Pink or blue? Thanks to a new development in genetic testing, women can now begin preparing a “gender-appropriate” nest for their little girl or boy months earlier than the traditional twenty-week sonogram allows. The results of a study published in the
Journal of American Medical Association report that a controversial cell-free fetal DNA blood test can give 95% accuracy in predicting gender as early as seven week into pregnancy.
How does it work? By analyzing the mother’s blood and the fetal DNA carried within it, doctors can look for the male-specific DNA, Y-chromosome. The accuracy of this test improves the closer the woman is to the twenty week gestation mark when tested, and reaches near perfect after that point. Prior to seven weeks, however, the results were found unreliable.
"The improved performance with later gestation is likely attributable to the increased concentration of cell-free fetal DNA within maternal blood as the fetus and placenta develop. This would explain the poor performance of the test prior to seven weeks' gestation and the near-perfect performance in the third trimester,” said the authors of the study.
Medical benefits. In addition to the benefit of knowing which color onesie to buy, this test also offers a safer way to test for genetic abnormalities that tend to be hereditary by gender, such as hemophilia, congenital adrenal hyperplasia, and ambiguous genitalia. This test is safer for both mother and baby than more invasive procedures, such as amniocentesis, which involves
risk of miscarriage, preterm labor and delivery, and amniotic fluid embolism. When medical professionals and parents-to-be gain such information earlier in the pregnancy, a necessary treatment plan can be adjusted accordingly.
For example, if a patient is concerned about the invasive procedures used to test for hemophilia, a typically male-inherited disease, this blood test can eliminate the need for risky tests by determining if the male DNA is present. According to Dr. Diana Bianchi of Tufts University School of Medicine who worked on this study, “it could reduce the number of invasive procedures that are being performed for specific genetic conditions.”
The controversy.However, not everyone is thrilled about these advancements in genetic testing. Dr. Biachi herself warns that this type of test “should only be used by families that are at risk for sex-linked diseases.” In addition, the study, which analyzed 57 clinical studies, did not include at-home tests which can raise problems with accuracy and contamination.
Many companies have started marketing this technology directly to curious soon-to-be parents through
tests designed to be taken at-home and shipped to a laboratory for analysis. Some believe that making this test easily accessible will increase gender selection by parents in countries where there is a clear gender preference and, consequently, increase the number of abortions based on gender. One brand of at-home test, Pink or Blue® has a policy to not ship to China or India due to “high incidence of gender selection.”
The authors also mention that this type of testing has already become a part of regular clinical care in some countries in the U.K. and Western Europe, even without studies such as this one to validate its performance. Ultimately, cell-free fetal DNA testing is about more than just deciding on pink or blue. Rather, it’s about giving accurate information for patients and doctors to make informed decision about their health.
