An unborn baby is called a fetus once it reaches a specific stage of development.
Fetus: The Unborn Offspring
The term fetus refers to an unborn offspring during its development within the uterus. It is the stage of prenatal development that follows the embryonic stage.
Developmental Stage
- In humans, the fetal period begins at 9 weeks after the fertilization of an egg by a sperm.
- This phase continues until the time of birth.
- During the fetal period, significant growth and maturation occur.
Key Characteristics of the Fetus
- The fetus develops and grows inside the uterus of humans and other mammals.
- The fetal stage marks a period of rapid growth and refinement of organs and body systems.
- Major structures such as the limbs, heart, and brain become more defined and functional.
Example:
Imagine a baby developing inside their mother's womb. After the first 8 weeks, when the baby is considered an embryo, the baby is referred to as a fetus. This stage is crucial as the baby's organs continue to grow and prepare for birth.
| Term | Definition | Timeline |
|---|---|---|
| Fetus | Unborn offspring during the period after the embryonic stage | Begins at 9 weeks post-fertilization and ends at birth |
