The Yomiuri ShimbunEleven medical facilities across the nation will soon start a clinical study that will examine all chromosomes of a fetus, in a move that could have implications for Japan’s current prenatal testing system that checks only three chromosomes for abnormalities. The study, which will involve non-invasive prenatal testing (NIPT), could start as soon as February. It will be conducted on about 2,000 pregnant women whose unborn babies are suspected of having chromosomal conditions, and verify the accuracy of these tests. Humans typically have 23 pairs of chromosomes for a total of 46 chromosomes. Testing for chromosomal conditions other than the three permitted is not accurate enough.