91色情片

A more accurate method of combining the results from maternal blood tests and
ultrasound screening for Down鈥檚 syndrome could reduce the need for invasive
tests. A study by the Wolfson Institute of Preventative Medicine in London
showed that it could increase the success rate of existing tests from 70 to 85
per cent and reduce the number of false positives from 5 to 1 per cent (The
New England Journal of Medicine, vol 341, p 461). The new method works by
integrating the results of the maternal blood samples and ultrasound scans done
in the first and second trimesters.