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.
Signs and tests
Your health care provider can diagnose placenta previa with an ultrasound exam. Most cases of placenta previa are identified by routine ultrasound during pregnancy.