Slight bleeding on the 40th day of pregnancy may be due to preeclampsia, ectopic pregnancy, vaginitis, and so on. It can be treated by using medicines and terminating the pregnancy. 1. Pre-eclampsia: If the pregnant woman is accompanied by abdominal pain, back pain and other symptoms, it may be caused by pre-eclampsia. At this time, pregnant women can follow the doctor’s instructions to use progesterone soft capsules, dydrogesterone tablets, etc. for treatment. If the symptoms are more serious and miscarriage is inevitable, the pregnancy can be terminated in time. 2. Ectopic pregnancy: it is the embryo is in the uterine cavity outside the place of the bed, can be determined by the blood Hcg and ultrasound examination, mostly accompanied by abdominal pain, once diagnosed, must be timely medical treatment, according to the situation to choose a conservative treatment or surgical treatment. 3. Vaginitis: Due to the changes in hormone levels in pregnant women during pregnancy, they are prone to vaginitis. Pregnant women also often experience symptoms such as vulvar itching and abnormal vaginal discharge. At this time, the cause of the disease should be clarified, if the bacterial infection, you can follow the doctor’s instructions to use drugs for treatment. If a pregnant woman has a little bit of blood on the 40th day of pregnancy, it is recommended to consult a doctor in time to complete the relevant examinations under the guidance of the doctor, to clarify the cause of the disease, symptomatic treatment.