The flow of brown secretions in the fifth week of pregnancy is an abnormal phenomenon, which may be caused by vaginitis, the implantation of the gestational sac, and pre-miscarriage. 1. Vaginitis: After pregnancy, women’s body resistance decreases and vaginitis may occur. As the inflammation of vaginitis continues to worsen, a small amount of vaginal bleeding may occur. It is recommended that pregnant women be examined by vaginal secretions to determine which type of bacterial infection is present, and targeted treatment can be provided under the guidance of a doctor. 2. Pregnancy sacs: In the early stages of pregnancy, the pregnancy sacs may bleed, manifested as brown discharge, if there is no abdominal pain, this situation does not need to be overly nervous, a few days after the natural disappearance. 3. Pre-eclampsia: Pregnant women with symptoms of pre-eclampsia may manifest as vaginal bleeding, while there is a slight abdominal pain symptoms. It is recommended that women go to the hospital in time to check the progesterone level and HCG level, and at the same time to clarify whether the embryo is developing normally in the uterus, and once found to be in danger, to preserve the fetus as soon as possible. Women are advised to pay more attention to their health and prohibit sexual intercourse when the embryo is unstable after five weeks of pregnancy. Once pregnant women experience symptoms such as vaginal bleeding and abdominal pain, they should be diagnosed clearly and treated as soon as possible.