GENDER SELECTION (SEX SELECTION)
Gender selection refers to the determination of the desired gender prior to implantation of the embryo. The odds of having a boy or a girl are almost 50/50 in a natural conception cycle and dependent on the sperm. The egg has 22 chromosomes plus the X chromosome, and the sperm brings another 22 chromosomes with either an X or a Y chromosome. If the sperm that fertilizes the egg has a Y chromosome, the end result is a boy and a girl if sperm contains the X chromosome.
Historically, gender selection was offered to patients with genetic diseases that are more common in one gender versus the other. X-linked disorders refer to diseases that are gender specific and can be limited with the process of gender selection. Family balancing on the other hand is a more recent and relatively common request for gender selection. Patients typically desire a method of gender selection that offers them an almost 100% chance of obtaining the desired gender. Whereas sperm sorting has been an option to select sperm with the desired gender, this technology is not considered reliable and thus no longer offered.
PGD is the testing process that can provide the answer. In PGD, one cell is removed from the early stage embryos, and DNA based genetic analysis is performed in highly-specialized laboratories. Upon completion of the analysis which takes approximately 24-36 hours, couples can select which embryos they will transfer. If pregnancy results, there is 99.9% chance it will be of the desired gender.