Great Ormond Street Hospital in the capital is to trial a new test for Downs' Syndrome to see if it should be offered to pregnant women by the NHS.
Non-invasive prenatal testing (NIPT) can predict with 99% accuracy whether a baby has Down's but is currently only available in private hospitals.
The blood test detects a baby's genetic material and does not carry any risk of miscarriage like current invasive tests.
At present, testing for Down's involves a combination of an ultrasound scan of the baby and a blood test for the mother.
Experts then estimate a woman's chance of having a baby with Down's.
Those found to be at higher risk can opt for further tests, such as amniocentesis -but this carries a one in 100 risk of miscarriage.
The new test also screens for the rare genetic conditions Edward's syndrome and Patau syndrome.
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