Conditions like Down's Syndrome, which are caused by babies carrying the wrong numbers of chromosomes in their cells, affect about one pregnancy in every 500. There are also many other inherited disorders that run in families but can't be diagnosed without a sample of the developing baby's DNA to test. But obtaining that DNA is risky; pregnant women have to undergo tests like an amniocentesis, where a needle is used to obtain cells from around the baby. When doctors do this, there can be up to a one per cent risk that the woman will have a miscarriage. These tests also cannot be performed until after the 11'th week of pregnancy. A better option would be one that doesn't involve needles and can be performed much earlier. Chris Smith spoke to researcher Sascha Drewlo, who reckons that the same system currently used to do a simple cervical smear test is the answer...