If vaginal bleeding occurs on the 42nd day of pregnancy, the following causes are common in clinical practice:1. Pre-eclampsia caused by luteal insufficiency, it is recommended to determine the intrauterine pregnancy through ultrasound, and then give the treatment of anabolism.2. The embryonic gene deficiency is caused by pre-eclampsia in early pregnancy or the embryo stops developing, most of which is due to the embryonic gene deficiency.3. History of trauma or sexual intercourse. Or there is a history of sexual intercourse, which causes uterine contraction under the action of external force, causing the peeling off between the gestational sac and the uterine wall, that’s why the vaginal bleeding occurs. In addition, bleeding can also be caused by the mother suffering from some serious internal diseases or noise stimulation.