Supine Hypotension Syndrome is caused by what?

• A. Pressure on the inferior vena cava when lying supine.
• B. Uterine contractions
• C. Placental abruption
• D. Eclampsia

Answer: (A)

Supine Hypotension Syndrome happens when a pregnant person lies on their back and the enlarged uterus presses on the inferior vena cava, which reduces venous return to the heart. This drop in preload lowers cardiac output and can cause maternal dizziness or faintness and fetal distress from decreased placental perfusion. The key is the mechanical compression of the IVC by the uterus in the supine position, and relief comes by turning to the left side (left lateral decubitus) to free the vena cava and restore blood flow. Other choices point to labor or complications like placental separation or seizures, which are not the cause of this posture-related decrease in venous return.