Marginal placenta praevia is the most common type of placenta praevia generally refers to the lower edge of the placenta approaching the endocervix of the uterus, usually within 2 cm, after 28 weeks of gestation. When the mother has contractions or is active, it can cause abruption between the placenta and the uterus, which can cause bleeding. Marginal placenta praevia is one of the most common causes of antepartum bleeding during pregnancy. If the timing of finding a borderline placenta praevia is before 28 weeks, do not rush yet, there are many chances to grow upwards. As the uterus pulls upward, it will be relatively safe after it exceeds the distance of 2 cm from the inner cervical opening. If there is irregular vaginal bleeding in late pregnancy or after activity, you need to investigate if there is a problem with the placenta, which is a common cause, and you need to go to the hospital for an ultrasound. If the problem does exist, the doctor will advise accordingly and make a recommendation to terminate the pregnancy at the right time.