Scientists have developed a maternal blood test capable of detecting thousands of serious genetic conditions in a developing foetus.
This potentially reduces the need for invasive diagnostic procedures during pregnancy.
The technique, known as non-invasive foetal sequencing (NIFS), analyses tiny fragments of foetal DNA that circulate in the mother's bloodstream.
Researchers say it could offer a safer alternative to procedures such as amniocentesis and chorionic villus sampling (CVS), which carry a small risk of miscarriage.
The findings are due to be presented at the European Society for Human Genetics conference in Gothenburg.
According to Dr Christopher Whelan of the Broad Institute of MIT and Harvard, the test can identify a wide range of serious genetic conditions, including many covered by major newborn screening and foetal anomaly panels.
Conditions detected during the validation study included Noonan syndrome, CHARGE syndrome, Stickler syndrome, achondroplasia, and several other rare genetic disorders.
Researchers tested the method on 565 pregnancies at an average gestational age of 17 weeks. By sequencing DNA fragments and applying advanced computational analysis, they examined nearly 23,000 genes in each foetus.
When compared with results obtained through amniocentesis or CVS, the new test identified 95 to 99 per cent of genetic variants detected by invasive methods and more than 97 per cent of clinically relevant variants.
Non-invasive prenatal blood tests are already used to screen for conditions such as Down syndrome. Researchers say the new approach could significantly expand the range of detectable disorders.
Whelan said the test could be particularly useful when ultrasound scans or other screenings suggest a possible abnormality, as many expectant mothers decline invasive testing because of the associated risks, stress, cost, or limited access.
Experts welcomed the development but urged caution.
Widespread screening could identify genetic variations of uncertain significance, potentially causing anxiety for parents and leading to unnecessary medical interventions.