Bleeding on day 45 of pregnancy can be seen in cases of pre-eclampsia, ectopic pregnancy, pregnancy combined with cervical erosion and external irritation. If a pregnant woman has been seen in the hospital in the past and has a clear diagnosis of intrauterine pregnancy (the embryo is located in the uterus), irregular small amount of brown blood from the vagina on the 45th day of pregnancy without abdominal pain or vague abdominal pain, there is a possibility of preterm abortion, and she needs to seek medical attention promptly. If there is no abnormality in the gynecological examination of the cervix, bleeding from cervical erosion can be ruled out and pre-eclampsia is considered. If there are no obvious external factors (external impact on the abdomen, intercourse, etc.), it is mostly considered that the bleeding is caused by insufficient hormone level (HCG or progesterone) in the body to maintain the nutritional demand of the embryo development on the endometrium, which leads to bleeding. In this case, the blood HCG and progesterone levels should be rechecked and the early pregnancy ultrasound should be repeated. If the ultrasound indicates normal embryo development, but the trend of blood hormone level growth is unsatisfactory, the pregnant woman should rest in bed and take oral fetus preservation drugs, if there is no relief, breech intramuscular injection of progesterone type drugs for fetus preservation treatment; if the ultrasound indicates embryo abortion and the blood hormone level decreases significantly compared with before, the patient is considered to have unavoidable miscarriage and needs to undergo uterine evacuation as soon as possible. If the pregnant woman has no clear intrauterine early pregnancy in the past, only positive urine test paper at home, bleeding on the 45th day of pregnancy does not exclude the possibility of ectopic pregnancy, she should go to the hospital in time for a clear diagnosis, and if accompanied by obvious abdominal pain symptoms, she should immediately go to a nearby hospital. Blood HCG and vaginal ultrasound should be checked and if the result shows ectopic pregnancy, surgical treatment will be required. In conclusion, if you are 45 days pregnant, you should seek medical attention promptly regardless of the cause of bleeding, especially if you are not sure of early intrauterine pregnancy, you should be alert to bleeding caused by ectopic pregnancy.