In 2007, Dennis Lo and his colleagues used digital polymerase chain reaction or PCR to detect trisomy 21 in maternal blood, validating the method as a means to detect fetal chromosomal aneuploidies, or an abnormal number of chromosomes in a cell. The team conducted their research at the Chinese University of Hong Kong in Hong Kong, Hong Kong, and at the Boston University in Boston, Massachusetts. Because small amounts of fetal DNA appear in maternal blood during pregnancy, Lo and his team hypothesized that they could detect fetal chromosomal aneuploidy trisomy 21, or Down’s syndrome, in a sample of maternal blood. The group diagnosed Down’s syndrome in unborn fetuses by first taking a maternal blood sample, then amplifying the small amounts of fetal DNA in the maternal blood using digital PCR, and applying two genetic methods to that sample. Lo and his colleagues’ experiment demonstrated the accuracy of a novel, noninvasive method for fetal chromosomal aneuploidy testing that can enable people to make informed decisions about their pregnancies.