Gender or sex selection is the ability to choose the gender or sex of your child before you become pregnant. Two chromosomes, namely the X and Y chromosomes, determine the sex of your child. One is inherited from the mother and one is inherited from the father. The egg from the mother carries an X chromosome and the sperm from the father carries either an X or a Y chromosome. If the egg is fertilized with an X- bearing sperm, the resulting XX embryo will be female. If the egg is fertilized by a Y- bearing sperm, the resulting XY embryo will be male. Typically, there is a 50/50 chance of conceiving either a female or a male child. In vitro fertilization (IVF) in conjunction with Preimplantation genetic diagnosis (PGD) and blastocyst biopsy can predict with an almost 100% accuracy the sex of the child prior to performing the embryo transfer.
There are two primary reasons for considering gender selection:
Genetic Disease: Some couples have certain genetic diseases that they do not want to pass on to their children. Examples of X-linked diseases that would result in male children being affected include hemophilia and muscular dystrophy. In these cases couples choose to have a female child.
Family Balancing: Couples who already have a child of one sex may turn to fertility treatment to have another child of the opposite sex. Conversely, there may be cultural reasons for having a child of a specific gender.