Unless a surrogate mother intends to use her own egg (and thus be biologically related to the child), pregnancy can only occur through in vitro fertilization, or IVF. The first step in the process: creating and retrieving the egg. This typically involves the stimulation of the ovaries of the future child's mother (not the surrogate mother) using some type of fertility drug. In this way, the woman's ovaries produce a number of eggs, which a physician will then retrieve during a surgical procedure known as transvaginal ultrasound aspiration. The procedure is simple: the doctor removes the eggs from the ovary using a needle-like suction device. The eggs are then placed carefully into an incubator.
The father is then required to give the doctors a certain amount of his sperm. The sperm is separated from the semen and then placed into the incubator with the eggs from the mother. It typically only takes a few hours for fertilization to occur. The fertilized eggs are generally observed for a few days--perhaps two or three--before the next step in the process takes place: transfer to the surrogate mother.
The embryo or embryos that are the result of the fertilization are then placed in a drop of fluid--providing great cushion--then sucked gently into a syringe tube. The tube is inserted into the vagina of the surrogate mother and all the way into the surrogate's uterus. The surrogate then remains in a state of rest for several hours, allowing for the embryo to settle in its new home as easily as possible. The goal: for the embryo to attach itself firmly to the wall of the uterus (called implantation). If this happens, the surrogate mother can officially be labeled pregnant.