What does the amnion do during pregnancy?

The amnion is a crucial structure during pregnancy, as it forms the amniotic sac, which surrounds and protects the developing fetus. This fluid-filled sac serves several important functions, including cushioning the fetus from physical trauma, allowing for movement which is essential for musculoskeletal development, and providing a stable temperature environment. The amniotic fluid also plays a vital role in lung development as the fetus inhales and exhales the fluid, simulating breathing movements. By being the membrane that encases the amniotic fluid, the amnion is directly responsible for maintaining the safety and well-being of the fetus throughout gestation.

Other options may touch on aspects of pregnancy but do not accurately reflect the primary function of the amnion. For instance, while brain development and hormonal production are significant in the context of pregnancy, they are not directly related to the role of the amnion. Similarly, maternal circulation is an essential aspect of pregnancy but is not a function of the amnion itself.