Sex selection
Sex selection |
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Background
Sex selection, also known as gender selection, is any practice, technique or intervention intended to increase the likelihood of the conception, gestation and birth of a child of one sex rather than the other (1). It has generated great interest and controversy, being associated with a number of ethical, moral, social and legal issues. Sex selection may be performed for medical reasons to avoid sex-linked diseases or for family balancing purposes. The on-going controversy surrounds the right of a couple be free to choose the sex of their child and the potential effect of family balancing on society.
Reasons for sex selection
Sex selection is done for medical and non-medical reasons.
Medical reasons
Sex selection is performed to prevent the birth of children of particular sex who are predisposed to inheriting serious genetic abnormalities (essentially sex-linked defects) from parents. These abnormalities include Haemophilia, Huntington's chorea and Duchenne’s Muscular Dystrophy. Sex selection for medical reasons is acceptable in the United Kingdom, following a 2003 Court of Appeal judgement that gave a family the go-ahead to have a child by in-vitro fertilisation (IVF) to provide a life-saving bone marrow transplant for their son who suffers from B-Thalasaemia major. Sex selection for medical reasons is also acceptable in the USA and Australia.
Non-medical reasons
There are families with children predominantly of one sex and for family balancing purposes, desire a child of the other sex to complement the existing family. Other reasons are cultural or financial with some people preferring one sex above the other e.g. family name continuity, inheritance of land or title and payment of dowries.
Sex and the Law
The Human Fertilisation and Embryology Authority (HFEA) regulations allow sex selection only on medical grounds. Most countries prohibit the use of sex selection for non-medical reasons. HFEA regulated centres are prohibited from performing sex selection for non-medical reasons. Gender selection by sperm separation and intrauterine insemination using the partner’s sperm is performed in a number of non-HFEA regulated centres in the United Kingdom. The use of sex selection for non-medical reasons is permitted in the United States, India and Jordan. There is no documented adverse effect or reported unwanted consequences of the use of sex selection but it may be premature to assume there will be none.
Methods of Sex Selection
Preconception method:
Preconception sex selection involves separating sperm-bearing X and Y-chromosomes, a process called “sperm sorting”. This technique exploits the fact that sperm carrying the Y male chromosome is smaller and faster than the female chromosome X. It is done using either the gradient method combined with “swim up” where the sperms swim through a differentiating medium, or the flow cystometry method, where fluorescent dye allow the sperm to be separated subsequently using a laser. Either of these methods allows the identification and separation of sperms carrying the X and Y chromosome, that are used for artificial insemination or In-vitro fertilization (IVF) of the oocyte. The current method of choice is microsoft sperm separation.
Preconception sex selection has an accuracy rate of 80-90% for X-chromosomes, and 60-70% for Y chromosome. The advantage of this technique is that the enriched sperm, can in principle be used for artificial insemination, and as such is not as invasive as IVF. In addition, it reduces the production of embryos of unintended sex that might end up being destroyed. It is not as expensive as the other methods.
Preimplantation genetic diagnosis (PGD):
Embryos created by IVF are tested using Fluorescent In-Situ Hybridisation (FISH) or Polymerase Chain Reaction (PCR) techniques to
select those of a particular sex before being transferred into the woman. This is a more reliable way of determining sex of offspring with a relatively low misdiagnosis rate of less than 1% on the average. It is expensive and invasive, with women facing the risks associated with hormone stimulation and invasive egg collection. Embryos of the desired sex are transferred into the uterus while those that are not of the required sex are discarded.
Post-implantation (prenatal testing) method:
This method involves prenatal testing of the embryo or fetus, using ultrasonography, amniocentesis or chorionic villous sampling (CVS). Ultrasonography is a non-invasive technique but is not as reliable as invasive tests such as amniocentesis and CVS. However, these invasive tests are associated with a risk of miscarriage of 1-2%.
Fetuses determined to be of the unintended sex are aborted. This is the oldest method of sex selection. Abortion on grounds of sex selection is illegal in the United Kingdom and infanticide is a criminal offence. Post implantation method is highly invasive and may have psychological and gynaecological complications.
Periconceptual method:
Periconceptual choice of sex is based on the observation that conception close to ovulation is more likely to result in a boy. Attempts to predict the time of ovulation have been made by measuring hormonal levels (2), polarity of the egg membrane (3), and cervical mucus thickness. Other “folklore” methods include positioning during intercourse and vaginal douching (4). These methods are commonly employed throughout the world, but their effectiveness is questionable. Preconception method has no apparent health risk. It provides couples with a five to six times greater chance of having a girl rather than a boy. It is about 85% effective at producing a girl, and 65% effective in producing a boy (5).
Impact of Sex selection
The long-term effects of the techniques for pre-implantation genetic diagnosis are uncertain (6,7). A recent study found out that there is an increased risk of congenital abnormalities in the group of children conceived through IVF and Intra Cytoplasmic Sperm Injection (ICSI) compared to naturally conceived children (8). It has been suggested that the practice of sex selection would probably reinforce sexist attitudes both in those who practice it and in others (9). There may be instances where the prospective parents desire to undertake the procedures as an expression of sex prejudice. Such attitudes are an affront to the notion of human equality and are especially inappropriate in a society fighting to rid itself of a heritage of such prejudices.
Quality of life arguments have also been advanced as reasons for sex selection. Sex choice is said to enhance quality of life more for a child of the wanted sex than a child of the unwanted gender. It is believed to provide better quality of life for the family that has the balance it desires. It would provide a better quality of life for the mother, because she will undergo fewer births to have the desired number of children of each sex (10).
Evidence exists that most people who want a child of each sex prefer to have a male first, and that firstborn children are likely to achieve more than subsequent children (11). Thus, if couples use sex selection to have a male child first, the advantages of being first-born could go predominantly to men and in turn, men on the whole might be better social achievers than females. In addition, given the evidence of preference for male children, there is concern that sex selection might upset the male-female ratio in the population in the direction of a male-dominated society as in China (1).
Sex selection of children seems incompatible with the attitude of unconditional acceptance that developmental psychologists have found to be essential for successful parenting (11). Sex selection might have a negative psychological impact on children themselves. Children who are sex-selected could feel subtly harmed, controlled, or invidiously different from other children not so conceived. If a daughter knows that she was “planned-to-be-second”, she may suffer a loss of confidence or self esteem. When a daughter is first born, she may be damaged if she learns that whereas she was not sex-selected, her younger brother was. Moreover, there is the possibility that a given method of sex selection may fail, with the child of the unwanted sex experiencing parental rejection or developing feelings of inadequacy. There is a possibility that use of procedures to select the sex of children will set a precedent for selecting other characteristics which may have nothing to do with a medical condition in children and we end up with “designer children”. In fact, this raises the question on the use of medical technology for non-medical purposes. Such a use simply to facilitate the wishes of the consumer is the slippery slope mentioned in the HFEA document. Other potential harms which may arise from this practice, if used for non medical reasons include: the perpetuation of inequalities, stereotypes, power relations, both within countries and between countries, especially now that the access to this genetic technology is dependent on wealth.
Conclusion
Sex or gender selection is a useful medical advancement in the field of Assisted Reproductive Techniques and will increasingly become available as an intervention to solve medical problems. However, law should strictly regulate its use.
References
1. Human Fertilisation and Embryology Authority document on Sex Selection.
2. Carter H. Couple buy a baby girl to order. Herald Sun (Melbourne) 1998; Sept 12:9.
3. Carter H. Pick the sex test. Herald Sun (Melbourne) 1999; May 5:5.
4. Carson SA. Sex Selection: the ultimate in family planning. Fertil Steril 1988; 50: 16-19.
5. Fugger EF, Black SH, Keyvanfar K, Schulman JD. Birth of normal daughters after Microsort sperm separation and intrauterine insemination, in-vitro
fertilisation, or intracytoplasmic sperm injection. Hum Reprod 1998; 13:2367-2370.
6. Dulious E, Toyama K, Bushel MC, et al. Long term effects of embryo freezing in mice. Pro Natl Acad Sci USA 1995; 92: 589-593.
7. Wennerholm UB, Albertson WK, Bergh C, et al. Post natal growth and health
in children born after cryopreservation as embryos. Lancet 1998; 351:1085-1090.
8. Simpson JL. & Lamb DJ. Genetic Effects of Intracytoplasmic Sperm Injection. Semin Reprod Med 19(3):239-249, 2001.
9. Benagiano G, Bianchi P. Sex preselection: an aid to couples or a threat tohumanity? Hum Reprod 1999; 14: 868-870.
10. Wertz DC & Fletcher JC, Fatal Knowledge? Prenatal Diagnosis and Sex Selection, Hastings Center Report, May/June 1989, p. 22.
11. Bayles M. Reproductive Ethics, 1984, pg 36.
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