London: A pioneering blood test that could allow pregnant women know the sex of their unborn child as early as five weeks has been developed, but scientists have warned that it has potential for promoting sex-selection.
A team led by Dr Hyun Mee Ryu at Cheil General Hospital in Seoul, South Korea, found that various ratios of two enzymes which can be extracted from a pregnant mother`s blood indicate the baby`s gender as early as five or six weeks.
Knowing the sex early, the scientists said, is important if the mother is a carrier of an X-chromosome gene that can cause a disease like muscular dystrophy or haemophilia.
They said that female foetuses are either free from the disease or are carriers, but a male has a 50 per cent chance of inheriting the disease and parents may choose to abort the pregnancy, the Daily Mail reported.
However, this method "might promote the potential for sex selection. Therefore, there should be careful consideration about the use of this analytical tool in clinical situations," the scientists warned.
Current ultrasounds can detect a baby`s sex at around five months, while available invasive testing can work at 11 weeks. But these tests carry a one to two per cent risk of miscarriage as they require a sample from the amniotic sac that protects the foetus.
Writing in the The FASEB Journal, Dr Hyu said their test could "reduce the need for invasive procedures in pregnant women carrying an X-linked chromosomal abnormality and clarify inconclusive readings by ultrasound."
For their study, the team collected maternal plasma from 203 women during the first trimester of their pregnancies between 2008 and 2009. They were able to accurately detect the gender of the baby from as early as five weeks by measuring the ratio of the amount of the enzymes -- DYS14 and GAPDH -- in the blood plasma.
"Although more work must be done before such a test is widely available, this paper does show it is possible to predict the sex of a child as early as the first few weeks after conception," said Dr Gerald Weissmann, editor-in-chief of the journal which published the study.