July 5, 2005 -- A controversial new blood test, which is being marketed to pregnant women, indicates the sex of a fetus five weeks into a pregnancy.
While the test allows parents to pick the colors for the nursery and baby clothes well in advance, it also has a darker potential: allowing women to get an early abortion if they don't want a baby of a particular sex.
Paul and Tonya Hunter of Middletown, Wis., have three active little boys and Tonya is now 16 weeks pregnant with their fourth child. They are anxious to find out whether they are having another boy or their first girl.
"The suspense is killing me," Tonya said, "and we won't be able to tell accurately from an ultrasound for at least another month. And even then they say it's not always effective or accurate. So when I found out about this ..."
Hunter is referring to the new test, called the Baby Gender Mentor. A woman need only prick the tip of her finger and send the blood sample to a Massachusetts laboratory, where a computer analyzes the blood for traces of fetal DNA and indicates its gender.
"I think we are hoping for a girl, and we would love to have the experiences that go along with a girl," said Paul.
"We're having a baby either way," Tonya said. "But it would be fun to know when decorating rooms and switching kids rooms around."
The gender test costs $275, and it is advertised as being 99 percent accurate. Pregnancystore.com, an online maternity store, says it has sold more than 1,000 kits in three weeks.
Because the test is considered so accurate, so simple to use, and can be done so early in a pregnancy, some people worry it will make it all too easy for women to choose whether to have a boy or a girl.
"My concern is that this will be used to further abortions purely for the purpose of one sex or another, independent of any genetic problems or medical problems," said Dr. Michael Grodin of the Boston University School of Public Health and clinical medical ethicist for the Boston Medical Center.
"There's no proof people are using it for gender selection," said Sherry Bonelli, chief executive officer of Pregnancystore.com. "That's not the intended purpose of the kit, and we really don't see women using it for that purpose."
Grodin remains concerned, however. "It's a disingenuous statement to say there's 'no proof'," he said. "And what we do know from surveys is that people will use it for gender selection."
The Hunters -- who say they "just want to know" -- got the test results in less than 48 hours. They logged onto the company's Web site to learn they are having another boy.
"It's kind of overwhelming. This is our fourth boy," Paul said.
"We have a lot of testosterone in this house," said Tonya.
Now they have time to prepare for even more.
ABC News' John McKenzie filed this report for "World News Tonight."