**Core Concept**
Placenta accreta is a condition where the placenta invades the uterine wall, leading to abnormal adherence. It is a significant cause of maternal morbidity and mortality. The underlying factors contributing to placenta accreta involve the interaction between the placental bed and the uterine wall.

**Why the Correct Answer is Right**
Uterine malformations, such as bicornuate or unicornuate uterus, do not significantly increase the risk of placenta accreta. The primary risk factors for placenta accreta include previous uterine surgery, such as cesarean sections or myomectomies, which lead to the formation of fibrotic tissue in the uterine wall. This fibrosis can cause the placenta to adhere to the uterine wall more strongly than usual.

**Why Each Wrong Option is Incorrect**
**Option A:** Placenta previa, characterized by the placenta covering the cervix, is indeed associated with an increased risk of placenta accreta. The abnormal placentation in placenta previa can lead to the invasion of the placenta into the uterine wall.
**Option B:** Uterine scars from previous surgeries, such as cesarean sections, are a well-established risk factor for placenta accreta. The presence of scar tissue in the uterine wall can lead to abnormal adherence between the placenta and the uterine wall.
**Option C:** Multiparity, or having given birth multiple times, is also associated with an increased risk of placenta accreta. The repeated distension of the uterus during pregnancy may lead to the formation of fibrotic tissue in the uterine wall, increasing the risk of placenta accreta.

**Clinical Pearl / High-Yield Fact**
It is essential to identify women with a history of uterine surgery or previous placenta accreta, as they are at an increased risk of developing placenta accreta in subsequent pregnancies. Regular prenatal ultrasound and careful monitoring can help identify these cases early on.

**✓ Correct Answer: D. Uterine malformation**