With partial or traditional surrogacy, the surrogate is at the same time the birth mother and the biological mother of the baby born as a result. She is inseminated via intrauterine insemination (IUI) in order to make the technical process easier and reduce the number of side effects in the surrogate. In vitro fertilization can be used in traditional surrogacy arrangements, too, although less commonly.
In short, traditional surrogacy is rarely the option of choice, as it translates into the surrogate being genetically linked to the child.
Today, gestational or full surrogacy arrangements are the most commonly used because the gestational carrier (GC) has no genetic link to the child: It is the intended mother or, if not possible, an egg donor who contributes the eggs that will be fertilized in the lab.