The presence of brown blood may be due to a biochemical pregnancy or due to a preterm miscarriage, depending on the circumstances. Biochemical pregnancy, or subclinical pregnancy, is usually a phenomenon in which the fertilized egg fails to return to the uterus after sperm-egg union, or returns to the uterus but fails to settle, and may flow out of the body with menstruation, showing symptoms of brown blood. When patients undergo ultrasound examination, the presence of a gestational sac in the uterus is usually not detected. Occasional biochemical pregnancy will not affect the body much and there is no need to worry too much. If it occurs repeatedly, it is necessary to go to the obstetrics and gynecology department for further examination. If a biochemical pregnancy is diagnosed, patients are advised to adjust their work and rest and follow the doctor’s recommendations for medication and other related treatments to effectively regulate the body and prevent biochemical pregnancy. In case of brown blood, regular monitoring of blood HCG is needed to clarify its growth and determine whether the gestational sac is viable or has been expelled from the body. In addition, if the ultrasound examination shows that your body is in good condition, you can prepare for pregnancy again after every other month or three months.