"Pregnant women may soon be able to have a blood test to predict whether their babies are likely to have Downs Syndrome instead of undergoing risky invasive tests scientists said on Sunday.  In a study in the Nature Medicine journal researchers from Cyprus said a trial on  pregnancies using the test which involves analyzing the womans blood to detect DNA differences between the mother and the fetus showed it accurately predicted which fetuses were at risk of developing the syndrome.  Philippos Patsalis medical director of the Cyprus Institute of Neurology and Genetics who led the study said the results were very exciting and the test now needed to be trialed in a larger study of about  pregnancies but could lead to changes in clinical practice within two years.  We believe we can modify this test and make it much easier and simple... and then we can have something ready to be introduced into the clinic he told Reuters in Nicosia.  Downs Syndrome is the most common genetic cause of mental retardation occurring in  out of  live births worldwide.  The risk of having a baby with Downs  which occurs when a child has three copies of chromosome  instead of the normal two  increases sharply as women get older. The risk for a yearold mother is  times that for one who is .  Doctors currently use a test known as amniocentesis to check whether a baby is likely to be born with Downs. This test is generally done at about  or  weeks gestation and involves taking amniotic fluid from the mother by inserting a hollow needle into the uterus.  Since amniocentesis carries a small risk of spontaneous miscarriage  Patsalis put it at around one or two percent  scientists have been looking for new less invasive ways to test for Downs and other potential genetic problems.  Patsalis method takes advantage of differences in the DNA methylation patterns  which are important to control levels of genes  between mother and fetus.  It involves taking a small amount of blood from the mother when she is between the th and th week of her pregnancy and detecting extra copies chromosome  in the fetus by analyzing the maternal blood.  In a small trial Patsalis team were able to correctly diagnose  cases where there were extra copies of the chromosome and  normal fetuses  results they said highlighted its clinical potential.  Such a noninvasive approach will avoid the risk of miscarriages of normal pregnancies caused by current more invasive procedures the scientists wrote in their paper.  Writing by Kate Kelland editing by Matthew Jones Our StandardsThe Thomson Reuters Trust Principles. httpthomsonreuters.comenaboutustrustprinciples.html"