To Know Or Not To Know? New Blood Test Can Tell Fetus’s Sex At Just 7 Weeks

By admin
August 17, 2011

Newly expectant parents can now start picking out colors for the new baby room earlier than previously thought possible, thanks to a new, surprisingly accurate blood test that can determine the sex of a fetus only seven weeks into pregnancy.

According to the August 10th issue of the Journal of the American Medical Association, a review of previous research showed non-invasive DNA tests were able to accurately determine sex at least 95% of the time, while providing an alternative to more invasive, risk-prone tests such as chorionic villus sampling and amniocentesis, for determining the gender of a fetus and related heritable disorders.

Using fetal DNA from the mother's blood to determine the unborn baby's sex is highly effective, between 95% and 98%. According to researcher and reproductive geneticist Diana W. Bianchi, MD, "After seven weeks of gestation, the accuracy of fetal sex detection is very good using maternal blood. After 20 weeks, it was nearly perfect."

The blood test works by scanning the blood of the mother-to-be for fetal DNA, looking for fragments of the male (Y) chromosome to determine if the fetus is a boy. If the chromosome is not present, the fetus is a girl.

The test informs new parents of the baby's gender considerably earlier than standard procedures like ultrasound, which can identify fetal sex at approximately 20 weeks gestation.  Beyond determining gender, the new test is important in helping identify at-risk babies at an early stage of pregnancy, which is critical among families with a history of gender associated diseases, like ambiguous genitalia, X-linked conditions, and single-gene disorders such as congenital adrenal hyperplasia.

While the test could conceivably help parents who are worried about gender-related diseases, some doctors and medical experts fear it could also allow people to delve into the morally murky waters of sex selection.

Toby Schonfeld, a bioethicist at Emory University School of Medicine, explains, “To the extent that getting this information early can make the decision about terminating less traumatic, physically and emotionally, it's generally a good thing. But is it a reasonable social value to say, Look, I've got a boy, and I want a girl? I don't know.”

Given these uncertainties, blood tests that detect gender are not currently widely available in the U.S., have not yet been approved by the Clinical Laboratory Improvement Amendments (CLIA), and are not currently reimbursed by insurers, although they have been been offered for purchase over the Internet for several years.

To ensure that the tests are not used for gender-selection, they're not sold in China or India, where female fetuses are selectively aborted. And at least one company that sells the tests in the United States makes parents sign a waiver saying they are not using it for that purpose.

In the meantime, the tests’ effectiveness means curious parents who don’t want to wait to start handing out those, "It's a Girl" or "It's a Boy" cigars, can now do so earlier than ever before.

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