Pregnant women can now know the sex of their baby as early as seven weeks into a pregnancy with a simple blood test. This new technology allows expectant mothers to know whether they are having a boy or girl months earlier than usual, according to a study in today's Journal of the American Medical Association.

The researchers found that tests that look for fragments of the baby's DNA in a sample of the mother's blood are about 95% to 99% accurate, depending on several factors, according to LA Times. The genetic tests used to determine whether a fetus is male or female are surprisingly accurate and noninvasive.

The tests were accurate when there was enough cell-free fetal DNA in the mother's blood - this can be as early as seven weeks into her pregnancy, according to researchers. The best results were found after 20 weeks of gestation. Blood tests before seven weeks and any tests using urine were not reliable, the study found. 

With the results of these tests being so dependable and accurate, more families could use them to check the gender of their child early in the mother's pregnancy or to look for sex-chromosome-based genetic conditions.

Although the new blood tests could help families at high risk of having a baby with rare genetic diseases, some experts worry that this could lead to an ethical dilemma: some couples could misuse the blood tests in order to abort a fetus based on gender.

Arthur Caplan, director of the Center for Bioethics at the University of Pennsylvania, says that female fetuses are commonly aborted in India. A May analysis in The Lancet estimates that 4.2 million and 12.1 million female fetuses were "selectively" aborted in India from 1980 to 2010., a practice that is noticeably skewing the ratio of boys and girls in that country.

It all comes down to the purpose of the tests - whether it is for those who wish to prevent the risk of gender-linked diseases, those who are merely curious and people considering the more ethically controversial step of selecting the sex of their children.