**Core Concept**
Fetal blood loss due to abnormal cord insertion is a consequence of the umbilical cord being attached too close to the fetal body, which can lead to compression of the umbilical vessels and restricted blood flow. This condition can result in fetal hypoxia and acidosis.

**Why the Correct Answer is Right**
Abnormal cord insertion, also known as velamentous cord insertion, occurs when the umbilical cord inserts into the fetal membranes rather than the placental mass. This can cause the umbilical vessels to be compressed or kinked, leading to fetal blood loss and compromised placental perfusion. The resulting fetal hypoxia can have severe consequences, including growth restriction and stillbirth.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because this option is not related to the mechanism of fetal blood loss due to abnormal cord insertion.
**Option B:** Incorrect because this option describes a different condition, placenta accreta, which is characterized by abnormal placental invasion into the uterus.

**Clinical Pearl / High-Yield Fact**
Remember that abnormal cord insertion is a significant risk factor for fetal blood loss and should be identified promptly in prenatal ultrasound evaluations.

**Correct Answer: D. Velamentous cord insertion**