Which third trimester complication occurs when the weight of the fetus compresses the inferior vena cava when lying supine?

• A. Preeclampsia
• B. Supine hypotensive syndrome
• C. Nuchal cord
• D. Prolapsed cord

Answer: (B)

Supine hypotensive syndrome is being tested here. In the third trimester, lying on the back allows the heavy uterus to press on the inferior vena cava, which lowers venous return to the heart and reduces preload. The result is maternal hypotension and decreased placental perfusion, which can cause dizziness, fainting, and fetal distress. The key clue is that relief occurs when the patient is placed on the left side, which shifts the uterus off the IVC and improves blood flow. This differs from other conditions: preeclampsia involves new hypertension and proteinuria, a nuchal cord is a loop around the fetus’s neck, and a prolapsed cord occurs when the cord slips ahead of the presenting part and can cause sudden fetal compromise.