Definition
Placenta previa is a complication of pregnancy in which the placenta grows in the lowest part of the womb (uterus) and covers all or part of the opening to the cervix.
The placenta is the organ that nourishes the developing baby in the womb.
Symptoms
The main symptom of placenta previa is sudden, painless vaginal bleeding that often occurs near the end of the second trimester or beginning of the third trimester. In some cases, there is severe bleeding, or hemorrhage. The bleeding may stop on its own but can start again days or weeks later.
There may be uterine cramping with the bleeding. Labor sometimes starts within several days after heavy vaginal bleeding. However, in some cases, bleeding may not occur until after labor starts.
See: Vaginal bleeding in pregnancy