Using just a few drops of the mother's blood, Acu-Gen Biolab of Lowell, Mass., said the kit could detect the gender of the fetus with 99.9 percent accuracy — and as early as five weeks into pregnancy. The test costs $275 and comes with a 200 percent money-back guarantee.

But now parents are raising concerns about the test — recently 40 people who purchased the kit filed a class-action lawsuit in Massachusetts claiming incorrect test results. In the suit, the claimants said they relied on the company's promise to refund the fee if their tests weren't accurate, but when they tried to get their money back, the company refused to provide a refund and instead changed the terms of the refund policy, acccording to the lawsuit.

According to the lawsuit, at the time that the products were purchased, a customer had to do two things in order to get a refund: wait until the baby was born and provide a valid copy of the child's birth certificate.

However, when the women whose tests turned out to be incorrect tried to get their 200 percent refund, Acu-Gen changed the rules, the parents say. Instead, the company insisted that the women had to deliver a live baby, provide an original birth certificate, provide a blood sample and fingerprints from their baby and more. In some cases, customers were told that they were not entitled to a refund because they were carrying a "vanishing twin," according to the law firm representing the case.

Acu-Gen's kit claims to detect both male-fetus- and female-fetus-specific chromosomal DNA in the expectant mother's blood sample "with an unprecedented sensitivity and specificity."

However, the company does not provide any research or specific studies.