How often do placenta previas detected in the first trimester resolve before the second trimester?

Placenta previa is a condition where the placenta is abnormally positioned low in the uterus, covering part or all of the cervix. It can be detected through ultrasound in the first trimester, and the likelihood of resolution as the pregnancy progresses is notably high. Evidence suggests that approximately 90% of cases diagnosed as placenta previa in the first trimester will resolve by the time the woman reaches the second trimester. This resolution generally occurs as the uterus expands and grows, causing a change in the position of the placenta.

While it is important to monitor all cases of placenta previa, the high resolution rate can provide reassurance to patients diagnosed in early pregnancy. The correct answer reflects the substantial likelihood—90%—that many initially detected cases of placenta previa will no longer present as an issue later in the pregnancy, emphasizing the dynamic nature of placental positioning.