Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started
My Medicine

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Health & Pregnancy

Font Size

Boy or Girl? Fetal DNA Tests Often Spot On

Report Confirms Effectiveness of Using Mother's Blood to Detect Unborn Baby’s Gender, Paves Way for Alternatives to Invasive Tests
WebMD Health News
Reviewed by Laura J. Martin, MD

Aug. 9, 2011 -- Using fetal DNA from a mother's blood to determine the unborn baby's sex is highly effective, according to a new review of the research.

"After seven weeks of gestation, the accuracy of fetal sex detection is very good using maternal blood," says researcher Diana W. Bianchi, MD, a reproductive geneticist and executive director of the Mother-Infant Research Institute at Tufts Medical Center in Boston.

At seven weeks, she found 95% accuracy. "After 20 weeks, it was nearly perfect."

The research involves tests done by hospital or research groups worldwide. "It shouldn't be confused with what the direct-to-consumer companies are advertising [to help parents find out the gender of their unborn infants]," she says.

The hope, Bianchi says, is to use these research-based tests to detect unborn babies at risk for sex-linked disorders, such as hemophilia, and other genetic disorders early in the pregnancy. Depending on those results, it could delay or rule out the need for more invasive tests such as amniocentesis.

The review is published in the Journal of the American Medical Association.

Fetal DNA Tests: Evaluating the Research

Bianchi and her colleagues evaluated 57 published studies. They pooled the data and results from these studies. In all, the research represented 3,524 pregnancies bearing boys and 3,017 pregnancies bearing girls.

The studies looked at tests of fetal DNA in maternal blood and urine. For about a decade, experts have known that maternal blood contains fetal DNA.

Overall, the tests using blood detected the Y chromosome indicating a boy 95.4% of the time. The studies that evaluated DNA in maternal urine were unreliable, the researchers say.

As the pregnancy went on, the blood test became more reliable. That is believed to be due to the increased concentration of fetal DNA within the mother's blood, Bianchi says.

By 20 weeks, the test was 99% accurate, she says.

The test is not routinely done by doctors in the U.S., Bianchi says. That's partly due to the lack of reimbursement by insurers, she says. The research she reviewed came from hospitals and research groups worldwide.

1 | 2 | 3

Pregnancy Week-By-Week Newsletter

Delivered right to your inbox, get pictures and facts on
what to expect each week of your pregnancy.

Today on WebMD

hand circling date on calendar
Track your most fertile days.
woman looking at ultrasound
Week-by-week pregnancy guide.
Pretty pregnant woman timing contaction pains
The signs to watch out for.
pregnant woman in hospital
Are there ways to do it naturally?
slideshow fetal development
pregnancy first trimester warning signs
What Causes Bipolar
Woman trying on dress in store
pregnant woman
Woman looking at pregnancy test
calendar and baby buggy
dark chocolate squares