As previously mentioned, pre-implantation genetic screening of embryos helps determine that an embryo or embryos has the correct or incorrect number of chromosomes. Humans with a normal complement of chromosomes have 23 pairs of chromosomes. There are 22 pairs of chromosomes called the autosomes that determine characteristics other than gender. In addition to these 22 chromosomes, there is a pair of “sex chromosomes” that carry the genetic information that leads to the differentiation of the fetus into a girl or a boy. The Karyotype of a girl is 46 XX while that of a male is 46 XY. The presence of the Y chromosome leads to differentiation into a boy.
Though this process can aid a couple in family balancing, the ultimate goal is to minimize the chance of genetic disorders or conditions being passed on and to help couples conceive and deliver a healthy child.