Marginal placenta previa describes a condition in which the placenta attaches lower than usual, next to the cervix. This is a milder form of complete placenta previa, in which the placenta completely covers the cervix. The condition usually corrects itself as the pregnancy progresses, because the stretching of the uterus forces the placenta to move away from the cervix. Until this point, bed rest and frequent doctor appointments are usually advised, as are steroid shots to develop the baby's lungs in case of preterm labor and delivery. The main symptom of marginal placenta previa is vaginal bleeding, usually caused by broken blood vessels, starting in the second trimester.
In most pregnancies, the placenta attaches to the strong upper area of the uterus. When women have placenta previa, the placenta attaches to the lower area, which is thinner and, therefore, weaker. As the cervix stretches during the pregnancy, the lower part becomes even thinner, which often results in bright red blood coming from broken blood vessels. Marginal placenta previa is the mildest form, because the placenta attaches next to the cervix without covering it. The placenta covers part of the cervix in partial placenta previa and covers the entire cervix in complete placenta previa.
Some of the possible complications of marginal placenta previa include anemia and hemorrhaging, which is why women with this condition are often watched closely after labor and delivery. Doctors may also measure the hemoglobin levels of both the mother and her baby after delivery, allowing anemia to be treated right away if it is present. Placental abruption, in which the placenta separates from the uterus, is another risk of marginal placenta previa. This condition can result in the death of the fetus because, without the placenta, he no longer gets oxygen or nutrients from the mother. A risk of placenta previa is preterm labor, which is why doctors may offer pregnant women steroid shots to help develop the baby's lungs if the issue has not corrected itself by the third trimester.
The cause of marginal placenta previa has not been determined, but there are some known risk factors. For example, mothers carrying multiple babies in one pregnancy and those who have given birth before have an increased risk of this condition. Women who have had placenta previa, surgery on the uterus, or a Caesarean section are also at higher risk of placenta previa. Women who smoke and those who are under age 20 or over age 35 also have a heightened risk of this condition.