Babies' sex 'a matter of chance'

Couples who have children all of the same sex are simply the victims of chance rather than having a predisposition to conceiving only boys or girls, a study has found.

New research scotches the popular myth that one particular gender runs in families because they have a "boy" or "girl" gene.

The research was presented at the annual conference of the American Society for Reproductive Medicine in Philadelphia.

Scientists from the ART Reproductive Centre in Beverly Hills, California, studied patients who had come forward for fertility treatment involving Preimplantation Genetic Diagnosis (PGD).

PGD is controversial because it involves screening embryos for particular characteristics before they are transferred into a woman's womb.

It can be used to ensure that couples who are carriers or sufferers of rare genetic diseases have healthy babies. But the process can also allow couples to choose the sex of their children by transferring only male or female embryos.

The use of PGD for sex selection or "social reasons" is prohibited by the Human Fertilisation and Embryology Authority in Britain, although it is permissible in America.

Researchers at the Beverly Hills Centre say around 40 couples a year ask for PGD for social reasons, mainly in order to select the sex of their child.

They looked at 10 couples who came forward for the treatment, which resulted in 60 embryos.

All the couples had at least three children of one gender, and wanted to ensure their next baby was of the opposite sex.

The sex of a child is determined by the man's sperm rather than the woman's egg.

Newspaper stories of women having 10 boys or girls have only added to popular perceptions that some couples may be genetically destined to produce same-sex siblings.

But when the researchers screened the fertilised embryos produced from the sperm and eggs of the couples opting for PGD, they found they had equal numbers of male and females.

The scientists said the screening showed that same-sex siblings were not a result of genetics, but simply of chance.

PGD in New Zealand

Preimplantation Genetic Diagnosis (PGD) is likely to be introduced in New Zealand next year. Parents here will not be allowed to use the test to select the sex of their babies.

- INDEPENDENT