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Blood test to tell baby's gender found reliable
August 9th, 2011
04:00 PM ET

Blood test to tell baby's gender found reliable

A blood test designed to tell the sex of an unborn baby is very reliable, especially after seven weeks' gestation, compared with urine-based tests that are also available to parents, according to new research in this week's issue of Journal of the American Medical Association.

The test based on cell-free fetal DNA taken from the mother's blood, was found to correctly detect a male fetus 95% of the time, when performed seven to 20 weeks’ gestation and then had a near-perfect rate of determining the sex of the child after that.

The blood test was designed to be an alternative to invasive procedures, such as amniocentesis, which involves removing a sample of  amniotic fluid surrounding the fetus, and chorionic biopsies, which test tissue that makes up most of the placenta. These tests detect  inherited birth problems like hemophilia, as well as single -gene disorders such as congenital adrenal hyperplasia and ambiguous genitalia (where a child could have a mix of both sex organs).
"These methods are gold standards for determining fetal abnormality issues, " says Dr. Diana Bianchi, co-author of the paper and executive director of the Mother Infant Research Institute as well as a professor of Pediatrics, Obstetrics  and Gynecology at Tufts University School of Medicine."But some of these procedures are invasive and can carry a small risk of miscarriage. The blood test has no major safety issues."

Authors of the paper looked at 146 studies and pieces of literature published on the effectiveness of the noninvasive prenatal test, and found it to be very accurate, especially as the gestational age of the child became greater.

One of the main concerns to researchers was the easy availability of these tests on the Internet, for non-medical purposes. Companies now tout the test as a quick way for parents-to-be to kill their curiosity and find out the sex of their child as early as five to seven weeks' gestation.

"There are companies that say these tests can help determine the age of the child as early as five weeks,” said Dr. Bianchi, "We just didn't see that, but after seven weeks, the percentage of accuracy in determining a male was much higher and after 20 weeks, it shot up to more than 99 percent."

Because of the ease of the blood test, and the earlier window for sex determination, some medical ethicists feel the test makes it easier for parents to abort a child because of its sex. But scientists and policy experts say even though sex selection may have been documented sporadically in other parts of the world, there is no strong evidence of that happening in the U.S.

"There isn't really data on reasons people choose abortions," notes Susannah Baruch, a lawyer and policy consultant for "Generation Ahead," a U.S. organization that fights for policies that lead to more just and ethical uses of human genetic technologies. "There have been only a few small studies in Asian immigrant populations looking at birth rate ratios which show some skewing towards more boys in second and third born children. But none of it sheds much light on the way first semester screening would be used."

The blood tests are usually given to women who either have a relative or they themselves know they carry a genetic defect that could be transferred to their babies. In some cases, these defects or conditions can be reversed inside the womb, so doctors say the sooner parents know about their unborn baby's issues, the better. Although there is ultrasound technology, such as a sonography that can be performed as early as 11 weeks’ gestation to determine fetal sex, many parents may want to know sooner.
And study authors say, that's the reason they did the research, to make sure parents had reliable and accurate options.

"The availability of reliable noninvasive alternatives to determine fetal sex would reduce unintended fetal losses," noted the authors, "And would presumably be welcomed by pregnant women carrying fetuses at risk for disorders.”


soundoff (26 Responses)
  1. CHD

    Man Man Man. We do not need this test to be invented.

    August 9, 2011 at 22:18 | Report abuse | Reply
    • Juli

      Yes, because finding a safer way to determine if an unborn child has a life threatening illness is just horrible. Do you have any idea the stress a high risk expectant mother has to go through in deciding weather or not to do those more invasive tests. On one hand, it could help her child lead a normal healthy life, on the other, the test itself could kill her child. Don't you think she deserves every medical advancement that could help that process?

      August 10, 2011 at 14:21 | Report abuse |
    • CHD

      @ Juli. This test is not going to make much difference in health care delivery and benefits to patients or expectant mothers. Do you really know Juli that what is the consequences of this test in Islamic, Chinese and South Asian country where they kill baby girl either through abortion? Please reconsider your thought. Thanks.

      August 10, 2011 at 21:04 | Report abuse |
  2. Faith

    A boy or girl... can't people be happy and content with what they get? So many girls were killed the Chinese men won't be able to marry anymore.

    August 10, 2011 at 01:22 | Report abuse | Reply
    • dx2718

      It is perfectly possible to be happy with either but still want to know one way or another ahead of time. You may want to, say, choose a name, paint the nursery, or buy clothes before the baby comes, and knowing whether it's a little girl or little boy will help with that.

      August 10, 2011 at 02:00 | Report abuse |
    • gender roles

      Dx, it is horrifying that gender roles are still rammed down the throats of everyone in our society, starting before birth. Baby girls do NOT need to sleep in a room painted pink or boys in a room painted blue. Newborns CAN wear white, yellow, green, purple, black, etc clothing. If a stranger on the street tells you how cute your baby is and asks, boy or girl? The act of asking the question should NOT mortify you! Nobody should know instantly the gender of a tiny, swaddled baby. Does it matter? Is it important? Will they ask to inspect your child's genitals? Who cares! Let your baby be who they are. It's a BABY, not a "boy" or a "girl". Nobody should be primarily defined by their gender.

      August 10, 2011 at 12:56 | Report abuse |
  3. nikhil india

    this test will encourage female feticide in asia.

    August 10, 2011 at 06:58 | Report abuse | Reply
    • cosmicsnoop

      Something tells me the average 3rd world person in Asia, who would be most likely to kill their girl child, would not be able to afford this test.

      August 10, 2011 at 07:17 | Report abuse |
    • Faith

      They kill the baby girls even right after delivery. The pagan barbarism.

      August 10, 2011 at 11:48 | Report abuse |
    • Michelle

      I love how you throw around the term "Pagan" as if it were slanderous. The pagans I know are generally feminists and would never discriminate by gender. That's much more of a Judeo-Christian thing.

      August 10, 2011 at 12:51 | Report abuse |
    • Bazoing

      The third world middle class is not poor and has been demonstrated to practice female infanticide at a similar rate to that of the poor. Not all poor people are evil; its about the same across classes.

      This test is a terrible thing contrived to make someone rich.

      August 10, 2011 at 23:31 | Report abuse |
    • Faith

      Michelle, I'm from pagan countries and pagans never knew valuing babies or women. Only the Christian missionaries taught us the God-given freedom and equality; it is exclusively Judeo-Christian. The whole West would have been as barbaric as any other civilization if it did not have the Bible. Feminists massacre babies – that's what's women's right to abortion is for.

      August 11, 2011 at 10:09 | Report abuse |
  4. Becky Revalee

    Please, please tell me what genetic/heridatary syndrome can be corrected in utero?? Hemophilia?? Cystic Fibrosis? I dont think so. Lets get the facts straight please before releasing them to the public!!!

    August 10, 2011 at 11:56 | Report abuse | Reply
    • tests

      If only it was stupidity. We need a test and treatment for that and I think that is hereditary.

      August 10, 2011 at 12:59 | Report abuse |
    • cope

      I don't think this test has should be available for all to use especially since it could be used by some barbarically. However, I disagree with you, in the future we may be able to correct genetics in utero and when that happens a blood test such as this would be extremely useful. And I think that day is closer than you think.

      August 10, 2011 at 13:10 | Report abuse |
  5. jon

    Someone needs to explain to me why knowing the gender of your baby within about a month and a half of conception is important in any way. So you can get a head start on choosing a name? Because it these days it really does take more than six months to build a new baby room in a household? Because if it's not the gender you wanted you could get a head start on the adoption and/or abortion process?

    August 10, 2011 at 12:30 | Report abuse | Reply
    • tests

      I am very against gender testing at any stage of pregnancy but I have noticed almost all expectant mothers want to know the gender of their child asap. This is because gender is so very important in society and because most people behave like children and if they get a chance to peek at their presents before birthday/Christmas, they most certainly will do it. Actual birth used to be a time of happiness and wonder as a new baby was born that nobody knew was going to be like. Now, it's a medical procedure just to be gotten out of the way because people already know everything about their baby.

      FYI, all babies need the same things in a nursery regardless of gender. There are no boy vs girl cribs or changing tables. It's all the same. Gender-specific nurserys are only for the parents since newborns can't even see past their own nose. Get over it people and accept whatever you get and be happy about it. Go to the delivery room with two names picked out, if necessary. Would that kill you to have two names ready? AAAhhhhhhhhh, the uncertainty!

      August 10, 2011 at 13:06 | Report abuse |
  6. me

    I am 5 weeks pregnant. and I wanted to buy a couple things for the baby. but even the very, very few non gender specific things, were still pretty gender specific. I mean, they had yellow clothes, with like flowers all over it. I couldn't find anything totally neutral. Is it a requirement? no. it's not necessary. But it's still kinda fun. I didn't find out with my first and we survived.

    August 10, 2011 at 13:22 | Report abuse | Reply
  7. Guest

    I am 12 weeks and would love to already know the gender of my baby! On another note, if you're really that concerned about genetic problems, there are already tests out tehre that can be done BEFORE the baby is ever implanted...and they can tell you the gender. If you have a genetic mutation that will affect only boys, you can choose to only implant girls. Obviously a blood test is less invasive but at that point the baby is already growing and has a heartbeat at 7 weeks.

    August 10, 2011 at 14:10 | Report abuse | Reply
  8. 5thavebabe

    Easier to get rid of female foetuses..I am looking at you Indian retards.

    August 10, 2011 at 15:54 | Report abuse | Reply
    • David Davidson

      Agreed. All this test will do is make it easier for people in India, Pakistan, and other East Asian countries to kill their females. Humanity deserves every ounce of misery it receives.

      August 10, 2011 at 23:49 | Report abuse |
  9. Guest

    This is not a pretty path we are going down. As genetic testing gets easier it will get easier to abort babies with perceived flaws. One the one hand, as a strong proponent of abortion rights, I think this trend is positive because it will kill off the last vestiges of opposition to abortion because most folks will want to get early testing so they can abort babies with serious birth defects. On the other hand, it won't stop with serious birth defects – it will spread to all birth defects and then we have widespread eugenics.

    August 10, 2011 at 18:49 | Report abuse | Reply
  10. Determine Your Baby's Gender

    Predetermining your baby's gender can be a very enjoyable experience. Imagine having the baby of your dreams. There are many programs and systems that claim to give you the success you are looking for. Do

    December 23, 2011 at 21:23 | Report abuse | Reply
  11. Aloisq Banalesx

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    July 17, 2012 at 14:31 | Report abuse | Reply
  12. valersh

    Baby gender determination before birth and conception.
    Baby gender determination by photo of parents only.
    To do this in Facebook I have an account and a group.
    The group is called Baby gender by parents photo.

    December 30, 2013 at 04:10 | Report abuse | Reply
  13. valersh

    Gender determination Baby gender by parents photo. http://www.facebook.com/groups/babygender/

    January 2, 2014 at 10:15 | Report abuse | Reply

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Get a behind-the-scenes look at the latest stories from CNN Chief Medical Correspondent, Dr. Sanjay Gupta, Senior Medical Correspondent Elizabeth Cohen and the CNN Medical Unit producers. They'll share news and views on health and medical trends - info that will help you take better care of yourself and the people you love.