What is the primary symptom of placenta previa?

Bleeding after 20 weeks of gestation is the primary symptom of placenta previa. This condition occurs when the placenta is positioned low in the uterus, partially or completely covering the cervix. As the pregnancy progresses, especially during the third trimester, the growing uterus can lead to bleeding as the cervix begins to dilate or efface. This bleeding is typically painless, differentiating it from other potential complications in pregnancy.

The presence of vaginal bleeding after 20 weeks is a classic presentation in cases of placenta previa, leading to critical evaluation and monitoring for both the mother and the fetus. While other symptoms like abdominal pain or contractions might occur in various pregnancy-related issues, they are not specific to placenta previa and do not serve as the hallmark symptom for this condition. Therefore, recognizing and addressing bleeding is vital in managing placenta previa to prevent complications such as preterm labor or significant blood loss.