Some parents-to-be are desperate to decide the sex of their new baby.
A boy or girl - who should decide?
Under current UK law this is not allowed, except in order to avoid gender-linked diseases, such as haemophilia and muscular dystrophy.
In this week's Scrubbing Up bioethicist Stephen Wilkinson argues that it's time for the law to change.
For millennia, people have sought to influence the gender of their offspring and there are numerous folk myths about, for example, the effect of different sexual positions or foods on your baby's sex.
Nowadays there are some much more reliable methods, like preimplantation genetic diagnosis (PGD). This involves creating several embryos outside the body and implanting only male or female ones.
Another option is sperm sorting, which involves dividing a sperm sample into 'male' and 'female' subgroups.
In some other parts of the world, sex selection is available on demand, provided that you are able and willing to pay for it.
In the UK, it is not.
A ban on sex selection may well be justified in counties like China and India where the predominance of son-preference has already led to a significant shortage of girls.
But the available evidence suggests that, in Western Europe, the number of parents preferring boys is roughly the same as the number preferring girls.
As well as concerns about population sex ratio, people often cite moral objections to sex selection, like saying children should be regarded as "gifts" meaning there should be no attempt by parents to pick and choose their characteristics.
Others say sex selection is sexist and that allowing it here would make it harder for governments in places like China and India to resist.
All of these arguments can be countered.
A right to choice
Firstly, should parents regard their children as 'gifts'? Children are not literally gifts, or if they are, from God perhaps, then they are no more gifts than other positive things in life.
Yet we don't, in general, say that it's wrong to attempt to shape life's positive things by, for example, choosing a career, or a house, or a partner.
Secondly, sex selection is not necessarily sexist. While there are no doubt some prospective parents who think that men are superior to women (or vice versa), for most the choice is just a preference.
A pertinent example here is what's called family balancing - where a family that already has three boys wants to add a girl to even things up.
Finally, the fear that allowing sex selection here would open the floodgates elsewhere is unfounded.
This argument takes far too seriously the influence of British policy on the behaviour of Chinese and Indian sex selectors, many of whom are acting outside even their own laws.
Sex selection in China and India is already happening on a grand scale anyway, despite the fact that the UK does not allow 'social' sex selection.
Our 'setting a good example' by prohibiting sex selection does not seem to be making much difference. So, while I am not a sex selection enthusiast, and certainly don't think that it should be encouraged or paid for by the NHS (except to avoid sex-linked disease) the arguments for prohibiting it are not as strong as they may at first appear.
There is real cost and harm attached to the ban: some people are distressed by not being able to have the family of their choice, while others are forced to turn to seeking treatment overseas.
I believe that we should allow sex selection in the UK within the context of our carefully regulated reproductive medicine sector.