Brown discharge in 13 weeks of pregnancy may be a premonitory miscarriage, cervical polyps, the normal phenomenon of embryo implantation, etc., and you should consult a doctor in time to find out the cause of the disease. 1. Pre-eclampsia: In addition to the cessation of embryonic development, some women are found to have intrauterine pregnancy through ultrasound, at which time the possibility of pre-eclampsia is relatively high. 2. Cervical polyps: after pregnancy, most women develop cervical polyps under the influence of hormone levels, which can easily lead to bleeding. 3. Normal phenomenon of embryo implantation: it may be due to a little rupture of the endometrium caused by embryo implantation, resulting in a small amount of bleeding gathering in the vagina or uterine cavity, which slowly turns into a brown discharge. If there is brown discharge, the first close observation; two days later there is such a phenomenon, should be timely to the regular hospital, under the guidance of the doctor’s medication to carry out fertility preservation treatment.