Sex selection: choice and responsibility in human reproduction ...

Sex Selection: Choice and Responsibility in Human ReproductionPart Three: Methods Of Sex Selection17. The sex of offspring is determined by the chromosomes (carrying genes or DNA)that are present in the nucleus of every cell in the body. Human cells contain 46chromosomes: 22 pairs (one of each pair coming from each parent) plus two ‘sexchromosomes’, denoted X and Y.18. An egg produced by a woman during her monthly cycle always contains an Xchromosome. Sperm produced by a man contains either an X or a Y chromosome.When a sperm fertilises an egg to produce an embryo, the resulting embryo will beeither XX (female) or XY (male). 3919. Usually fertilisation occurs naturally in the woman’s body after sexual intercourse.However, particularly when people are having trouble conceiving (infertility),embryos may also be created in a laboratory and then transferred to the womanwhen they are a few days old. At this stage the embryo is made up of only a smallnumber of cells and is still invisible to the naked eye. This is in vitro fertilisation(IVF).20. Broadly sex selection may be performed at three different stages:or●●●before fertilisation takes place and an embryo is conceived (pre-conception)after fertilisation outside the body but before the embryo is transferred to thewoman and a pregnancy is established (preimplantation)after a pregnancy is established (post-implantation)21. It will be important later on, when it comes to evaluating the uses of sex selection,to be clear about the exact nature of the choice that is being made with eachmethod. When one thinks of sex selection one has to be careful not to committhe fallacy of thinking that by using these techniques one is choosing the sex of ‘anembryo’ or ‘a child’. The techniques do not affect the sex of embryos or children whoalready exist: the choice is either about which embryos will be created in the firstplace (sperm sorting) or about which embryos, from among those that already existwill be transferred (PGD).3There are certain rare chromosomal abnormalities, which vary in severity, when people have more or fewerthan two sex chromosomes. These can be detected through preimplantation genetic diagnosis.Human Fertilisation and Embryology Authority