Complete previa - The placenta completely covers the cervix. Partial previa - The placenta covers a portion of the cervix, but does not completely cover the cervix. Marginal previa - The placenta extends to the edge of the cervix but does not cover it. This can also be called low placental implantation. What is the cause of placenta previa?
The cause of placenta previa is unknown.
Am I at risk for placenta previa?
Placenta previa occurs in about 1 in 200 births. Risk factors include: * previous history of placenta previa
* multiple births
* having given birth before (second or greater pregnancy) * smoking
* over the age of 35
* surgery of the uterus
* prior delivery of a baby via cesarean section
* history of uterine abnormalities
Symptoms of placenta previa
Vaginal bleeding after 20 weeks of pregnancy is the primary symptom of placenta previa. Bleeding during pregnancy may have another cause, however, it is important to call your doctor if you experience bleeding. The placenta normally attaches to the upper portion of the uterus which is more muscular and stronger to support the placenta. However, in placenta previa the placenta attaches to the lower portion of the uterus which is weaker, thinner, and more vascular. As you enter your second and third trimester, the cervix begins to thin and stretch in preparation for labor. As this area stretches it can cause the villi (blood vessels) to break therefore causing bleeding. Placenta previa can...