What is the name of the period of development from conception to birth within the mother's body?

The correct term for the period of development from conception to birth within the mother's body is gestation. This typically encompasses the entire duration of pregnancy during which the embryo and fetus develop.

Gestation refers specifically to the time it takes for the fertilized egg to grow and mature into a baby ready for birth. In humans, this period generally lasts around 40 weeks. It involves various stages, including the embryonic stage (the first eight weeks after conception) and the fetal stage (the remaining duration until birth).

Other terms, while related to reproduction and development, do not accurately represent this specific period. Incubation typically refers to the development of eggs outside the mother, often in birds or reptiles, and does not apply to human development. Gestational age is a term used to define the age of the fetus or embryo based on the last menstrual period of the mother, but it does not denote the developmental period itself. Developmental phase is a more general term that can refer to various stages of development in organisms and does not specifically relate to the time frame from conception to birth.