In a meta-analysis appearing online this week in the Journal of the American Medical Association, Johns Hopkins University's Stephanie Devaney and her colleagues review the "overall test performance of noninvasive fetal sex determination using cell-free fetal DNA." In analyzing 80 data sets from 57 studies, the team found that, "despite interstudy variability, [test] performance was high using maternal blood." Devaney et al. found that while test performance increased with gestational age — such that "sensitivity and specificity for detection of Y chromosome sequences was greatest using RT-qPCR after 20 weeks' gestation," they write — 94.8 percent sensitivity and 98.9 percent specificity were achievable at just seven to 12 weeks. Brigham and Women's Hospital's Louise Wilkins-Haug, who was not involved in the research, tells The New York Times that this study "has wide-reaching implications." Study co-author Diana Bianchi tells the Times that an "important aspect of the study is how this advances prenatal care." Bianchi adds that she's now studying consumers' motivations to purchase prenatal genetic sex determination services — which can run up to $250 or more, are not currently reimbursed by health insurers — because she says it's "very important to educate health care providers that pregnant women are buying these tests."
Sex Determination at Seven Weeks
Aug 10, 2011