Here you shall find a clarification of the different stages of fetal growth, from the very first stage, called zygote, to the last phase, in which it is known as fetus. It will be called this way up until childbirth.
Some assisted reproductive techniques, such as in vitro fertilisation (IVF) or ICSI, perform egg fertilisation outside the woman’s body. For this reason, embryo culture is necessary up to the day in which the embryo transfer is performed.
Embryos can be classified in 4 categories –from A to D– ranging from best quality to least developed embryos. This classification is mainly visual and rather subjective, but there are also several studies to identify their metabolic activity.