Whether a small amount of brown discharge in the second trimester of pregnancy is serious needs to be judged according to the cause, if it is bleeding on implantation is usually not serious, if it is a pre-eclampsia or ectopic pregnancy, it is more serious. 1. Bleeding on implantation: After pregnancy, under normal circumstances, a woman’s endometrium will be thicker than usual, and there will be a small amount of bleeding when the blood vessels of the endometrium rupture after the embryo is implanted. This is a physiological manifestation which is generally not serious and does not require special treatment. 2. Pre-eclampsia: It is an early pregnancy manifestation, easy to appear in the first trimester of pregnancy, which may be related to the abnormal development of the embryo itself, or it may be caused by the exposure of the pregnant woman to the environment and food that will harm the development of the embryo. Need to follow the doctor’s advice as soon as possible to preserve the fetus treatment. 3. Ectopic pregnancy: it is a kind of ectopic pregnancy, mainly refers to the embryo is not in the uterus, but in the place outside the uterus, if not treated in time, it will bleed frequently, and in serious cases, it will bleed profusely, and need to be treated with surgery as soon as possible. A small amount of brown discharge in the second trimester of pregnancy requires prompt medical attention and relevant examinations according to the doctor’s advice to analyze the cause and then treat the symptoms to avoid increased bleeding.