Prior to fertilization with IVF, the fertilized eggs can be genetically biopsied with preimplantation genetic diagnosis (PGD) to increase fertilization success. Once an embryo grows to a 6-8 cell size, a small laser incision in the egg membrane (zona pellucida) allows safe removal of one of the cells. Every cell in the embryo contains an identical copy of the genome of the entire person. Removal of one of these cells does not harm the developing embryo. A Geneticist then studies the chromosomes in the extracted cells for genetic defects and for a definite analysis of the embryo's gender. Embryos of the desired sex and with acceptable genetics are then placed back into the mother.