During which period of human prenatal development does the fetus become physically active?

The fetal period is the stage of prenatal development that spans from the ninth week after conception until birth. During this time, the fetus undergoes significant growth and development, including the formation of bodily systems and structures. It is during this phase that the fetus becomes physically active, developing muscle tone and engaging in various movements, such as kicking and stretching. This increased physical activity is essential for the development of the nervous system and helps to prepare the fetus for life outside the womb.

In contrast, the germinal period, which lasts from conception to about two weeks, is mostly characterized by cell division and implantation in the uterine wall, with no notable physical movement. The embryonic period, occurring from the third to the eighth week, involves critical development of major organs and structures, but the fetus is not yet physically active in a way that is perceptible. The neonatal period begins after birth and is not part of prenatal development. Therefore, recognizing that the fetal period is where significant physical activity occurs is key to understanding prenatal development.