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Blood Test Proves Reliable to Determine Fetal Sex

A simple over‐the‐counter blood test that can determine the sex of your baby as early as seven weeks gestation has been available in Europe and elsewhere for some time. This test is useful for parents Blood Testconcerned about gender‐linked diseases, as well as for those curious about the sex of their fetus. American doctors have not prescribed these tests because they are unregulated and the labs producing them are not federally certified to do so. The reliability these tests has not been clearly established until now. A new study carried out by the National Institutes of Health (NIH) has analyzed research on fetal DNA tests — 57 studies involving about 6,500 pregnancies — and found that carefully conducted tests could determine sex with accuracy of 95 percent at 7 weeks to 99 percent at 20 weeks. Testing of urine samples and of blood samples before 7 weeks gestation have been proven unreliable, however.


Most DNA tests on the market use blood to determine the sex of the fetus and cost $250 or more. To do the test, women prick their fingers and send blood samples to the lab by mail. If the Y chromosome is detected, the fetus is very likely male. Absence of a Y chromosome would probably mean the fetus is female, but could mean that fetal DNA was not found in that blood sample which is common before 7 weeks.


This test could be helpful as a noninvasive alternative to amniocentesis for determining sex and sex‐ related problems, such as ambiguous genitalia, X‐linked conditions, and single‐gene disorders, such as congenital adrenal hyperplasia. These disorders are not common in the general population, however. Researchers and medical ethicists fear the test will be used primarily by the public as a method of gender selection, leading to the elective termination of female fetuses in the first trimester by parents hoping for a male child. In some countries like India and China, the cultural preference for boys is well‐ documented, and more boys than girls are born in ratios that are strongly suggesting prenatal sex selection is occurring. Many people find it ethically easier to justify the termination of an early pregnancy than an advanced one. As a result, this technology is igniting a heated ethical debate before it is even clinically available. Should this blood test be made widely available in the U.S. in the future, professional guidelines will need to be developed.

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