A doctor in Belgium is allowing parents to pick the gender of their childbefore it has even been conceived, writes Susan Carroll.

Boy or girl? Well, you choose. That's just what the first couple in Europe to have a child using a controversial gender selection technique have done. The little girl was born in February, and, according to the Belgian doctor behind the service, is in good health.

In his private clinic in the quaint Flemish town of Ghent, Prof Frank Comhaire has been quietly offering parents the chance to choose the gender of their children since December 2001. A full-time andrologist at Ghent University Hospital, he's been working with infertility problems for more than 20 years.

So far, says the genial doctor, 50 to 60 couples have come to him about the technique. Some 15 have gone, or are going through the entire process, which is performed in connection with US-based firm MicroSort.

The technique works by sorting sperm by size: separating the smaller ones bearing the male (Y) chromosome from the larger ones carrying the female (X) chromosome.

Samples taken in Belgium are frozen and sent to the MicroSort labs in Fairfax, Virginia. After sorting, they are re-frozen and returned. After analysis to make sure they're healthy, the woman undergoes in vitro fertilisation (IVF) at another Ghent clinic.

The entire process costs €6,300. Add in the cost of the one-and-a-half hour flight to Brussels and 30-minute train ride to Ghent, and Irish couples could be having little girls or boys made to order for a relatively low price.

It's not quite as simple as it sounds, though. Comhaire only offers the service to married couples who already have one child and want another of the opposite sex - so-called family balancing. The procedure, which takes between four and six months, must be finished by the time women turn 40.

In his small office at the hospital, the doctor says that one of the couples he's working with has nine daughters and another has six boys. Parents are carefully vetted, he stresses, showing me a sheaf of paperwork they must fill out during their initial 40-minute consultation. There is also blood and semen analysis, and MicroSort performs another interview by telephone before the sorting takes place.

The pre-conception technique is legal in Belgium, and Comhaire is adamant that it is safe, despite being in its early stages. In the US, there have already been around 330 births after conception using this technique.

"Some 200 of those babies are now more than a year old, and there has not been an increased proportion of congenital abnormalities," he says.

MicroSort's work is part of a clinical trial approved by the US Food and Drug Administration. It recently allowed the number of couples taking part in the trial to be increased to 3,500, which is likely to result in 1,000 births (IVF success depends on a number of factors, including age).

Sex selection is used in Britain and the US to avoid genetic conditions passed on to one gender, such as haemophilia in males. Comhaire is offering it for purely social reasons, although he claims family balancing has medical merit.

"Medicine is more than just treating diseases, it's intended to prevent diseases and promote health. And health is mental as well as physical. If we can improve the well-being and the health of couples and their children by fulfilling their profound and serious desire to have a child of the other gender, we are performing a medical act."

The doctor scoffs at the notion that this is the first step towards designer babies. Why, he asks, is it ethically acceptable to choose whether or not to have a baby by using contraceptives, but not to select the sex of a child?

"Only the gender aspect of birth is decided by chance. But has chance a higher ethical value than choice? As humans, we say that we are superior to other animals because we can make choices. Almost everything we do is by choice. Choosing the gender of children is the only case where chance has a higher ethical value than choice."

The procedure does not alter genetic material. "We don't touch the embryos. We work on cells which could never generate a human being by themselves," he says. Indeed, sperm is not accorded the same legal protection as embryos. However, part of the Irish Commission on Assisted Human Reproduction's remit is to examine the regulation of the freezing and subsequent use and disposal of sperm.

It is unlikely the technique will be offered in Ireland soon.

"We just don't believe in eugenics for trivial reasons, which is why we don't practise gender selection here," explains Prof Robert Harrison of the Royal College of Surgeons, who is a director of the Human Assisted Reproduction Ireland unit at the Rotunda Hospital, which helps infertile couples.

Dr Tony Walsh, medical director of the Sims Fertility Clinic in Dublin, likens Comhaire's family balancing to designer families, rather than designer babies.

"It is a much more reasonable way to approach gender selection than performing ultrasounds and aborting children of the unwanted sex, which I find abhorrent," he says.

But, he adds, under Medical Council guidelines in Ireland the procedure would not be permitted.

The technique is 88 per cent accurate if you want to have a female child, like most of Dr Comhaire's clients, and 75 per cent accurate for a male child. When the sperm comes back after sorting, the couple is told the exact proportion of X- and Y-bearing sperm in their sample. "It's up to them whether they want to proceed," he says.

To be completely sure, a pre-implantation genetic diagnosis can be performed - for an extra €3,000. While this cannot be done purely for sex selection reasons under Belgian law, Comhaire's clients tend to be nearing 40, so testing can be done for conditions such as Down's syndrome - and the gender noted along the way.

Gender selection is unlikely to become a high-street medical procedure, believes the doctor.

"The process is quite time-consuming and relatively onerous. If it was as easy as filtering your own sperm, everybody would be using it. As it is, you must have strong motivation to go through with it." Comhaire says this is why the technique only appeals to a minority of people - and it will not upset the balance of the sexes.

Dr Comhaire offers complete confidentiality to his clients and refuses to answer any questions that might identify them - saying only that they believe having children of both genders will make their lives richer and more fulfilling.

"Unless you speak to these people, you can't understand how they feel," he adds. He will only reveal that the parents come from all over Europe.

A couple of day trips to Ghent and no one at home need ever know that you knew whether to buy pink or blue clothes, before the baby was even conceived.