A fetus is first called an embryo.
The development of a pregnancy progresses through distinct stages, as outlined below:
- Fertilized Egg: The initial stage begins with the fertilization of an egg.
- Blastocyst: The fertilized egg develops into a blastocyst.
- Embryo: According to the provided reference, after the blastocyst stage, the developing organism is called an embryo.
- Fetus: The embryo eventually develops into a fetus.
