Nature press release Embargoed until: 26 October, 2005 13:00 U.S. Eastern time, 18:00 London time , 27 October, 2005 02:00 Japanese time | 03:00 Australian Eastern time Trial aims to measure social effects of choosing babiesÕ sex By Erika Check WASHINGTON DC -- U.S. doctors have launched a clinical trial to assess the effects of allowing couples to select whether they will have a boy or a girl. Doctors can use a technology called preimplantation genetic diagnosis (PGD) to examine the sex of embryos that they create by assisted reproduction. Couples then select male or female embryos to implant in the motherÕs uterus, but the practice is controversial and banned in a number of countries. Sandra Carson and two colleagues at Baylor College of Medicine in Houston, Texas, started their trial last month, after nine years of consultations with their institutional review board. The doctors have a waiting list of at least 50 couples, but they will only enroll those who already have a child, and want to have a child of the opposite sex -- an approach referred to as Òfamily balancingÓ. An experimental technique called sperm sorting is currently being tested to see whether it can reliably create embryos of a desired sex. But Carson says no one has examined what happens when couples use PGD, a more established tool, to choose an embryoÕs sex for nonmedical reasons. The practice, known as Òsocial sex selectionÓ, is thought to be common in the United States. One study found that almost 3% of PGD procedures, which are performed thousands of times a year, were used to choose a childÕs sex. But countries such as Britain and Canada have banned the practice owing to public concerns that it could lead to discrimination against women. ÒThere are still a lot of questions in peopleÕs minds about whether this is something that should be pursued,Ó says Robert Brzyski, a fertility doctor at the University of Texas Health Science Center in San Antonio. Brzyski says he does not offer social sex selection at his clinic because it contradicts the idea that a child should be unconditionally loved, regardless of its sex. ÒIt undermines the principles of the parentÐchild relationship,Ó Brzyski says. The United States does not regulate social sex selection, but in the past few years two professional societies, the American Society for Reproductive Medicine (ASRM) and the American College of Obstetricians and Gynecologists (ACOG), have issued statements opposing it. A spokesman for the ASRM, Sean Tipton, says that the society has no comment on the trial that Carson is running. However, Tipton says, Òwe can sanction and remove members who donÕt obey ethics statements.Ó Carson thinks her study, which will look at the health of the babies born as well as social factors in the families as the children grow up, could convince the ASRM and ACOG to revise their position. ÒTheir statements are based on public opinions, not outcomes,Ó Carson said at the ASRM meeting in Montreal on October 18. ÒPublic opinion is important, but it shouldnÕt be used to ban something.Ó /ENDS Nature Publishing Group© 2005