What is a likely cause of lightheadedness for a client measured at fundal height during 36 weeks of gestation?

The likely cause of lightheadedness at 36 weeks of gestation is compression of the vena cava. As the pregnancy progresses, the growing uterus can exert pressure on the inferior vena cava when the mother is in a supine position (lying on her back). This compression can hinder blood flow returning to the heart, leading to reduced cardiac output and, consequently, symptoms like lightheadedness and dizziness.

The position of the mother plays a significant role in this scenario; when lying on her back, the weight of the baby and uterus can restrict venous return, particularly affecting blood flow to the upper body and brain. This is often referred to as supine hypotensive syndrome and can cause feelings of lightheadedness or dizziness.

In contrast, while dehydration, anemia, and low blood sugar levels can also lead to lightheadedness, they are less specific for the scenario provided. Dehydration due to nausea may lead to other symptoms as well, and anemia or low blood sugar levels are not necessarily directly linked to the mechanical issues that arise from the compression of the vena cava in late pregnancy.