Transitioning from the embryonic stage, the fetal stage extends from the ninth week until birth. It is characterized by a period of growth and increasing complexity, as the size and functionality of organs greatly advance.
By the third month, every vital organ is present and development shifts focus to maturation. This includes the refinement of **organ systems** so they can support life post-birth. The fetal stage is also when movements first occur, indicating the development of the muscular and nervous systems. Here's a brief look at what happens during this stage:
- **Organs mature:** Organs begin functioning in unison, preparing the fetus for independent survival.
- **Bone structures:** The skeleton continues to harden, replacing much of the earlier cartilage.
- **Senses develop:** The fetus begins to respond to sound and light stimuli.
The culmination of the fetal stage is the birth-ready infant, equipped to exist outside the womb if full-term.