From 9 weeks gestation until delivery, what is the developing human referred to as?

From 9 weeks gestation until delivery, the developing human is referred to as a fetus. This stage is characterized by significant growth and development of the body's systems and organs after the embryonic stage, which lasts from fertilization until the end of the 8th week of gestation. During the fetal stage, all major organs are formed, and the fetus continues to mature in preparation for birth.

The term "embryo" specifically applies to the developing human from fertilization until the end of the 8th week, after which the term changes to "fetus." The term "baby" is generally used to refer to a newborn after delivery. "Zygote" refers to the fertilized egg immediately after sperm and egg unite, which is the earliest stage of development and occurs prior to implantation. Thus, the designation of "fetus" accurately describes the development from 9 weeks gestation onward, signifying that the organism is no longer in the embryonic phase and is now undergoing more complex development processes.