Although the tests aren't regulated by the Food and Drug Administration, Goldberg predicts this may change, as the tests become more popular.
Female fetuses are commonly aborted in India, he says. A boy is a boy is probably a boy. Here's the general idea: A mother's blood carries free-floating fragments of her child's DNA during the time that she carries the fetus. Blood tests before seven weeks and any tests using urine were not reliable, the study found.
European doctors routinely use the tests.
The study analyzed reams of research on fetal DNA tests, and found that carefully conducted tests could determine sex with accuracy ranging from 95 percent at seven weeks to 99 percent at 20 weeks.
A potential worry is that women might abort fetuses of an undesired sex.