Placenta previa is a pregnancy condition where the placenta partially or completely covers the opening of the cervix. The cervix is the lower part of the uterus that connects to the birth canal, so when the placenta sits too low, it can block the baby’s path for delivery. Placenta previa is found in roughly 1 in 200 pregnancies that reach the third trimester, and it’s typically discovered during a routine ultrasound rather than because something went wrong.
How Placenta Previa Is Detected
Most cases of placenta previa are identified during the mid-pregnancy anatomy scan, which usually happens around 18 to 22 weeks. During this ultrasound, your provider locates where the placenta has attached inside the uterus. If it’s sitting low or covering the cervix, your provider will note this and plan for follow-up imaging.
It’s worth knowing that an early diagnosis doesn’t always mean the placenta will stay in that position. As your uterus grows throughout pregnancy, the placenta often migrates upward and away from the cervix on its own. Your provider will typically schedule another ultrasound later in pregnancy to check whether the placenta has moved. In many cases, especially when the placenta is only partially covering the cervix, it resolves without any intervention.
Symptoms to Watch For
The most recognizable symptom of placenta previa is painless vaginal bleeding during the second or third trimester. The bleeding can range from light spotting to heavier episodes, and it often happens without any cramping or contractions. Some women with placenta previa don’t experience bleeding at all and only learn about the condition through ultrasound findings.
