New Blood Test Reveals Fetus’s Gender Five Weeks after Conception

A new blood test may safely reveal the gender of a fetus in the first trimester, according to new research published in the Journal of the Federation of American Societies for Experimental Biology.

Researchers from KwanDong University College of Medicine, Seoul, Korea, collected maternal plasma samples from 203 women who were between 5 weeks and 12 weeks gestation. Using quantitative methylation-specific polymerase chain reaction of the unmethylated-PDE9A gene, the researchers confirmed the presence of circulating fetal DNA. The researchers used polymerase chain reactions to simultaneously quantify the amount of DYS-14, the Y-chromosome-specific sequence, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in maternal plasma. Phenotypes were confirmed at birth.

The researchers found that the false-negative rate at equivalent specificity was 9.1% for the DYS14 quantification cycle, 7.1% for DYS14 concentration, and 0.0% for the concentration ratio of DYS14/GAPDH, respectively. In women who were carrying males, they found that DYS14, U-PDE9A, and GAPDH concentrations were significantly lower in the false-negative case than in correct case. The researchers also noted significantly positive associations between DYS14, U-PDE9A, and GAPDH concentrations.

“The ratio of DYS14/GAPDH in maternal plasma was an effective biomarker for noninvasive fetal sex detection during the first trimester, indicating that it could be useful for clinical application,” the authors concluded.

The clinical implications for such a test are significant. With the desire to know the gender as early as in a pregnancy as possible, this new test will help clinicians address patients’ questions more quickly and safely than invasive procedures such as such as chorionic villus sampling or amniocentesis, which cannot be performed before 11 weeks gestation. A blood test would also be available to new parents before conclusive information would be available via ultrasound.

“Although more work must be done before such a test is widely available, this paper does show it is possible to predict the sex of a child as early as the first few weeks after conception,” Dr. Gerald Weissmann, editor-in-chief of the journal and professor emeritus of medicine and research professor in the department of medicine at New York University, said in a statement to the press. “At present, parents are sometimes given the wrong information about the sex of their unborn child; this test should prove helpful in resolving any uncertainties of today’s ultrasound observations.”