Scientists have raised the possibility of a single non-invasive genetic screening for pregnancy disorders after they successfully sequenced the genome of a baby in utero without affecting the amniotic sac.

Labs have been exploring the pregnant woman’s blood plasma for some time because it contains cell-free DNA from her developing foetus. Further exploration of this phenomenon could lead to a non-invasive maternal blood tests to look at a foetus’ genetic make-up.

University of Washington researchers have now developed a method that uses a maternal blood sample at 18 weeks gestation, and a paternal saliva specimen to map the foetus’ DNA.

Using the technique they were able to pick out the baby’s genetic material inherited from each parent with over 98 per cent accuracy. Additionally, they can assess more subtle variations in the foetus’ genome, down to one-letter changes in the DNA code.

Jacob Kitzman, a National Science Foundation Graduate research Fellow said: “The improved resolution is like going from being able to see that two books are stuck together to being able to notice one word misspelled on a page.”

Matthew Snyder, who led the research alongside Mr Kitzman, said that they checked the accuracy of the tests using the umbilical cord blood collected at birth. He stressed that although the results were impressive, there is still work to be done to improve the technique.

Dr Jay Shendure from the University of Washington said: “This work opens up the possibility that we will be able to scan the whole genome of the foetus for more than 3,000 single-gene disorders through a single, non-invasive test.

“The capacity of genomics to generate data is outstripping our ability to interpret it in ways that are useful to physicians and patients. Although the non-invasive prediction of a foetal genome is now technically feasible, its interpretation – even for single-gene Mendelian disorders – will remain an enormous challenge.”