What is prenatal diagnosis?
Couples at risk of having children with a serious genetic condition may decide to have a prenatal – ‘before birth’ – test. To obtain a sample from a fetus, doctors can carry out either chorionic villus sampling (CVS) at 10–12 weeks of pregnancy or amniocentesis at 14–15 weeks. Both techniques provide enough DNA for genetic testing. If the test results indicate that there is a high risk of the fetus being affected, the couple may decide to terminate the pregnancy.