**Core Concept**
Uterine souffle is a physiological finding in pregnancy, representing a soft, blowing murmur heard during auscultation of the uterus. It arises from increased blood flow through the dilated uterine vessels, particularly in the second and third trimesters, due to hormonal changes and vascular remodeling.

**Why the Correct Answer is Right**
Uterine souffle is caused by enhanced blood flow through the expanded uterine vessels, which results in a soft, blowing sound resembling a wind. This is due to the increased vascularization of the uterus during pregnancy, especially in the second and third trimesters. The murmur is typically heard in the lower abdomen and is synchronous with maternal heart sounds, not fetal heart sounds. It is a normal finding and reflects physiological changes, not fetal distress or movement.

**Why Each Wrong Option is Incorrect**
Option A: Uterine souffle is not synchronous with fetal heart sounds; it is a vascular murmur, not a fetal heart sound.
Option C: Fetal movements do not cause the souffle; it is a vascular phenomenon, not mechanically driven by fetal activity.
Option D: Uterine souffle is a normal, benign finding and does not indicate fetal distress; fetal distress would present with abnormal fetal heart rate or movement patterns.

**Clinical Pearl / High-Yield Fact**
Uterine souffle is a normal, benign finding in pregnancy, especially in the second and third trimesters, and should not be mistaken for a pathological murmur or sign of fetal compromise.

✓ Correct Answer: B. Is due to increase in blood flow through the dilated uterine vessels