What physiological change might cause lightheadedness in a client at 36 weeks' gestation?

• A. Increased blood pressure
• B. Compression of the vena cava
• C. Low fetal movement
• D. Inadequate hydration

Answer: (B)

The experience of lightheadedness at 36 weeks' gestation can often be attributed to the compression of the vena cava, specifically the inferior vena cava. As the fetus grows, the enlarged uterus can place pressure on this major vein, particularly when the expectant mother is lying supine (on her back). This compression can restrict blood flow returning to the heart, reducing cardiac output and causing a temporary decrease in cerebral perfusion. This reduction in blood flow to the brain can lead to feelings of lightheadedness or dizziness.

Other potential causes of lightheadedness, such as increased blood pressure or inadequate hydration, typically do not align as closely with the physiological changes occurring in late pregnancy as vena cava compression does. While low fetal movement may raise concerns, it is usually not directly linked to sudden lightheadedness. Understanding how physical changes in the body during pregnancy, particularly those affecting blood circulation, can lead to symptoms is crucial for anticipating and managing the well-being of both the mother and the fetus.