Fetal Sex Test Can Reveal Gender at 7 Weeks
Is it a boy or a girl? Parents anticipating the sex of their baby no longer have to wait 20 weeks into pregnancy. According to a study published in Wednesday’s Journal of the American Medical Association, a simple blood test can reveal whether you are having a girl or boy as early as seven weeks.
The new technology works by isolating fetal DNA, or “cell-free DNA,” from the fetus, which floats in the mother’s blood.
The blood tests detect gender after seven weeks of gestation and are superior to using an ultrasound to rule out genetic abnormalities. The tests are 95 percent accurate and can correctly identify a male fetus 95.4 percent of the time and a female fetus 98.6 percent of the time, says the study.
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Researchers found that ultrasound and urine tests are often unreliable in determining fetal gender early in development. Even amniocentesis, a process involving a needle to remove and test amniotic fluid, can cause the mother to miscarry and cannot be performed until 15 weeks, or after the first trimester.
“It could reduce the number of invasive procedures that are being performed for specific genetic conditions,” said Dr. Diana Bianchi of Tufts University School of Medicine, who worked on the new study.
The blood test can help mothers who harbor the sex-linked genetic disorder hemophilia, avoid invasive tests by knowing the fetus is female.
“If you know in the first trimester that there’s no male DNA, that the fetus is female, then an invasive procedure isn’t needed,” said Bianchi.
Nonetheless, women carrying a male fetus still need to undergo a definitive test, such as an amniocentesis, to find out whether the fetus is affected.
Bianchi analyzed 57 peer-reviewed studies on gender testing that revealed blood tests, commonly used in Europe but not in U.S., can detect a fetus’ sex a week or two after a woman misses her menstrual cycle. This varies greatly from the standard 18 to 20 weeks period when physicians can perform an ultrasound to determine the gender.
The blood tests used in European countries have decreased the number of women having invasive tests, said Bianchi.
U.S. hospitals generally do not offer the tests because they require sophisticated labs to avoid contaminating blood samples, says James Goldberg of the California Pacific Medical Center in San Francisco. Additionally, the U.S. Food & Drug Administration does not regulate the blood tests, although increased popularity could eventually change this, says Goldberg.
Families at risk of having a baby with genetic disorders will benefit from the new technology. However, some experts are concerned that certain couples will use the blood tests for gender selection and abortion.
The study’s authors warned that marketers who sell the blood tests should inquire about a couple’s plans to use the results.
Recent research showed that an increasing number of women in India who already have daughters are using prenatal tests and having abortions upon learning the fetus is female.
Similar research on U.S. abortion trends is lacking, so experts are not sure whether gender selection plays a large role, or any role, in the number of abortions performed annually, said Susannah Baruch, a policy consultant for the Generations Ahead, an advocacy group that studies genetic techniques and gender issues.
Consumer Genetics Inc. sells an early gender blood test called “Pink or Blue”. The product is available online for $25 plus $265 or more for laboratory testing.
The company claims the test is 95 percent accurate. Annually, Consumer Genetics sells more than 1,000 kits, said Terry Carmichael, the company’s executive vice president.
However, the company will not sell the kits to customers in China and India due to the likelihood that customers are purchasing the test for gender selection. Consumer Genetics will not test blood samples unless women sign a consent form agreeing they will not use the results for gender selection, says Carmichael.
