TUESDAY, Aug. 9 (HealthDay News) -- A simple blood test from mom can spot the sex of a fetus as early as seven weeks into a pregnancy, researchers report.
Because it is noninvasive, the test doesn't carry the same risks, such as miscarriage, as other methods for determining gender.
According to the U.S. research team, the test works by scouring free-floating DNA in the mother's blood, looking for "Y" or male chromosomes. If no Y chromosomes are detected, the fetus is presumed to be a girl.
Although the test does predict "boy" or "girl" with great accuracy, it was not created for this purpose but to detect certain medical conditions instead, the team note.
Still, "there is no reason why it couldn't be [used to determine fetal gender] - the technology is widely available and the test does not require specialized software or the like," said Dr. Diana W. Bianchi, senior author of a paper appearing in the Aug. 10 issue of the Journal of the American Medical Association.
But, she stressed that the screen was developed to spot certain sex-linked medical conditions early in gestation. "The major implications of this study are for three different groups of conditions, two of which are genetic conditions," Bianchi said.
The first of these would be X-linked or sex-linked conditions such as hemophilia, which usually affects boys.
If a woman knows, either because she has a brother or previous child with hemophilia, that she is at risk for having a baby with hemophilia, she would normally undergo invasive genetic testing, Bianchi explained.
That would mean either amniocentesis -- drawing amniotic fluid directly out of the womb -- or chorionic villus sampling, which involves taking tissue directly out of the placenta. Both carry a "small but real" risk of miscarriage, said Bianchi, who is executive director of the Mother Infant Research Institute at
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