Which function is NOT attributed to the amniotic sac?

The amniotic sac is a crucial structure in prenatal development, primarily serving to protect and support the developing fetus. The function that is typically not attributed to the amniotic sac is the facilitation of nutrient exchange. While the amniotic sac and its fluid play important roles in providing a cushioning environment and maintaining temperature, nutrient exchange primarily occurs through the placenta, which connects the fetus to the mother's circulatory system. The amniotic fluid supports the fetus's movement and helps prevent compressive injuries, but it does not directly provide essential nutrients to the fetus. Thus, the statement regarding nutrient exchange being a function of the amniotic sac is not accurate.