early pregnancy, it can be observed first if it does not affect the growth and development of the embryo, and usually the fluid can be gradually absorbed as the number of days of pregnancy increases. If there is a lot of fluid in the uterine cavity in early pregnancy and preterm miscarriage occurs, fetal preservation treatment can be given. Usually it takes about 10 days of treatment before observing the disappearance of fluid. Due to the difference in the amount of fluid in the uterine cavity and the difference in the level of progesterone, there is a big difference in the time of disappearance of fluid in the uterine cavity. If the amount of fluid in the uterine cavity is small and the progesterone level is normal, the fluid usually disappears in about a week. If the volume of fluid in the uterus is large and the progesterone level is low, the fluid may take longer to disappear. In conclusion, there is no specific treatment for uterine effusion. If there is no abdominal pain or bleeding, the pregnant woman can be observed by regular ultrasound examinations.