A controversial blood test allows expectant parents to determine their baby's gender as early as seven weeks.
The test, which looks for pieces of male chromosomes in the blood, according to Reuters, is widely used in Europe but is not yet allowed in the United States.
New research in the Journal of the American Medical Association says the test is 95% accurate when taken seven weeks into pregnancy, while 99% accurate at 20 weeks, The New York Times reports. A urine test, however, was only accurate 41% of the time-- "worse than flipping a coin," study research Diana Bianchi told LiveScience.
Supporters say the test can help families at risk for gender-linked diseases avoid invasive and more costly genetic testing further down the road. For one, Duchenne muscular dystrophy only affects boys, so the test for that disease would be unnecesary if the baby is found to be female.
Over-the-counter blood tests guaranteeing results as early as five weeks into pregnancy have been avaliable for a few years, but their accuracy is unclear, the Times reports.
But others worry the popularity of an early gender indicator raises ethical concerns sex-biased abortions.
For example, evidence suggests China's one child per couple policy and preference for male heirs has contributed to abortions and a large gender imbalance. The study's authors suggest that couples who buy the test should be questioned about how they plan to use the results, according to The Associated Press.
"I would have a lot of difficulties offering such a test just for general identification. Gender is not an abnormality," Dr. Lee Shulman, chief of clinical genetics at Northwestern Memorial Hospital in Chicago, told The Associated Press.