« Home

Home » Medicine » Young: Medical Genetics » Resources » Case Celebres » Chapter 14

Young: Medical Genetics

Chapter 14

Sex selection

Ethical issues and prenatal diagnosis are considered on page 279. Here it is stated that the traditional non-directive and non-judgemental stance of most medical practitioners and geneticists does not extend to termination because the baby is of the ‘wrong’ sex, as this does not constitute an abnormality. While in general this still holds true, there is increasing evidence that post-conception sex selection is being practised on a massive scale in some parts of the world, most notably in China and in India. This is particularly relevant in China where the traditional pressure to have sons has been exacerbated by compulsory family planning and the government’s ‘one child’ policy.

The normal male to female (M/F) sex ratio at birth is 106 to 100. This tends to approach 1 by adult life because of higher mortality amongst male infants. According to figures from the National Bureau of Statistics, the M/F sex ratio at birth is now close to 117 to 100 in China where approximately one million female pregnancies are terminated annually. This will result in an estimated surplus of around 30 million young adult males by 2020. Similar statistics are emerging from India where the national M/F ratio among children aged 0 to 6 years is 1000 to 927. Sex selection is probably practised more commonly in prosperous urban communities than in the countryside: the M/F sex ratio at birth in Delhi in 2001 was 1000 to 818.

There is some evidence that sex selection is also being carried out, albeit on a smaller scale, elsewhere in Asia in countries such as Hong Kong, South Korea, Taiwan, and Vietnam. Residents of other nations should hesitate to assume any sense of moral superiority. Kits for early sex determination in pregnancy are now being marketed via the internet in the United States, at a cost of $275, and there is concern that sex selection is being offered discreetly at private clinics in many other western countries.

Recent technological developments that can facilitate sex selection will almost certainly make this an even more pressing issue. Sperm selection by cell sorting is offered at some private clinics but at present is not 100% reliable. In contrast, non-invasive diagnosis of embryonic or fetal sex can now be achieved with a high degree of reliability by analysis of free fetal DNA in maternal plasma. (This differs from the use of fetal cells in maternal blood as discussed on page 276). Free fetal DNA constitutes up to 5% of total maternal plasma DNA in early pregnancy. Several studies have shown that PCR based detection of Y chromosome sequences conveys close to 100% sensitivity and specificity as early as five weeks gestation. This forms the basis of home testing kits being marketed in the United States. An alternative non-invasive diagnostic approach involves ultrasonography which can often give an accurate indication of fetal sex from 13 weeks gestation onwards.

The ethical issues surrounding prenatal sex selection are complex and emotive. On the one hand it can be argued that parents are entitled to reproductive autonomy and on occasions it can be very difficult to reject a request for sex selection from a couple with a large number of children of one sex who are desperate to have a child of the opposite sex. In an extreme situation, how should a physician respond when faced with a pregnant woman whose marriage is at risk if she is not able to produce a son/daughter? Is sex selection acceptable when the alternative is termination?

Opponents of sex selection can argue cogently that, as practised in China and India, this is little less than mass genocide. The surplus of partnerless males in these countries will almost certainly have adverse social repercussions in the long term. The point can reasonably be made that sons cannot themselves have sons if there are no available female partners. Legislation may provide a partial solution but it will require a major change in social attitudes before this pressing issue is satisfactorily resolved.

References

Human Fertilisation and Embryology Authority (2003) Sex selection: options for regulation. HFEA, London.

Lai-wan CC, Blyth E, Hoi-yan CC (2006) Attitudes to and practices regarding sex selection in China. Prenatal Diagnosis, 26, 610-613.