When you are pregnant in the third trimester, a little blood in the leukorrhea may be the cause of preeclampsia, hyperemesis gravidarum, embryonic abruption, etc., which need to be analyzed specifically. 1. Pre-eclampsia: when there is less progesterone in the pregnant woman’s body, it will lead to abnormal contraction of the uterus, which will affect the stabilization of the fetus and lead to the occurrence of pre-eclampsia. 2. Hyperemesis gravidarum: If hyperemesis gravidarum exists, there will be meconium-like material discharged, accompanied by vaginal bleeding, and mixed with leukorrhea, which will lead to blood in the leukorrhea. 3. Embryonic arrest: If the fetus stops developing in the uterus due to chromosomal abnormality or other reasons, it will lead to the shedding of pregnancy tissues and bleeding, which is manifested as blood in the leukorrhea. If there is blood in the leukorrhea in pregnancy, it is an abnormal phenomenon, and you need to consult a doctor in time and take standardized methods under the doctor’s guidance to deal with it and promote the alleviation of the condition.